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Susitna Valley Area
Alaska
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599
.A4
S87
1973
UNITED STATES DEPARTMENT OF AGRICULTURE
Soil Conservation Service
In cooperation with
UNIVERSITY OF ALASKA INSTITUTE OF AGRICULTURAL SCIENCES
Issued December 1973
Major fieldwork for this soil survey was done in the period 1961-68. Soil names and
descriptions were approved in 1968. Unless otherwise indicated, statements in. the
publication refer to conditions in the Area in 1968. This survey was made cooperatively
by the Soil Conservation Service and the University of Alaska Institute of Agricultural
Sciences. It is part of the technical assistance furnished to the Montana Soil Conservation
Subdistrict of Alaska and the Wasilla Soil Conservation Subdistrict of Alaska.
Either enlarged or reduced copies of the soil map in this publication can be made
by commercial photographers, or they can be purchased on individual order from t~e
Cartographic Division, Soil Conservation Service, United States Department of Agri-
culture, Washington, D.C. 20250.
HOW TO USE THIS SOIL SURVEY
T HIS SOII, SURVEY contains infor-
mation that can be applied in man-
aging farms, ranches, and woodlands; in
selecting sites for roads, ponds, buildings,
and other structures; and in judging the
suitability of tracts of land for agricul-
ture, industry, and recreation.
Locating Soils
All the soils of the Susitna Valley Area
are shown on the d etailed map at the back
of this publication. This map consists of
many sheets made from aerial photo-
gra phs. Each sheet is numbered to cor-
r espond with a number on the Index to
Ma p Sheets.
On each sheet of the detailed map, soil
areas are outlined and are identified by
symbols. A ll areas marked with the same
symbol a r e the same kind of soil. The soil
symbol is inside the area if there is enough
room; otherwise, it is outside and a pointer
shows where the symbol belongs.
Finding and Using Information
The "Guide to Mapping Units" can be
used, to find information. This guide lists
all the soils of the Area in alphabetic
order by map sy mbol and gives the man-
agement group of each. It also shows the
page where each soil is described and the
page for the mana~ement group in which
the soil has been pJ aced.
Individual colored maps showing the
rela ti ve suitability or d egr ee of limitation
of soils for many specific purposes can be
developed by using the sail map and the
inf ormation in the text. Tra nslucent mate-
rial can be used as an overlay o\·er the soil
map and colored to show soils that have
the same limitation or suitability. For
example, soils that have a slight limitation
for a given use can be colored green, those
with a moderate limitation can be colored
yellow, and those with a severe limitation
can be colored red.
Fa1'7M1'S and thmJe who wo'l'!c with farm-
e1'S can learn about use and management of
the soils from the soil descriptions and
from the discussion of the management
groups.
Foresters and ot he1•s can refer to the sec-
tion "W ood,land," where the soils of the
Area are grouped according to their suit-
ability for trees.
Ga;me managers, sportsmen, a;nd others
can find information about soils and wild-
life in the section "Wildlife."
Oowmuni ty planners and others can
r ead about soil properties that affect the
choice of sites for nonindustrial buildings
and for recreation areas in the section
"Recreation."
Enrtineers and builders can find, under
"Engmeering Uses of the Soils," tables
that contain test data, estimates of soil
properties, and information about soil
features that affect engineerin~ practices.
S cientists atnd others can reaa. about how
the soils formed and how they are classified
in the secti on "Formation and Classifica-
tion of S oils."
N ewcome1•s in t he Susitn a Valley Area
will be especially interested in the section
"General Soil Map," where broad patterns
of soils are described. They will also be
interested in the information about the
Area g iven at the beginning of t h e publi-
cation and in the section "General Nature
of the Area" at the end of this survey.
U.S . GO VERNME NT PRI NTIN G OPFI C!1 1113
For sa le by the Superintenden t or.DoTT¥lJU .:~~ernmont Printing Office
WosblDg~:IQ# ~
Alaska Resources
Library & Information Service~
Anchorage. AK
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How this survey was made ___________ _
General soil map ____________________ _
1. Rabideux-Salamatof association __
2. Nancy-Kashwitna association ___ _
3. N ancy-Delyndia association ____ _
4. Kashwitna-Homestead associa-tion _______________________ _
5. Susitna-Schrock association _____ _
6. Clunie-Tidal Marsh association __
7. Salamatof-Jacobsen association __
Descri~tions ~f the soils _____________ _
Bermce senes _____ ---------______ _
Caswell series ____________________ _
Chena series ______________________ _
Chulitna series ___________________ _
Clunie series _____________________ _
Coal Creek series _________________ _
Delyndia series ___________________ _
Dinglishna series __________________ _
Flat Horn series __________________ _
Gravelly alluvial land _____________ _
Gravel pits ______________________ _
Homestead series _________________ _
Jacobsen series ___ -----------------Kalifonsky series _________________ _
Kasbwitna series _________________ _
Killey series __ -----------------_____ _ Lucile series ______________________ _
Mixed alluvial land ________________ _
Moose River series ________________ _
Nancy series ______________________ _
Niklason series ___________________ _
Rabideux series ___________________ _
Salamatof series ___________________ _
Schrock series _____________________ _
Slikok series ______________________ _
Contents
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Descriptions of the soils-Continued Susitna series ____________________ _
Terrace escarpments ______________ _
Tidal flats ____ -------____________ _
Tidal marsh ______________________ _
Wasilla series _____________________ _
Whitsol series _____________________ _
Use and management of the soils _____ _
Crops and pasture ________________ _
Land clearing ____ ---------------
Fertilizer requirements __________ _
Suitable crops __________________ _
Estimated yields ________________ _
Capability grouping _____________ _
Management groups ____________ _ Woodland _______________________ _
Woodland groups _______________ _ Wildllie _________________________ _
Recreation _______________________ _
Engineering uses of the soils ________ _
Engineering classification systems __
Engineering test data ____________ _
Engineering properties of the soils __
Engineering interpretations of the soils _________________________ _
Formation and classification of soils ___ _
Factors of soil formation ___________ _
Classification of soils ______________ _
General nature of the area ___________ _
Physiography and drainage _________ _ Geology _________________________ _
Climate __________________________ _
Vegetation _______________________ _
History, settlement, and industry ___ _
Literature cited _____________________ _
Glossary ___________________________ _
Guide to mapping units ____ Following
Issue!I December 1973
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sF1
SOIL SURVEY OF SUSITNA VALLEY AREA, ALASKA /913
BY DALE B. SCHOEPHORSTER AND ROBERT B. HINTON 1
UNITED STATES DEPARTMENT OF AGRICULTURE, SOIL CONSERVATION SERVICE, IN COOPERATION WITH UNIVER·
SITY OF ALASKA INSTITUTE OF AGRICULTURAL SCIENCES
THE SUSITNA VALLEY ARE.A. occupies about
730,390 acres, of which 28,890 acres are lakes and
streams, excluding the Susitna River. This Area is in the
Cook Inlet-Susitna Lowland of south-central Alaska
(fig. 1).
The Susitna Area is about 85 miles in length from north
to south and ranges from 8 to 18 miles m width. It is
almost parallel to the lower course of the Susitna River
and extends from a point about 10 miles north of Tal-
keetna southward to the tidal waters of Cook Inlet. The
northern half of the Area includes strips of land on both
sides of the Susitna River and makes up most of the
Montana Soil Conservation Subdistrict. The southern half,
which includes ~the western pa:vt of the Wasilla Soil Con-
servation Subdistrict, is bounded on the west by the Susitna
River and on the east by the adjoining Matanuska Valley
Soil Survey Area.
Most of the Area is sparsely populated, and large tracts
/'
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Figure I.-Location of Susitna Valley Area in Alaska.
are uninhabited. According to the U.S. Census, the village
of Talkeetna, the largest community, had a population of
76 in 1960. Most of the rural settlement is concentrated
along the Alaska Railroad and along a new major high-
way that almost parallels the Susitna River in the north-
ern half of the Area. Cabins near many of the lakes and
streams are used mainly for recreation.
How This Survey Was Made
Soil scientists made this survey to learn what kinds of
soil are in the Susitna Valley Area, where they are located,
and how they can be used. The soil scientists went into
the Area knowing they likely would find many soils they
had already seen and perhaps some they had not. They
observed the steepness, length, and shape of slopes, the
size and speed of streams, the kinds of native plants or
crops, the kinds of rock, and many facts about the soils.
They dug many holes to expose soil profiles. A profile is
the sequence of natural layers, or horizons, in a soil; it
extends from the surface down into the parent material
that has not been changed much by leaching or by the
action of plant roots.
The soil scientists made comparisons among the profiles
they studied, and they compared these profiles with those
in areas nearby and in places more distant. They classified
and named the soils according to nationwide uniform pro-
cedures. The soil series and the soil phase are the categories
of soil classification most used in a local survey.
Soils that have profiles almost alike make up a soil
series. Except for different texture in the surface layer,
all the soils of one series have major horizons that are
similar in thickness, arrangement, and other important
characteristics. Each soil series is named for a town or
other geographic feature near the place where a soil of
that series was first observed and mapped. Nancy and
Rabideux, for example, are the names of two soil series.
All the soils in the United States having the same series
name are essentially alike in those characteristics that
affect their behavior in the undisturbed landscape.
Soils of one series can differ in texture of the surface
soil and in slope, stoniness, or some other characteristic
1 Assisting with the fieldwork were CHARLES D. BowEN, WILLIAM E. CRANE, JR., JAcK D. CRouT, EuGENE P. DAVIS, RoBERT E;
Fox, CHARLES L. GmDNER, JR., EDWARD C. HERREN, CoLIN A. HoGAN, GALEN E. KINTNER, CHARLES H. MAINE, LEONARD A. NEUBAUER,
JoHN H. NEWTON, RoBERTS. PoLLocK, WILLIAM B. PARKER, CHARLES M. PowERS, RoDNEY E. PREATOR, WILLIAM I. SMITH, OLLIE G.
SPROusE, JR., DELBERT D. THOMAS, JoHN G. ToLBERT, J. C. TRuE, AuGUST J. TURNER, JACK C. WILLIAMs, CARL D •. WILSON, JR., ~and
RoBERT C. WINGARD, JR.
ARLIS
Alasl<.a Resources Library & Information Services
Library Building, Suite 111
3211 Providence Drive
Anchorage, AK 99508-4614
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2 SOIL SURVEY
that affects use of the soils by man. On the basis of such
differences, a soil series is divided into phases. The name of
a soil phase indicates a feature that affects management.
For example, Nancy silt loam, undulating, is one of sev-
eral phases within theN ancy series.
After a guide for classifying and naming the soils had
been worked out, the soil scientists drew the boundaries
of the individual soils on aerial photographs. These photo-
graphs show woodlands, buildings, field borders, trees, and
other details that help in drawing boundaries accurately.
The soil map in the back of this publication was prepared
from the aerial photographs.
The areas shown on a. soil map are called mapping units.
On most maps detailed enough to be useful in planning
the management of farms and fields, a mapping unit is
nearly equivalent to a soil phase. It is not exactly equiva-
lent, because it is not practical to show on such a map
all the small, scattered bits of soil of some other kind that
have been seen within an area that is dominantly of a
recognized soil phase.
Some mapping units are made up of soils of different
series, or of different phases within one series. Two such
kinds of mapping units are shown on the soil map of the
Susitna Valley Area: soil complexes and undifferentiated
groups.
A soil complex consists of areas of two or more soils,
so intermingled or so small in size that they cannot be
shown separately on the soil map. Each area of a complex
contains some of each of the two or more dominant soils,
and the pattern and relative proportions are about the
same in all areas. The name of a soil complex consists of
the names of the dominant soils, joined by a hyphen.
Dinglishna-Moose River complex is an example.
An undifferentiated group is made up of two or more
soils that could be delineated individually but are shown
as one unit because, for the purpose of the soil survey,
there is little value in separating them. The pattern and
proportion of soils are not uniform. An area shown on
the map may be made up of only one of the dominant
soils, or of two or more. The name of an undifferentiated
group consists of the names of the dominant soils, joined
by "and." Susitna and Niklasonfine sandy loams, overflow,
is an example.
In most areas surveyed there are places where the soil
material is so rocky, so shallow, or so severely eroded that
it cannot be classified by soil series. These places are shown
on the soil map and are described in the survey, but they
are called land types and are given descriptive names.
Gravelly alluvial land is a land type in the Susitna
Valley Area.
While a soil survey is in progress, samples of soils are
taken, as needed, for laboratory measurements and for
engineering tests. Laboratory data from the same kinds
of soil in other places ·are assembled. Data on yields of
crops under defined practices are assembled from farm
records and from field or plot experiments on the same
kinds of soil. Yields under defined management are esti-
. mated for all the soils.
But only part of a soil survey is done when the soils
have been named, described, and delineated on the map,
and the laboratory data ·and yield data have been as-
sembled. The mass of detailed information then needs to
be organized in such ·a way as to be readily useful to dif-
ferent groups of users, among them farmers, managers of
woodland, and engineers.
On the basis of yield and practice tables and other data,
the soil scientists set up trial groups. They test these
groups by further study and by consultation with farmers,
•agronomists, engineers, and others, then adjust the groups
according to the results of their studies and consultation.
Thus, the groups that are finally evolved reflect up-to-date
knowledge of the soils and their behavior under present
methods of use and management.
General Soil Map
The general soil map at the back of this survey shows,
in color, the soil associations in the Susitna Valley Area.
A soil association is a landscape that has a distinctive pro-
portional pattern of soils. It normally consists of one or
more major soils and at 1east one minor soil, and it is named
for the major soils. The soils in one association may occur
in another, but in a different pattern.
A map showing soil associations is useful to people who
want a general idea of the soils in an area, who want to
compare different parts of an area, or who want to know
the location of large tracts that are suitable for a certain
kind of land use. Such ·a map is a useful general guide in
managing a watershed, a wooded tract, or a wildlife area,
or in planning engineering works, recreational facilities,
and community developments. It is not a suitable map for
planning the management of a farm or field, or for select-
ing the exact location of a road, building, or similiar struc-
ture, because the soils in any one association ordinarily
differ in slope, depth, stoniness, drainage, and other
characteristics that affect their management.
The soil associations in the Susitna Valley Area are
discussed in the following pages. The terms for texture
used in the title for several of the associations apply to
the surface layer. For ex·ample, in the title for association
1, the words silt loams refer to texture of the surface layer.
1. Rabideux-S\alamatof Association
Dominantly nearly level to steep, well-drained silt loams
that are shallow and moderately deep over sand or gravelly
sand and are on uplands/ and nearly level, very poorly
drained, fibrous peats in muskegs
This association is in two large areas in the northern
part of the survey ·area. It consists of nearly level and
undulating soils on terraces and of nearly level and rolling
to steep soils on moraines and in muskegs. The vegetfttion
is mainly paper birch and white spruce, but in the muskegs
it is sphagnum moss, sedges, low shrubs, and a few black
spruce. Elevation ranges from 250 to 1,300 feet.
This association occupies about 25 percent of the survey
area. Rabideux soils make up about 50 percent of the
association, Salamatof soils ·about 20 percent, and minor
soils about 30 percent.
Rabideux soils are on terraces and · moraines. They
formed in 15 to 30 inches of silt loam underlain by very
gravelly sand or fine sand. These soils are well drained and
are very strongly acid and strongly acid .
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SUSITNA VALLEY AREA, .A!LASKA 3
Salamatof soils are in muskegs, where drainage is very
poor and the water table is seasonally high. These soils
were derived chiefly from sphagnum moss and are ex-
tremely acid.
Among the minor soils are Chulitna and Nancy soils on
terraces and Moose River, Killey, and Kalifonsky soils
in depressions and on bottom lands along streams.
Most of the acreage in this association is wooded and is
used mainly as wildlife habitat. A few paper birch, how-
ever, are harvested for logs and fuel. Also, homesteaders
along the roads have cleared a few areas of Rabideux,
Chulitna, and Nancy soils for crops. The principal crops
are perennial grasses, barley, oats, potatoes, and hardy
vegetables. Areas near many of the lakes and streams are
used for recreational buildings and for campsites. In addi-
tion, sand and gravel can be obtained from the substratum
of the well-drained soils.
2. Nancy-Kashwitna Association
Dominantly nearly level to steep, well-drained silt loams
that are moderately deep and shallow over sand or
gravelly sand j on uplands
This association is in the central part of the survey area.
It consists of nearly level and undulating soils on terraces
and of rolling to steep soils on moraines. The vegetation is
mainly paper birch and white spruce. Elevation ranges
from 150 to 800 feet.
This association makes up about 20 percent of the sur-
vey area. Nancy soils make up about 30 percent of the asso-
ciation, Kashwitna soils about 20 percent, and other less
extensive soils about 50 percent.
Nancy soils are on terraces and on moraines. These soils
formed in 15 to 30 inches of silt loam underlain by very
gravelly sand. Kashwitna soils are mainly on terraces.
They formed in silt loam 10 to 18 inches thick over gravelly
sand. Both of these soils are well drained, and they are
strongly acid to very strongly acid. ·
Salamatof soils make up 10 percent of the acreage of the
minor soils in this association, and Whitsol, Flat Horn,
Lucile, Caswell, and Moose River soils make up the re-
maining 40 percent. Salamatof soils are in depressional
areas in muskegs. They are nearly level and are very
poorly drained.
Most of this association is wooded and is used as wild-
life habitat, but a few tracts have been cleared and are
used as cropland. The principal crops are perennial
grasses, barley, oats, potatoes, and hardy vegetables. Many
areas near the lakes and streams are used for recreational
buildings and for campsites. In addition, road fill, sand,
and gravel are obtained from many ar:eas of the Kash-
witna and Nancy soils. ·
3. Nancy-Delyndia Association
Dominantly nearly level to steep, well-drained and some-
what excessively drained silt loams that are moderately
deep and shallow over sand or gravelly sand j on uplands
This association is in the southern part of the survey
area on broad terraces. Most of the acreage is nearly level
and undulating, but a few areas are rolling to moderately
steep. These soils are well drained and somewhat exces-
sively drained. The vegetation is dominantly paper birch,
white spruce, and quaking aspen. Elevation ranges from
25 to 30 feet.
This association makes up about 12 percent of the sur-
vey area. Nancy soils make up about 25 percent of the asso-
ciation, Delyndia soils about 20 percent, and other less
extensive soils about 55 percent.
Nancy soils are well drained. They formed in 15 to 30
inches of silt loam underlain by fine sand. Delyndia soils
are somewhat excessively drained. They formed in sandy
material that had a capping of silt loam 7 to 12 inches
thick. Both of these soils are strongly acid to very strongly
acid.
Salamatof soils make up about 15 percent of the acreage
of the minor soils in this association, and Flat Horn,
Moose River, Caswell, and Jacobsen soils make up the
remaining 40 percent. Salamatof soils are nearly level and
very poorly drained and are in muskegs.
Most of this association is wooded. The areas are used
mainly as wildlife habitat, though a few trees are har-
vested for fuel and for logs. In addition, homesteaders
near Flat Horn Lake and the settlement of Susitna have
cleared a few areas for growing garden vegetables.
4. Kashwitna-Homestead Association
Dominantly nearly level to steep, well-drained silt loams
that are shallow and very shallow over gravelly sand or
gravelly sandy loamj on uplands
This association is in the southern part of the survey
area along its eastern boundary. Some of the soils in this
association are nearly level and are on broad outwash
plains south of the Susitna River. Others are rolling to
steep and are on moraines north of the river. The soils
in this association are well drained and moderately well
drained. The vegetation is dominantly paper birch, white
spruce, and quaking aspen. Elevation ranges from 100 to
600 feet.
This association makes up about 5 percent of the survey
area. Kashwitna soils make up about 35 percent of the
association, Homestead soils about 15 percent, and other
less extensive soils about 50 percent.
Kashwitna soils are nearly level and undulating and
are on outwash plains. They formed in 10 to 18 inches
of silt loam underlain by very gravelly sand. These soils
are well drained and are strongly acid to very strongly
acid.
Homestead soils are dominantly rolling to steep, but a
few areas are nearly level. They formed in 5 to 10 inches
of silt loam underlain by gravelly material. They are
strongly acid to very strongly acid.
Less extensive soils in this association are in the Jacob-
sen, Lucile, Nancy, and Salamatof series. The Jacobsen
and Salamatof soils are nearly level and poorly drained
and occupy most of the muskegs scattered throughout the
association.
Most of this association is wooded. The areas are used
mostly as wildlife habitat, but a few trees are harvested
for logs and fuel. Also, a few areas along the lakes and
streams are used for recreational purposes.
r
4 SOIL SURVEY
5. Susitna-Schrock Association
Dominantly nearly level, well-drained, stratified fine
sandy loams and silt loams that are deep over sand or
gravelly sand/ on allwvial plains
This association is in the northern part of the survey
area. It consists of nearly level soils on alluvial plains.
Some of these soils are along the major streams of the
Area, and others are on large islands near the Susitna
River. Many of the areas are dissected by secondary stream
channels and oxbow sloughs. The vegetation is mainly
cottonwood, paper birch, and white spruce. Elevation
ranges from 10 to 500 feet.
This association makes up about 10 percent of the sur-
vey area. Susitna soils make up a:bout 50 percent of the
association, Schrock soils about 10 percent, and less exten-
sive soils about 40 percent.
Susitna soils occupy slightly lower positions closer to
the rivers and streams than Schrock soils. Both formed in'
stratified silty and sandy water-laid sediment, about 40
to 60 inches thick, underlain by very gravelly material.
Both are well drained and strongly acid. Susitna soils gen.;
erally have a dark-gray surface layer, 'and Schrock soils
have a dark-brown surface layer.
Among the less extensive soils are Niklason soils near
Susitna soils; Moose River and Wasilla soils in depres-
sions; and Gravelly alluvial land in frequently flooded
areas next to the nvers and streams.
Most of the acreage in this association is wooded and is
used mainly as wildlife habitat. A few cottonwoods, white
spruce, and paper birch are harvested for logs and fuel.
In addition, homesteaders have cleared a few areas along
the roads for use as cropland. The principal crops . are
barley, bromegrass, potatoes, oats and peas for silage, and
hardy vegetables.
6. Clunie-Tidal Marsh Association
Dominantly nearly level, very poorly drained, fibrous
peats and poorly drained, clayey sediment/ on tidal pla:Yns
This associ~tion is in the southerrn_nost part of the survey
area. It consists of nearly level, shghtly acid to neutral
soils in depressions on broad tidal plains that border Cook
Inlet. Qn the P.oorly drained soils in this association, the
vegetation consis~ of sedges, grasses, and other plants that
com;nonly .gr?w 1.?-coastal mea~ows. On the very poorly
~ram~d soils m slightly depressiOnal areas, the vegetation
IS mamly moss, sedges, <and low shrubs. Elevation ranges
from a few feet above the average level of high tides to
25 feet.
This ass?ciation makes up about 4 percent of the survey
area. Olume peats make up about 35 percent of the associ-
ation, Tidal marsh about 30 percent, and less extensive soils
about 35 percent.
Olunie soils are in large muskegs, generally between
areas of Tidal marsh and uplands. They consist of very
poorly drained, brownish, fibrous peat, a:bout 30 to 40
inches thick, underlain by clayey sediment.
Tidal marsh is on broad coastal areas slightly above the
level of high tides. It consists of blue to greenish-gray,
poorly drained, clayey tidal sediment that is occasionally
flooded.
Among the less extensive soils are small tracts of Tidal
flats, which are next to tidal waters and are almost bare
of vegetation.
Most of this association is used as wildlife habitat, espe-
ci,ally for migratory waterfowl.
7.. Salamatof-Jacobsen Association
Domilnantly nearly level, very poorly drained, fibrous peats
in muskegs/ and nearly level, very poorly drained, very
stony silt loams along the edges of muskegs
This association is in many parts of the survey area. It
consists of nearly level, very poorly drained and poorly
drained soils in broad irregular areas. The vegetation is
dominantly sphagnum moss, sedges, and low shrubs, but
black spruce grows in a few areas. Elevation ranges from
25 to 500 feet.
This association makes up about 24 percent of the survey
area. Salmatof soils make up ·about 75 percent of the asso-
ciation, Jacobsen soils about 10 percent, and minor soils
about 15 percent.
Salamatof soils are in muskegs. These soils are very
poorly drained. They consist of deep, coarse peats derived
mainly from sphagnum moss. Jacobsen soils are near the
outside edges of muskegs ·and in tracts along small streams.
These soils are poorly drained. They consist of dark
grayish-brown, very stony silt loam that is overlain by a
thick mat of moss and decomposing organic material. Both
soils are strongly acid to extremely acid and have a season-
ally high water table.
The minor soils consist of well drained and moderately
well drained soils on islands within muskegs and in areas
next to muskegs.
The soils in this association are used mainly as wildlife
habitat.
Descriptions of the Soils
This section provides detailed information about the
soils in the Susitna Valley Area. It describes each soil
series, and then each soil, or mapping unit. The soils are
described in alphabetical order.
The description of a soil series mentions features that
apply to all of the soils of that series. Differences among
the soils of one series are pointed out in the descriptions
of the individual soils or are apparent in the name.
A representative profile of each series is described in
detail in the first mapping unit. This profile is for use by
scientists, engineers, and others who need to make highly
technical soil interpretations. The lavers, or horizons, are
designated by symbols such as A1, ·B21, and 01. These
symbols have special meaning for soil scientists. Many
readers, however, need only remember that symbols be-
ginning with "A" are for surface soil; those with "B" are
for subsoil; and those with "0" are for substratum, or
parent material.
The color of each horizon is described in words, such as
yellowish brown, and is also indicated by symbols for hue,
value, and chroma, such as 10YR 3/2. These symbo~s,
which are called Munsell color notations, are used by soil
scientists to evaluate the color of the soil precisely (930)2 •
2 Italic numbers in parentheses refer to Literature Cited, p. 69.
SUSITNA VALLEY AREA, AL.AJSKA 5
Unless otherwise stated, the color terms in the survey are
for moist soils.
The texture of the soil refers to the content of sand, silt,
and clay. It is determined by the way the soil feels when
rubbed between the fingers, and it is checked by laboratory
analyses. Each mapping unit is identified by a textural
class name, such as "fine sandy loam." This name refers
to the texture of the surface layer or A horizon.
The structure is indicated by the way the individual soil
particles are arranged in larger grains or aggregates, and
the amount of pore space between grains. The structure of
the soil is described by terms that denote strength or grade,
size, and shape of the aggregates. For example, a l·ayer
may consist of soil materials that have weak, fine, blocky
structure.
Boundaries between the horizons are described so as to
indicate their thickness and shape. The terms for thickness
are abrupt, clear, gradual, and diffuse. The shape of the
boundary is described as smoot'h, wavy, irregular, or
broken.
Other terms used for describing the soils are defined in
the Glossary. For more general information about the soils,
the reader can refer to the section "General Soil Map," in
which the broad patterns of soils are described. The ap-
proximate ·acreage and proportionate extent of the soils
are given in table 1, and their location and extent are
shown on the detailed soil map at the back of this survey.
Following the name of each mapping unit is a symbol in
parentheses. This symbol identifies the soil or land type on
the detailed map at the back of this survey. Shown at the
end of each description of each mapping unit are the man-
agement group and the capability classification in which
the mapping unit has been placed. The page on which each
management group is described is listed in the "Guide to
Mapping Units." The locations of the soils in the Area are
shown on the detailed map at the back of this survey, and
the acreage and proportionate extent of the mapping units
are shown in table 1.
TABLE 1.-Approwimate acreage and proportionate ewtent of the soils
Soil
Bernice sandy loam, steep __________________ _
Caswell silt loam __________________________ _
Chena fine sandy loam _____________________ _
Chulitna silt loam, nearly leveL _____________ _
Chulitna silt loam, undulating _______________ _
Chulitna silt loam, rolling __________________ _
Clunie peat _______ -----_______ --------____ _
Coal Creek silt loam _______________________ _
Delyndia silt loam, nearly level_ _____________ _
Delyndia silt loam, undulating ______________ _
Delyndia silt loam, rolling __________________ _
Delyndia silt loam, hilly---------------------Delyndia-Salamatof complex _____________ -__ _
Dinglishna sandy loam _____________________ _
Dinglishna-Moose River complex ____________ _
Flat Horn silt loam, nearly leveL ____________ _
Flat Horn silt loam, undulating _____________ _
Gravelly alluvial land. ____ -------__ --------_ Gravel pits _______________________________ _
Homestead silt loam, nearly level. ___________ _
Homestead silt loam, undulating ____________ _
Homestead silt loam, rolling _________________ _
Homestead silt loam, hilly ___ -----------------
Homestead silt loam, moderately steep _______ _
Jacobsen very stony silt loam _______________ _
Kalifonsky silt loam _______________________ _
Kashwitna silt loam, nearly leveL------------Kashwitna silt loam, undulating _____________ _
Kashwitna silt loam, rolling _________________ _
Kashwitna silt loam, hilly_------------------Kashwitna silt loam, moderately steep _______ _
Kashwitna silt loam, steep __________________ _
Killey-Moose River complex ________________ _
Lucile silt loam ___________________________ _
Mixed alluvial land ________________________ _
Moose River silt loam _____________________ _
Nancy silt loam, nearly leveL _______________ _
Nancy silt loam, undulating ________________ _
Nancy silt loam, rolling ____________________ _
Nancy silt loam, hilly-----------------------Nancy silt loam, moderately steep ___________ _
Nancy silt loam, steep _____________________ _
Nancy silt loam, sandy substratum, nearly
llivel------------------------------------
1 Less than 0.05 percent.
Acres Percent
6, 790
11,270
460
3,990
6, 350
680
10, 280
1,420
9,960
7, 020
1, 320
370
1, 160
1, 680
3,340
14, 150
3,890
3,400
100
1,990
1, 610
500
750
670
13,830
4,850
23, 140
7,690
2, 760
3,270
1,450
90
15, 620
11, 140
2, 160
20, 720
11, 100
6,470
4, 100
6,960
6, 940
260
16, 630
0. 9
1.5
. 1
. 5
. 9
. 1
1.4
• 2
1.4
1.0
.2
(1)
• 2
. 2
. 5
2. 0
. 5
. 5
(1)
• 3
.2
. 1
. 1
. 1
2. 0
. 7
3. 1
1.1
.4
. 5
. 2
(1)
2. 1
1.5
. 3
2. 8
1.6
. 9
.6
1.0
1.0
(1)
2. 3
Soil Acres Percent
Nancy silt loam, sandy substratum, undulating __ 3,830 • 5
Nancy silt loam, sandy substratum, rolling _____ 1,490 .2
Nancy silt loam, sandy substratum, hilly __ -____ 1, 920 • 3
Nancy silt loam, sandy substratum, moderately
steeP-----------------------------------250 (1) Niklason fine sandy loam ____________________ 4, 700 . 6 Rabideux silt loam, nearly leveL _____________ 25,360 3. 5 Rabideux silt loam, undulating _______________ 27,400 3. 8 Rabideux silt loam, rolling ___________________ 10,380 1.4 Rabideux silt loam, hilly ____________________ 8,330 1.1
Rabideux silt loam, moderately steep _________ 13,910 2. 0 Rabideux silt loam, steep ____________________ 5,280 • 7
Rabideux silt loam, shallow, nearly leveL _____ 4,760 . 7
Rabideux silt loam, shallow, undulating _______ 5,790 . 8
Rabideux silt loam, shallow, rolling ___________ 360 (1)
Rabideux silt loam, shallow, hilly_ .. __________ 230 (1)
Rabideux silt loam, shallow, moderately steep __ 1, 230 • 2
Rabideux silt loam, sandy substratum, nearly
level------------------------------------770 • 1
Rabideux silt loam, sandy substratum, undu-laijng ___________________________________ 830 • 1
Rabideux silt loam, sandy substratum, rolling __ 220 (1)
Rabideux silt loam, sandy substratum, hilly ___
Rabideux silt loam, sandy substratum, moder-
200 (1)
ately steep ______ ----------____ -----______ 60 (1)
Salamatof peat. _____________ ------____ -----244, 090 33.4 Schrock silt loam, nearly leveL _______________ 7,590 1.0 Slikok mucky silt loam. _____________________ 3,900 • 5 Susitna fine sandy loam _____________________ 39, 110 5. 3
Susitna and Niklason fine sandy loams, over-flow ____________________________________ 6, 150 . 8
Terrace escarpments ________________ --------700 . 1 Tidal fiats _________________________________ 5, 610 . 8 Tidallllarsh _______________________________ 8, 120 1.1 Wasilla silt loam ___________________________ 2, 670 .4 Whitsol silt loam, nearly level ________________ -7, 700 1.0 Whitsol silt loam, undulating _________________ 3, 330 • 5 Whitsol silt loam, rolling ____________________ 2, 080 . 3 Whitsol silt loam, hilly ______________________ 760 . 1
Whitsol silt loam, moderately steep ___________ 60 (1)
Lakes and streams (excluding Susitna
Rive~------------------------------28, 890 4. 0
Total _____________________________ 730, 390 100.0
r
6 SOIL SURVEY
Bernice Series
The Bernice series consists of strongly sloping to ste~p,
excessively drained, coarse-text:ure~ soils on ~arrow 0r~
rruce escarpments. The vegetatwn IS paper birch, white
spruce, and quaking aspen. Elevation ranges from 100 to
800 feet. Bernice soils generally are near the edges of large
areas of Nancy, Kashwitna, and Rabideux soil~. .
In a representativ~ profile a mat of decomposmg orgamc
material and fine roots overlies a surbce layer of dark-
gray silt loam about 1 inch thick. The sub~oil, aJbout 4
inches thick, is dark reddish !brown to yellowish brown. It
generally is silt loam or fine sandy loam in the upper part
and sandy loam or gravelly sandy loam below. The under-
• lying material is olive-brown gravelly sandy loam and
olive very gravelly coarse sand.
Most areas of Bernice soils are wooded and are used
mainly a;s wildlife habitat. A few small areas, however,
are a source of gravel 'and road fill.
Bernice sandy loam, steep (12 to 45 percent slopes)
(BeF).-This is the only Bernice soil mapped in the survey
area. It is on narrow escar-pments between terraces of dif-
ferent levels and between terraces and flood 'plains. The
areas generally are between100 and 300 feet in length.
Representative profile (SWY4NW'l4 sec. 32, T. 22 N., R.
4: W.):
01-1lh inches to 0, dark reddish-brown mat of decomposing
organic rna terial ; many roots ; abrupt, wavy boundary.
A2-0 to 1 inch, dark-gray (lOYR 4/1) silt loam; weak, thin,
platy structure; friable; many roots; very strongly
acid; abrupt, wavy boundary.
B21-1 to 1lh inches, dark reddish-<brown ( 5YR 3/3) silt loam ;
weak, fine, granular structure ; friable ; many roots ;
a few small pebbles; very strongly acid; clear, wavy
boundary.
B22---1lh to 3lh inches, brown (7.5YR 4/4) fine sandy loam;
very weak, fine, subangular blocky structure ; very
friable ; common roots ; a few pebbles ; very strongly
acid; clear, wavy boundary.
B3-3lh to 5 inches, yellowish-brown (10YR 5/4) sandy loam;
single grain ; loose ; common roots ; many pebbles and
pockets of coarse sand ; very strongly acid ; clear, wavy
boundary.
01-5 to 9 inches, olive-brown (2.5Y 4/4) gravelly sandy loam;
single grain ; loose ; common roots ; many pockets of
coarse sand; very strongly acid.; clear, wavy boundary.
II02---9 to 30 inches, olive (5Y 4/3) very gravelly coarse sand;
single grain ; loose ; a few roots ; very strongly acid.
The A2 horizon and the B horizon range from sandy loam
to silt loam within a distance of a few feet. The mantle of
silty and sandy material ranges from 4 to 12 inches thick over
the very gravelly material in the 0 horizon. In places the
horizons are discontinuous and distorted because of frost
action and soil creep. A few strata and pockets· of medium-
textured and coarse-textured material are in the 0 horizon.
Permerubility is rapid in this Bernice soil, and available
moisture capacity is low~ Plant roots can penetrate to a
depth of 20 inches. Runoff is mpid, .and the haza·rd of
water erosion is very severe. Fertility is low.
Included with this soil in mrupping are a few small areas
of soils that formed in10 to 15 inches of silt loam underlain
by sand or gravel. Also included are spots of deep sandy
soils.
This soil is used mainly as woodland and ·as wildlife
habitat. A few areas, however, are a good source of gravel
and road fill. Management group 26 (VIIe-2).
Caswell Series
In the Caswell series are nearly level, moderately well
drained soils that formed in roughly stratified sandy .and
silty sediment. These soils are in broa~ shallow depressiOns
along drainageways on ter;rac~s and :I? tracts next to lakes
and muskegs. The vegetatii:>Il; IS dommant~y black spruce,
scattered paper birch, and willow. ElevatiOn ranges from
50 to 500 feet. Caswell soils generally are near well-
drained Delyndia and Nancy soils on terraces.
In a representative profile a fairly thick mat of roots,
moss and decomposing organic matter .overlies a lay~r
of ~ayish silt loam about 11./z inches thick. The ~ubsoil,
about 12 inches thick, is mottled. It generally IS. dark
reddish-brown silt loam in the uppermost 2 or 3 mches
and light olive-brown .san~ and olive loan;.y san~ below.
The underlying matermlis roughly stratified ohve and
light olive-brown silty and sandy sediment over very
gravelly sand at a depth of about 32 inches. . .
Caswell soils are wooded and are used as wildhfe
habitat.
Caswell silt loam (0 to 3 percent slopes) (Ca).-This
is the only Caswell soil mapped in the survey area. It is
in broad depressions and along drainageways, large lakes,
muskegs, and flood plains. ·
Representative profile ( 1,200 feet north and 100 feet east
of the northwest corner of sec. 35, T. 16 N., R. 5 W.) :
01-3 to 1 inC'h, dark reddish-brown (5YR 2/2) mat of coarse
partly decomposed forest litter and moss ; many fine
roots; extremely acid; abrupt, wavy boundary.
02-1 inch to 0, black ( 5YR 2/1) finely divided organic matter;
many fine roots ; mycelia; many charcoal fragments;
extremely acid; abrupt, wavy boundary.
A2-0 to 1lh inches, gray (10YR 5/1) silt loam; common,
medium, prominent mottles of dark brown (7.5YR
3/2) ; weak, thin, platy structure; very friable; com-
mon roots ; a few small pockets of sand ; very strongly
acid; abrupt, irregular boundary.
B21-1lh to 4 inches, dark reddish-brown (5YR 3/3 silt loam;
common, coarse, distinct mottles of dark yellowish
brown (10YR 4/4) ; weak, medium, subangular blocky
structure that breaks to weak, fine, granular; very
friable; common roots; a few, fine, hard concretions;
very strongly acid; clear, wavy boundary.
B22-4 to 9 inches, light olive-brown (2.5Y 5/4) sand; com-
mon, coarse, distinct mottles of dark yellowish brown
(10YR 3/4) ; single grain; loose; about 30 percent
of mass consists of large convoluted pockets or patches
of dark-brown, olive-brown, and grayish-brown silt
loam; massive; very friable; slightly smeary when
rubbed between the fingers; common roots; very
strongly acid; clear. wavy boundary.
B3-9 to 14 inches, olive ( 5Y 4/3) loamy sand; single grain;,
loose; weakly cemented convoluted streaks of dark
brown (5YR 3/3) and brown (7.5YR 4/4) make up
about 40 percent of the horizon ; a few roots ; a few
pebbles; very strongly acid; abrupt, wavy boundary.
01-14 to 20 inches, olive ( 5Y 4/3) very fine sandy loam; com-
mon, medium, prominent mottles of brown (7.5YR
4/4) ; weak, medium, platy structure; a few roots;
strongly acid; clear, smooth boundary.
02-20 to 23 inches, light olive-brown (2.5Y 5/6) sand; com-
mon, medium, distinct mottles of brown (7.5YR 4/4);
single grain ; loose ; a few roots ; strongly acid ; abrupt,
smooth boundary.
03-23 to 32 inches, olive (5Y 5/3) silt loam; common, fine,
prominent mottles of reddish brown ( 5YR 4/4) around
old root channels; moderate, thin, platy structure;
friable; a few roots; a few, thin, roughly horizontal
strata of fine sand; a few rounded pebbles; strongly
acid; clear, smooth boundary.
SUSITNA VALLEY AREA, ALAJSiKA 7
IIC4-32 to 40 inches, olive (5Y 4/3) very gravelly sand; single
grain ; loose ; a few weakly cemented streaks of brown
(7.5YR 4/4) ; ·large compact pockets of iron-coated
gravel; strongly acid.
The roughly stratified silty and sandy sediment range from
30 to 40 inches thick over very gravelly sand. The silty and
sandy strata vary in:number, thickness, and arrangement. In
places a layer of moderately firm silt loam as much as several
inches thick overlies the very gravelly substratum. In places
rounded pebbles and gravel make up as much as 15 percent
of the mass in the lower part of the stratified sediment. The
very gravelly substratum is closely packed and contains many
cobblestones and iron stains.
Permeability and available moisture capacity are mod-
erate in this Caswell soil. Plant roots can penetrate to a
depth of about 30 inches. Runoff is slow. T~e water tab~e
generally is at a depth of more than 30 mches, but 1t
rises to within a few inches of the surface for short
periods.
Included with this soil in mapping are small spots of
poorly drained soils of the Coal Creek, Killey, am"! Moose
River series. Also included are small areas of soils that
are shallow to very gravelly material.
Most of this Caswell soil is wooded and is used as wild-
life habitat. The trees, dominantly black spruce, grow
slowly and have little commercial value. If cleared, areas
of this soil would be suitable for growing oats, barley,
perennial grasses, potatoes, and other hardy vegetables.
Management group 5 (Ilw-1).
Chena Series
In the Chena series are nearly level, excessively drained
soils on alluvial plains along the edges of major streams
of the survey area. These soils formed in a very thin mantle
of silty and. fine sandy sediment laid down by wate:: ov~r
thick deposits of very gravelly sand. The vegetatiOn lS
mainly paper birch, white spruce, cottonwood, willow,
and alder. Elevation ranges from 50 to 400 feet. Chena
soils generally are near Niklason and Susitna soils.
In a representative profile a mat of decomposing organic
matter about 2 inches thick overlies a thin layer of very
dark grayish-brown silt loam. Below is about 10 inches
of dark grayish-brown fine sandy loam and olive-gray
loamy sand. The underlying m3!terial is loose very gravelly
sand that extends to a depth of more than 40 inches.
The acreage of these Chena soils is wooded and is used
as wildlife habitat, as woodland, and for recreational
purposes.
Chena fine sandy loam (0 to 3 percent slopes) (Ch).-
This is the only Chena soil mapped in the survey area. It
occupies a few scattered tracts on or along the edges of
flood plains of the major streams.
Representative profile (about 500 feet south and 500
feet east ofthe northeast corner of sec. 7, T. 23 N., R. 4 W.) :
01-2 inches to 0, very dark brown (10YR 2/2) mat of decom-
posing organic matter; many roots; very strongly
acid; abrupt, wavy boundary.
A1-0 to 1% inches, very dark grayish-brown (10YR 3/2)
silt loam; weak, fine, granular structure; very friable;
many roots; strongly acid; clear, wavy boundary.
01-1% to 6 inches, dark grayish"brown (2.5Y 4/2) fine
sandy loam ; weak, fine, granular structure ; very
friable; common roots; medium acid; clear, wavy
boundary.
02-6 to 11 inches, olive-gray (5Y 4/2) loamy sand; single
grain ; loose; common roots ; medium acid; gradual
boundary.
451-728-·73--2
IIC3-11 to 40 inches, olive-gray (5Y 4/2) very gravelly sand;
single grain; loose; many rounded stones and cob-
blestones ; medium acid.
The mantle of loamy and sandy sediment ranges from about
5 to 12 inches thick over very gravelly sand. The surface layer
ranges from silt loam to very fine sandy loam in texture. In
places rounded stones and cobblestones are on or near the
surface.
Permeability is rapid in this soil, and available moisture
capacity is low. The water table generally is at a depth of
more than 4 feet, but small areas are flooded occasionally
for short periods. Runoff is slow, and the hazard of ero-
sion is slight.
Included with this soil in mapping are patches of Nik-
lason and Susitna soils. Also included are a few small
areas of Mixed alluvial land that are flooded occasionally.
Most of this Chena soil is wooded and is used as wild-
life habitat, but a few areas support stands of cottonwood
and white spruce that are suitable for logging. A few small
areas next to streams and roads are used for such recre-
ational activities as overnight camping, picnicking, and
hiking. In places the hazard of occasional flooding is a
moderate limitation for intensive recreational activities.
If cleared, this soil is well suited to perennial grasses for
hay or pasture. It is too shallow and droughty for good
growth of row crops. Management group 22 (VIs-1).
Chulitna Series
The Chulitna series consists of nearly level and un-
dulating to rolling,.well-drained silt loams. Some of these
soils are on high terraces, and others are on low moraines.
The vegetation is mainly paper birch and white spruce.
Elevation ranges from 300 to 1,000 feet. Generally, these
soils are near soils of the Rabideux series.
In a representative profile a mat of decomposing organic
material and roots overlies a surface layer of gray silt
loam about 1 to 2 inches thick. The subsoil is dark reddish-
brown to olive-brown silt loam to a depth of about 21
inches. The underlying material is olive silt loam to a
depth of rubout 37 inches and loose, coarse, olive-gray very
gravelly sand below.
Most of the acreage of these soils is wooded and is used
mainly as wildlife habitat. In a few places, however, white
spruce and paper birch ·are harvested to provide fuel and
logs for local use (fig. 2). Also, several small areas have
been cleared for use as cropland.
Chulitna silt loam, undulating (3 to 7 percent slopes)
(CIB).-This soil has the profile described as representa-
tive of the series. It is on high terraces and moraines. Slopes
are short.
Representative profile (NW;iSW;i sec. 10, T. 24 N.,
R. 5 W.):
01-3 inches to 0, dark reddish-brown (5YR 2/2) mat of partly
decomposed forest litter; many fine roots; mycelia ;
extremely acid; abrupt, wavy boundary.
A2-0 to 2 inches, gray (10YR 5/1) silt loam; weak, thin,
platy structure ; friable ; many roots ; a few streaks
of very dark grayish brown (10YR 3/2); very
strongly acid; abrupt, irregular boundary.
B21-2 to 4 inches, dark reddish-brown (2.5YR 2/4) silt
loam ; moderate, fine, granular structure; very fri-
able; many roots; many, very fine, hard concretions;
a few weakly cemented fragments in the uppermost
one-half inch; very strongly acid; clear, wavy
boundary.
SO]L SURVEY
Figure 2.-A homesteader's cabin on a Chulitna silt loam.
B22-4 to 9 inches, reddish-brown (5YR 4/4) silt lo am;
streaks and patches of strong brown (7.4YR 5/6)
and dark yellowish brown (10YR 4/4) ; weak, medium,
subangular blocky structure, very friable ; common
roots; very strongly acid; abrupt, wavy boundary .
.A2b-9 to 10¥2 inches, grayish-brown (2.5Y 5/2) silt loam; a
few streaks of very dark gray (10YR 3/1) ; weak, thin,
platy structure; friable; thin discontinuous bands of
very dark gray (10YR 3/1) at surface of horizon ;
common roots; very strongly add; abrupt, wavy
boundary.
B2b-10V:J to 16 inches, dark-brown (7 .5YR 3/4) silt loam;
a few patches of dark yellowish brown (10YR 4/4) ;
a few i solated pockets of material from the .A2b
horizon; weak, fine, subangular blocky structure; fri-
able ; a few roots; strongly acid; clear, wavy boundary.
B3b-16 to 21 inches, olive-brown (2.5Y 4/4) silt loam;
patches of yellowish brown (10YR 5/6) and d a rk
yellowish brown (10YR 4/4) ; a few, fine, distinct
mottles of clark brown (7.5YR 4/4) around old root
channels ; weak, fine, subangular blocky . structure ;
friable; a few roots; strongly acid; gradual boundary.
C1-21 to 37 inches, olive (5Y 4/3) silt loam; massive; friable;
a few p atches of dark grayish brown (2.5Y 4/2) ; a
few, fine pores; a few charcoal fragments ; dis·con-
tinuous lenses of fine sand at base of horizon; a few
roots; strongly acid; clear, smooth boundary.
IIC2-37 to 44 inches, olive-gray (5Y 4/2) very gravelly sand;
single grain; loose; many rounded stones and cobble-
stones ; strongly acid.
The combined thickness of 1fue two sequences ranges from
about 18 to 25 inches. These sequences generally formed entirely
in silt loam, but in places the lower part formed in very fine
sandy loam. The mantle of silt loam ranges from 30 to 40
inches in thickness and is underlain by loose very gravelly
sand or sand. In places in the northwestern part of the survey
area this mantle is underlain by very gravelly glacial till that
is moderately compact.
Permeability is moderate in this soil, and available
moisture capacity is moderate to high. Plant roots can
penetrate to a depth of about 30 inches. Runoff is slow
to medium, and the hazard of water erosion is slight to
modemte.
Included with this soil in mapping are small tracts of
Rabideux soils. Also included are a few poorly drained
spots.
Most of this Chulitna soil is wooded. It is suitable for
growing paper birch and white spruce for commercial uses
and ·also for growing oats, barley, perennial grasses,
potatoes, and hardy vegetables. It is also suitable for use
as wildlife habitat and for intensive recreational areas,
such as picnic grounds, campsites, and pl·aygrounds. Man-
agement group 4 (Ile-2).
Chulitna silt loam, nearly level (0 to 3 percent slopes)
(CIA).-This soil is on high terraces in the southern third
of the survey area.
Permeability and available moisture capacity are mod-
erate in this soil, and runoff is slow. Roots can penetrate
to 'a depth of 30 inches.
Included with this soil in mapping are small areas of
Rabideux soils that are moderately deep over sand or very
gravelly sand. Also included, in the northwestern part of
the survey area, are many spots of somewhat poorly
drained Kalifonsky soils. In addition, several large areas
of a deep, moderately well drained soil north of Talkeetna
are included. Tlus soil contains a few strata of fine sand
and has a firm substratum that contains many rounded
pebbles.
Most of this Chulitna soil is wooded, but a few areas
have been cleared for cultivation. The principal crops are
bromegrass, timothy, oats, barley, potatoes, and hardy
garden vegetables . The wooded areas are suitable for use
as wildlife habitat. The better stands of paper birch and
wlute spruce have some commercial value. Much of the
paper birch is average, however, and the white spruce
trees generally are scattered. Tlus soil is also suitable for
such intensive recreational use as campsites, picnic
grounds, and playgrounds. Management group 2 (Ilc-2).
Chulitna silt loam, rolling (7 to 12 percent slopes)
(CIC).-This soil is on low moraines. Included in mapping
are a few areas of a hilly soil, a few small wet depressions,
and small tracts of Rabideux soils that are moderately
deep over very gravelly material.
Permeability is moderate in this Chulitna soil, and
available moisture capacity is moderate to high. Plant
roots can penetrate to a depth of 30 inches. Runoff is me-
dium, and the hazard of water erosion is moderate.
Most of this Chulitna soil is wooded, but a few areas
have been cleared for cultivation. The principal crops are
bromegrass, oats, barley, potatoes, and hardy vegetables.
Commercial stands of paper birch and white spruce can be
grown on this soil. The vegetation provides suitable habi-
tat for wildlife. Management group 7 (IIIe-2).
Clunie Series
In the Clunie series are near-ly level, very poorly
drained peats that are underlain by moderately fine tex-
tured tidal sediment. These soils are in broad depressions
on tidal plains. The vegetation is mainly sedges, rushes,
mosses, and low-growing shrubs that commonly grow in
muskeg areas. Elevation ranges from 0 to 25 feet. Chmie
soils generally are bordered by large tracts of Tidal marsh.
In a representative profile a Clunie soil consists of very
dark gray to dark-brown, coarse peat to a depth of about
37 inches. Below is gray silty clay loam tidal sediment.
Most of the acreage of these soils is used as wildlife
habitat.
Clunie peat (0 to 3 percent slopes) (Cn).-This is the
only Clunie soil mapped in the survey area. It is in shallow
depressions on tidal plains.
Representative profile (NIV%NW1;.4 sec. 6, T. 14 N .~ R.
6\V.):
SUSITNA VALLEY AREA, ALASKA 9
Oil-0 to 18 inches, very dark gray (10YR 3/1) to grayish-
brown (lOYR 5/2, squeezed dry) mat of live sphag-
num moss and very coarse peat made up of slightly
decomposed moss, sedge leaves, and woody particles;
many roots; contains a few patches of peat that have
thin, grayish silt coatings; medium acid; gradual,
smooth boundary.
Oi2-18 to 37 inches, dark-brown (7.5YR 3/2) to brown (lOYR
4/3, squeezed dry) coarse sedge peat interlayered with
moss peat; a few woody particles; several thin strata
of grayish silty clay loam; slightly acid; abn1pt,
smooth boundary.
C-37 to 50 inches, dark greenish-gray (5BG 4/1) silty clay
loam; massive; slightly sticky, slightly plastic;
neutral.
The peat ranges from 30 to 40 inches in thickness. More than
50 percent of the peat below a depth of 10 inches was derived
from sedges. The peat is commonly coated with grayish silt
and contains thin strata of silt loam or silty clay loam, but in
places the mineral coatings and strata are absent. Reaction
ranges from strongly acid to medium acid near the surface,
and from slightly acid to neutral below a depth of 10 to 15
inches.
Runoff is very slow on Clunie peat, and a few areas are
subject to occasional flooding. The water table is always
near the surface. The roots of plants can penetrate to a
depth of 15 to 20 inches.
Included with this soil in mapping are a few small
ponds. Also included are patches of peat that are more
than 40 inehes thick, smalll tracts of Salamatof peat, and a
few small areas of greenish-gray tidal sediment.
Clunie peat is used mainly as wildlife habitat, especially
for migratory waterfowl. Management group 27 (VII w-
1).
Coal Creek Series
The Coal Creek series consists of nearly level, poorly
drained soils that formed in deep silty material washed in
from surrounding areas. These soils are on the edges of
muskegs and in shallow depressions on terraces and up-
lands. The vegetation is dominantly tall grasses and scat-
tered sedge tussocks, but black spruce, alder, and willow
grow in a few places. Elevation ranges from 50 to 800 feet.
These soils generally are near well-drained Chulitna,
Nancy, and Rabideux soils and very poorly drained Sala-
matof soils.
In a representative profile a mat of partly decomposed
organic matter about 5 inches thick overlies rvery dark
brown and dark-brown silt loam about 9 inches thick.
Below is dark grayish-brown and olive-gray mottled silt
loam to more than 45 inches.
Most areas of Coal Creek soils are under natural vege-
tation and are used as wildlife habitat.
Coal Creek silt loam (0 to 3 percent slopes) {Co).-
This is the only Coal Creek soil mapped in the survey area.
It is in depressions and along the edges of muskegs.
Representative profile (NE1,4SE% sec. 13, T. 20 N.,
R. 5 W.):
01-5 to 2 inches, very dark brown (lOYR 2/2) mat of partly
decomposed organic matter; many fine roots; strongly
acid: clear, wavy boundary.
02--2 to 0 inches, black (10YR 2/1) finely divided organic mat-
ter ; many roots ; a few pockets of grayish silt ;
strongly acid; clear, wavy boundary.
All-0 to 2 inches, very dark brown (10YR 2/2) silt loam;
weak, fine, granular structure; very friable; a few
black streaks ; many roots ; strongly acid ; clear,
smooth boundary.
A12-2 to 9 inches, dark-brown (10YR 4/3) silt loam; common,
medium, distinct, dark reddish-brown mottles; a few
streaks of dark grayish brown (2.5Y 4/2) ; weak, fine,
granular structure; very friable, smeary when rubbed
between the fingers ; common roots ; strongly acid;
clear, wavy boundary.
01-9 to 20 inches, dark grayish-brown (2.5Y 4/2) silt loam;
patches of olive gray (5Y 5/2) ; common, medium,
prominent, brown (7.5YR 4/4) mottles; weak,
medium, platy structure; nonsticky, nonplastic; a few
roots ; common fine pores ; strongly acid ; gradual
boundary.
02--20 to 45 inches, olive-gray ( 5Y 4/2) silt loam ; a few
streaks of olive brown (2.5Y 4/4)·; a few, medium,
prominent, strong-brown (7.5YR 5/6) mottles; mas-
sive; friable, nonplastic; a few rounded pebbles;
strongly acid.
The A horizon generally is silt loam, but in places it is
mucky silt loam. Under vegetation that is dominantly grasses,
the A horizon generally is between 6 to 12 inches thick, but
under black spruce it is as little as 3 inches thick. The C hori-
zon is dominantly silt loam, but it is likely to contain thin
lenses or a few pockets of fine sand, very fine sand, and silty
clay loam. The silt loam is friable to firm below a depth of 20
inches. Common brown to reddish-brown mottles are through-
out the profile. In a few places rounded stones occur at shallow
or mO'derate depths.
Permeability is moderate in this soil. The water table
generally is below a depth of 30 inches, but it is likely to
rise to a depth of less than 12 inches early in spring or
after periods of heavy rain. Roots can penetrate to a depth
of 20 to 30 inches. Runoff is very slow.
Included with this soil in mapping are a few shallow
soils and stony spots. Also included are small tracts of
Dinglishna and Lucile soils.
All of Coal Creek silt loam is in natural vegetation
and is used as wildlife habitat. Management group 19
(IVw-2).
Delyndia Series
In the Delyndia series are nearly level to hilly, some-
what excessively drained soils on stabilized dunes and
high terraces. These soils formed in deep fine sand 'that
had a mantle of silt loam. The vegetation is paper birch,
white spruce, and quaking aspen. Elevation ranges from
about 25 to 250 feet. Delyndia soils generally are near
Kashwitna and Nancy soils.
In a representative profile a thin mat of forest litter
overlies a layer of light-gray silt loam, about 1% inches
thick, which rests abruptly on a layer of reddish-brown to
strong-brown silt loam about 9 inches thick. Below is dark
yellowish-brown loamy fine sand that extends to a depth
of about 17 inches. The underlying material is olive-brown
fine sand.
Most of the acreage of these soils is wooded, but a few
small areas are cleared and are used for crops. The prin-
cipal crops are hardy vegetables, hay, pasture, oats, and
barley. The wooded areas are used as wildlife habitat.
Delyndia silt loam, nearly level ( 0 to 3 percent slopes)
{DeA).-This soil has the profile described as representa-
tive of the series. It is on high terraces in the southern part
of the .Area.
10 SOIL SURVEY
Representative profile (NE:J4NW:J4 sec. 34, T. 16 N.,
R.5W.):
01-2 inches to 0, dark reddish-brown (5YR 2/2) mat of
partly decomposed forest litter; many roots ; very
strongly acid; abrupt, wavy 'boundary.
A2-0 to 1¥! inches, light-gray (10YR 6/1) silt loam; weak,
very fine, granular structure; very friable; many
roots; very strongly acid; abrupt, wavy boundary.
B21-1lh to 3 inches, reddish-'brown (5YR 4/4) silt loam; a
few patches of dark reddish brown (5YR 3/3); mod-
erate, fine, granular structure; very friable; a few
fine concretions ; many roots ; very strongly acid ;
clear, wavy boundary.
B22-3 to 7 inches, strong-brown (7.5YR 5/6) silt loam;
streaks and patches of brown (10YR 4/3); weak, fine,
granular structure; very friable; common roots; very
strongly acid; abrupt, wavy boundary.
A2b-7 to 8¥! inches, grayish-brown (10YR 5/2) silt loam;
weak, thin, platy structure; very friable; common
roots; very strongly acid; abrupt, wavy boundary.
B2b-8Yl to 11 inches, brown (7.5YR 4/4) very fine sandy
-loam; weak, fine, granular structure; very friable;
common roots; very strongly acid; clear, wavy
boundary.
IIB3b-11 to 17 inches, dark yellowish-brown (10YR 4/4)
loamy fine sand ; a few very weakly cemented streaks
and patches of brown (10YR 4/3); single grain; loose
when disturbed; a few roots; strongly acid; gradual
·boundary.
IIC-17 to 40 inches, olive-brown (2.5Y 4/4) fine sand; a
few streaks of brown (10YR 4/3) to a depth of 30
inches; single grain; loose; a few strata of medium
and coarse sand below a depth of 30 inches; a few
rounded pebbles ; strongly acid.
The mantle of silt loam ranges from about 7 to 12 inches
thick under the leached gray A horizon. The B horizon ranges
from dark yellowish brown to brown in color. In places this
horizon contains a few weakly cemented fragments of dark
reddish brown. In places the substratum contains a few strata
of silt, rounded p~bbles, pockets of coarse sand, and very
weakly cemented •brownish streaks.
Permeability is rapid in this soil, and available moisture
capacity is low. Plant roots can penetrate to a depth of
30 inches. Runoff is slow. Fertility is low.
Included with this soil in mapping are patches of Kash-
witna and Nancy soils. Also included ·are small areas of
moderately well drained Caswell soils, a few areas of un-
dulating Delyndia soils, and scattered wet spots.
Most of this Delyndia .soil is wooded, but a few small
areas ·are cleared and are used for crops. The principal
crops are garden vegetables, perennial grasses, hay, pas-
ture, oats, and barley. The wooded areas are used mainly
as wildlife habitat, but in a few places trees are harvested
to provide logs and fuel for local use. Management group
11 ( IIIs-3) .
Delyndia silt loam, undulating (3 to 7 percent slopes)
(DeB).-This soil is on high terraces and low scattered
dunes in the southern part of the survey area. Slopes are
short.
Permeability is rapid, and available moisture capacity is
low. Plant roots can penetrate to a depth of 30 inches.
Runoff is slow. Fertility is low.
Included with this soil in mapping are patches of Cas-
well, Homestead, Kashwitna, and Nancy soils. Also in-
cluded are a few wet spots and a few areas where slopes
are short and as steep ·as 12 percent.
Most of this Delyndia soil is wooded and is used prin-
cipally as wildlife~itat. In a few places, however, trees
are harvested to provide logs and fuel for local use. A few
cabins and homesteads have been built in widely scattered
areas. Management group 8 (IIIe-3).
Delyndia silt loam, rolling ( 7 to 12 percent. slopes)
(DeC).-This soil occupies a few low knolls and ridges on
terraces and also a few 1ow stabilized dunes.
Permeability is rapid, and available moisture ca;pacity
is low. Plant roots can penetrate to a depth of 30 mches.
Runoff is slow to moderate, and the hazard of water
erosion is moderate. Fertility is low.
Included with this soil in mapping are ·a few very sandy
spots and small undulating tracts. Also included are small
areas of Homestead, Kashwitna, and Nancy soils.
All of this Delyndia soil is wooded and is used mainly
·as wildlife habitat. Management group 8 (IIIe-3).
Delyndia silt loam, hilly (12 to 20 percent slopes)
(DeD).-This soil is in a few small tracts on terraces and
low stabilized dunes.
Permeability is rapid, and available moisture ca;pacity
is low. Plant roots can penetrate to a depth of 30 mches.
Runoff is medium, and the hazard of water erosion is
severe. Fertility is low.
Included with this soil in rna pping are a few very sandy
spots and a few areas where slopes are short and as steep
as 20 to 30 percent. Also included are a few small tracts
of Kashwitna and Nancy soils.
Most of this Delyndia soil is wooded and is used as wild-
life habitat. Management group 17 (IVe-4).
Delyndia.Salamatof complex (0 to 3 percent slopes)
(Dm).-The soils of this complex are near the edges of
several large muskegs in the southern part of the survey
area. About 40 to 50 percent of this unit generally is Delyn-
dia soils, and about 30 to 40 percent is Salamatof soils.
Making up the remainmg percentage are patches of Cas-
well, Dmglishna, and Moose River soils. The Delyndia and
Salamatof soils each has the profile described as repre-
sentative of its respective series.
Delyndia soils ar<l on low knolls that generally range
from 1 to 2 acres in size. The knolls are separated by a net-
work of narrow tracts of Salamatof peats. The Caswell,
Dinglishna, and Modse River soils are in narrow areas be-
tween areas of Delyndia and Salamatof soils.
Delyndia soils are wooded, and the vegetation is domin-
antly paper birch and white spruce. Salamatof peats are
covered by moss, low shrubs, and scattered patches of
stunted black spruce. The soils in this unit are used mainly
as wildlife habitat. Management group 27 (VIIw-1).
Dinglishna Series
In the Dinglishna series are nearly level, poorly drained
soils on or near the edges of large muskegs. These soils
formed in sandy sediment that contains a few strata and
pockets of silty material. The vegetation is dominantly
moss, sedges, low shrubs, and scattered black spruce. Ele-
vation ranges from 25 to 200 feet. These soils generally
are near Delyndia, Moose River, and 1Salam3itof soils.
In a representative profile a mat of partly decomposed
moss and organic material about 4 to 10 inches thick is on
the surface. The upper mineral layer is gray sandy loam,
about 6 inches thick, that rests abruptly on a layer of very
dusky red loamy sand about 8 inches thick. The material
below is very dusky red strongly cemented sand.
All areas of Dinglishna soils are covered by native vege-
tation and are used as wildlife habitat.
SUSITNA VALLEY AREA, ALASKA 11
Dinglishna sandy loam ( 0 to 3 percent slopes) (Dn).-
This is the only Dinglishna soil mapped in the survey area.
It is r._e:c:,:' ':he edges of large muskegs.
Representative profile (1,300 feet south and 600 feet east
of northwest corner of sec. 33, T. 16 N., R. 5 W.) :
01-6 inches to 0, black (10YR 2/1) mat of partly decomposed
moss, leaves, twigs, and other plant parts; many roots;
very strongly acid; abrupt, wavy boundary.
A2-0 to 6 inches, gray (10YR 5/1) sandy loam; massive; fri-
able ; a few roots ; a few pockets of silt loam ; very
strongly acid; abrupt, wavy boundary.
B21-6 to 14 inches, very dusky red (2.5YR 2/2) loamy sand;
single grain; loose; many, fine and medium, hard
concretions; very strongly acid; abrupt, wavy
boundary.
B22-14 to 20 inches, very dusky red (2.5YR 2/2) sand;
strongly cemented; very strongly acid; a few thin
black bands and streaks.
The profile is dominantly sandy throughout, but the upper-
most part contains common pockets and strata of silty mate-
rial. In places a layer of dark silt loam or mucky silt loam
about 3 inches thick underies the mat of organic material. The
A horizon and the uppermost part of the B horizon generally
are churned by frost action. The strongly cemented B22 horizon
generally is more than 6 inches thick and is likely to contain
lenses of loose, gray fine sand.
The strongly cemented material in the lower part of the
subsoil is very slowly permeable. Penetration of plant
roots generally is restricted to the organic mat on the sur-
face, but a few roots can penetrate to a depth of about 12
inches. The water table is near the surface during most
of the growing season, but at times it drops to a depth of
about 12 or 24 inches for short periods. Runoff is very slow,
and occasional ponding occurs in a few places.
Included with this soil in mapping are many patches of
Moose River and Salamatof soils. Also included are a few
small tracts of Caswell and Delyndia soils.
This Dinglishna soil supports vegetation that is used as
wildlife habitat. Management group 24 (VIw-2).
Dinglishna-Moose River complex (0 to 3 percent
slopes) (Dr).-The soils in this complex occupy irregular
patches near the edges of large muskegs. About 30 to 40
percent of this unit generally is Dinglishna soils, and about
20 ~o. 30 percent is Moose River soils. Making up the re-
m~mmg percentage are Salamatof, Caswell, and Delyndia
smls. The Dinglishna and Moose River soils each has the
profile described as representative of its respective series.
Dinglishna soils occupy positions on knolls that are
elevated about a foot above areas of Moose River soils. The
knolls are between ·areas of Moose River soils in small
depressions. Patches of Salamatof peats are in narrow de-
pressions, and irregular tracts of Caswell soils are in
slightly elevated positions. A few spots of Delyndia soils
are on knolls and very narrow ridges.
The soils in this unit are almost treeless, but scattered
black spruce grows in places. These soils generally have
a thick ground cover of moss, low shrubs, sedges, rushes,
and scattered patches of willow and alder brush. The veg-
etation is used mainly as wildlife habitat. Management
group 24 (VI w-2).
Flat Horn Series
The Flat Horn series consists of nearly level to undulat-
ing, well-drained soils on terraces. These soils formed in
stratified silty and fine sandy sediment capped by a mantle
of silt loam. The vegetation is dominantly paper birch and
white spruce. Elevation ranges from 50 to 400 feet. These
so~s generally •are near soils of the Nancy and Delyndia
senes.
In a representative 'Profile a mat of decomposing forest
litter overlies a surface layer of gray silt loam, a;bout 2
inches thick, over reddish-brown to strong-brown silt loam
about 6 inches thick. Below is dark yellowish-brown fine
sandy loam and olive-brown, stratified fine sand ·and silt
that extend to a depth of about 21 inches. The underlying
material is olive, stratified fine sand and silt.
Most areas of Flat Horn soils are wooded and are used
as wildlife habitat and for recreation. A few small areas
have been cleared for cultivation, and the .principal crops
are bromegrass, oats, barley, potatoes, and hardy
vegetables.
Flat Horn silt loam, nearly level ( 0 to 3 percent
slopes) (FhA).-This soil has the profile described as rep-
resentative of the series. It occu'Pies fairly large tracts on
terraces next to major streams in the survey area.
Representative profile (NW1,4SW1,4 sec. 22, T. 20 N.,
R. 6 W.):
01-3 inches to 0, dark reddish-brown (5YR 2/2) mat of partly
decomposed forest litter and moss; many fine roots;
very strongly acid ; abrupt, wavy boundary.
A2---0 to 2 inches, gray (10YR 5/1) silt loam; weak, thin, platy
structure; very friable; many roots; very strongly
acid; ab·vupt, wavy boundary.
B21-2 to 3~ inches, reddish-brown (5YR 4/4) silt loam;
weak, fine, granular structure; very friable ; many
fine roots ; a few fine concretions ; very strongly acid ;
clear, wavy boundary.
B22-3~ to 8 inches, brown (7.5YR 4/4) and strong-brown
(7.5YR 5/6) silt loam; a few small patches of yellow-
ish ·brown ; weak, fine, subangular blocky structure ;
very frill'ble; common roots; strongly acid; abrupt,
wavy boundary.
A2b-8 to 9 inches, grayish-brown (2.5Y 5/2) silt loam; weak,
fine, subangular blocky structure ; friable ; common
roots; strongly acid; abrupt, broken ·boundary.
IIB2b--9 to 15 inches, dark yellowish-brown (10YR 4/4) fine
sandy loam; patches of brown (7.5YR 4/4) and yellow-
ish brown (10YR 5/4); weak, medium, subangular
<blocky structure ; friable ; common roots ; strongly
acid; clear, smooth boundary.
IIB3b-15 to 21 inches, olive-brown (2.5YR 4/4), stratified fine
sand and silt; strata are well sorted and range from :!A,
inch to 2 inches in thickness ; fine sand is single grain,
loose; silt is weak, medium, subangular blocky and is
friable; a few roots; strongly acid; gradual boundary.
IIC-21 to 40 inches, olive (5Y 4/3), stratified fine sand and
silt; strata are well sorted and range from lh inch to
4 inches in thickness; fine sand is single grain, loose;,
silt is massive, :firia1ble; a few weakly cemented streaks
of dark yellowish brown (10YR 4/4) in fine sand; a
few roots to a depth of 30 inches ; strongly acid.
The capping of silt loam ranges from 8 to 15 inches in thick-
ness and overlies stratified silty and sandy sediment. In places
a few pebbles and pockets of coarse sand occur below a depth
of 25 inches.
Permeability and available moisture capacity are moder-
ate in this Flat Horn soil. Roots can penetrate to a depth
of 30 inches. Runoff is slow.
Included with this soil in m3!pping are patches of Nancy,
Caswell, Delyndia, and Schrock soils.
Most of this Flat Horn soil is wooded and is used as
wildlife habitat. Small areas, however, •are cleared and used
as cropland and pasture. The principal crops are brome-
grass, oats, barley, 'Potatoes, and hardy garden vegetables.
Management group 1 (Ilc-1).
12 SOrL SURVEY
Flat Horn silt loam, undulating (3 to 7 percent
slopes) (FhB).-This soil is on broad terraces along the
edges of major streams in the survey area.
Permerubility and available moisture capacity are moder-
ate in this soil. Plant roots can penetrate to a depth of 30
inches. Runoff is slow to medium, and the hazard of water
erosion is slight to moderate.
Included with this soil in mapping are ,patches of Nancy,
Delyndia, Caswell, and Moose River soils. Also included
are a few wet spots and a few soils that have slopes that
range to 12 percent.
Most of this Flat Horn soil is wooded, but several small
tracts are cleared and used as cropland 1and pasture. The
principal crops are bromegrass, oats, barley, potatoes, and
hardy vegetables. The wooded areas are used mainly as
wildlife habitat, though in a few places paper birch and
white spruce are harvested to provide logs ·and fuel for
local use. In addition, a few areas are suitable for limited
recreational uses as sites for camps, cabins, and trails.
Management group 3 (IIe-1).
Gravelly Alluvial Land
Gravelly alluvial land (Gal consists mainly of loose,
coarse, very gravelly and stony, water-laid sediment. It is
on flood plains and low-lying islands along the major riv-
ers and streams of the survey area. In places the sediment
is covered by recent deposits of grayish silty and fine sandy
material. The areas are dissected by many secondary
stream channels and sloughs and generally are flooded
several times a year. Included in mapping are small areas
of Chena and Niklason soils.
Part of Gravelly alluvial land is barren of vegetation,
but willow brush, alder thickets, patches of grass, and
scattered cottonwoods grow in many places. This land type
is used chiefly as wildlife habitat. The willows provide ex-
cellent browse for moose, which frequent the areas in win-
ter. Management group 3'2 (VIII w-1).
Gravel Pits
Gravel pits (Gv) consist of excavations that are more
than 3 acres in size. These,pits generally are well drained,
but a few are intermittently :ponded.
Most areas of Gravel pits are barren of vegetation,
though a few areas support sparse stands of shrubs and
seedling trees. Gravel pits near rivers and streams are often
used as temporary campsites. Areas of Gravel pits that are
less than 3 acres in size are shown on the detailed map by
the conventional symbol for gravel pits. Management
group 31 (VIIIs-1).
Homestead Series
In the Homestead series are nearly level to moderately
steep, well drained and moderately well drained soils that
formed in a thin mantle of silt loam over very gravelly
glacial drift. These soils are on outwash plains and
moraines. The vegetation is dominantly paper birch, white
spruce, and quaking aspen. In a few shallow depressions
where the soils are moderately well drained, the vegetation
consists of black spruce and a ground cover of moss. Eleva-
tion ranges from 100 to 600 feet. These soils generally are
near soils of the Lliciie, Kashwitna, and Jacobsen series.
In a representative profile a mat of decomposing organic
material, about 2 inches thick, overlies a surface layer of
gray silt loam about 1 inch thick. This horizon rests
abruptly on patchy strong-brown and yellowish-brown silt
loam about 6 inches thick. Below is yellowish-brown to
olive-brown gravelly and very gravelly sand.
Most areas of Homestead soils are wooded, but a few
areas are cleared and are used chiefly for hay and pasture.
The wooded areas are used mainly as wildlife habitat,
though in places paper birch and white spruce are har-
vested to provide logs and fuel. Also, a few areas are used
for recreation and as a source of sand, gravel, and road
fill.
Homestead silt loam, nearly level ( 0 to 3 percent
slopes) (HoA).-This soil has the profile described as rep-
resentative of the series. It occupies a few tracts on out-
wash plains.
Representative profile (SWJ4NWJ4 sec. 27, T. 20 N.,
R.4W.):
01-2 inches to 0, dark reddish-brown (5YR 2/2) mat of de-
composing organic material; many fine roots; very
strongly acid; abrupt, wavy boundary.
.A2-0 to 1 inch, gray (10YR 5/1) silt loam; weak, thin, platy
structure ; very friable ; common roots ; very strongly
acid; abrupt, wavy boundary.
B21-1 to 3lh inches, strong-brown (7.5YR 5/6) silt loam;
many large patches of dark yellowish brown (10YR
4/4) ; weak, fine, granular structure; very friable; a
few, fine, dark concretions; common roots; very
strongly acid; clear, wavy boundary.
B22-Blh to 7 inches, yellowish-brown (lOYR 5/4) silt loam;
a few patches of dark yellowish brown ; very weak,
fine, granular structure; very friable; a few rounded
pebbles ; a few small pockets of volcanic ash ; common
roots ; strongly acid; clear, smooth boundary.
IIB3-7 to 11 inches, yellowish-brown (10YR 5/6) gravelly
coarse sand; single grain ; loose; common roots; a few
cobblestones; strongly acid; gradual boundary.
IIC-11 to 28 inches, olive-brown (2.5Y 4/4) very gravelly
sand ; single grain ; loose ; many cobblestones; strongly
acid.
J
The A2 horizon is gray or light gray in color and ranges
from 1 to 2 inches in thickness. The B2 horizon is dark yellow-
ish brown to stron~ brown in color and ranges from 5 to 9
inches in thickness. lin places the B2 horizon is reddish brown.
Mottles occur throughout the profile. The mantle of silt loam
ranges from 5 to 10 inches in thickness. In places a layer of
waterworked sand as much as 15 inches thick is between the
silt loam and the underlying gravelly sand. The underlying
material generally is loose, but in places it is compact and
contains a small amount of finer material.
Permeability is moderate in the silt loam and rapid in
the very gravelly material in the substratum. Available
moisture capacity is low. Plant roots can penetrate to a
depth of 15 inches. Runoff is slow.
Included with this soil in mapping are small tracts
of soils of the Coal Creek, Jacobsen, Kashwitna, Lucile,
and Salamatof series.
Most of thi::: Homestead soil is wooded, but a few areas
are cleared and are seeded to perennial grasses for hay
and pasture. The wooded areas are used chiefly as wildlife
habitat. A few paper birch and white spruce, however,
are harvested for logs. This soil provides recreational
sites for camps, cabins, and trailers. It also is a source
of gravel, sand, and road fill. Management group 16
(IVe-3).
Homestead silt loam, undulating (3 to 7 percent
slopes) (HoB).-A few scattered areas of this soil are on
outwash plains and on low moraines.
SUSITNA VALLEY AREA, ALASKA 13
Permeability is moderate in the surface layer of this
soil, and it is rapid in the substratum. Available moisture
capacity is low.-Plant roots can penetrate to a depth of
15 inches. Runoff is slow, and the hazard of water erosion
is slight.
Included with this soil in mapping are a few small areas
of Coal Creek, Lucile, Jacobsen, and Kashwitna soils.
Most of this Homestead soil is wooded, but small areas
are cleared and are used mainly for hay and pasture. The
wooded areas are used chiefly as wildlife habitat. In places,
however, a few trees are harvested to provide logs and
fuel. Recreational use of this soil is limited to a few cabins,
several temporary campsites, and trails. In addition, areas
of this soil are a source of gravel, sand, and road fill.
Management group 16 (IV e-3).
Homestead silt loam, rolling (7 to 12 percent slopes)
(HoC}.-This soil is on moraines. Slopes are short and
irregular.
Permeability is moderate in the surface layer and rapid
in the substratum. Available moisture capacity is low.
Plant roots can penetrate to a depth of 15 inches. Runoff
is medium, and the hazard of erosion is moderate.
Included with this soil in mapping are a few small
depressions where drainage is poor. Also included are a
few small tracts of Kashwitna soils.
Most of this Homestead soil is wooded, though a few
small areas are cleared and are seeded to perennial grasses
for hay and pasture. The wooded areas are used mainly
as wildlife ha:bitat, but in a few places paper birch and
white spruce are harvested to proVIde logs and fuel. Recre-
ational use of this soil is limited to a few cabins, small
campsites, and trails. In several places the gravelly mate-
rial in the substratum is a source of gravel, sand, and
road fill. Management group 16 (IVe-3).
Homestead silt loam, hilly ( 12 to 20 percent slopes)
(HoD}.-This soil is on a few moraines. Slopes are short
and chOPPY.·
Permeability is moderate in the thin capping of silty
material and rapid in the very gravelly substratum. Avail-
able moisture capacity is low. Plant roots can penetrate to
a depth of 15 inches. Runoff is moderate to rapid, and the
hazard of water erosion is severe.
Included with this soil in mapping are a few moderately
steep slopes and wet spots. Also included are small tracts
of soils of the Kashwitna series.
Most of this Homestead soil is wooded. Several small
tracts, however, are cleared and are used for haY. and
pasture. The wooded areas are used mainly as wildlife
habitat, but in a few places paper birch and white spruce
are harvested to provide logs. Areas of this soil near lakes
are used for recreational cabins and a few campsites. In
addition, the very gravelly material in the substratum is
a source of sand, gravel, and road fill. Management group
21 (VIe-2).
Homestead silt loam, moderately steep (20 to 30
percent slopes) (HoE}.-This soil is on a few moraines.
Slopes are short and choppy.
Permeability is moderate in the thin mantle of silty
material and rapid in the very gravelly substratum.
Available moisture capacity is low. Plant roots can pene-
trate to a depth of 15 inches. Runoff is mpid, and the
hazard of erosion is severe.
Included with this soil in mapping are a few short steep
slopes. Also included are a few small wet depressions.
Most of this Homestead soil is wooded and is used
mainly as wildlife habitat. In a few places~ however, the
very gravelly material in the substratum IS a source of
sand, gravel, and road :fill. Management group 21 (VIe-2).
Jacobsen Series
· In the Jacobsen series are nearly level, poorly drained
soils that formed in very stony silt loam alluvium and
colluvium. These soils are in depressions and in areas
'talong streams, lakes, and muskegs. The vegetation is
dominantly moss, low shrubs, and scattered clumps of
willow, alder, and black spruce. Elevation ranges from
100 to 1,000 feet. These soils generally are near soils of
the Kalifonsky, Salamatof and Slikok series.
In a representative profiie, under a black mat of moss,
roots, and other decomposing organic material, a Jacobsen
soil consists of dark grayish-lirown to dark olive-gray
very stony silt loam that extends to a depth of 27 inches
or more.
Most areas of Jacobsen soils are under vegetation and
are used as wildlife habitat.
Jacobsen very stony silt loam (0 to 3 percent slopes)
(Ja}.-This is the only Jacobsen soil mapped in the survey
area. It is in small scattered depressions and in areas along
small streams, muskegs, and lakes.
Representative profile (SE*NE% sec. 6, T. 24 N.,
R. 4 W.):
01-9 inches to 0, black (10YR 2/1) mat of decomposing moss
twigs, and leaves; many roots; very strongly acid;
clear, smooth boundary.
C1g-0 to 8 inches, dark grayish•brown (2.5Y 4/2) very stony
silt loam; massive; slightly sticky, nonplastic; stones
and cobblestones make up 50 to 70 percent of the soil
mass ; common roots; very strongly acid; gradual
boundary.
C2g-8 to 27 inches, dark olive-gray (5Y 3/2) very stony silt
loam; patches of yellowish brown (10YR 4/4) ; mas-
sive; slightly sticky, slightly plastic; stones and
cobblestones make up 50 to 80 percent of the soil mass ;
a few roots to a depth of 18 inches ; a few pockets of
gravel and san(!.; very strongly acid.
The stones in the silty material are rounded. In places the
texture is very stony loam.
Permeability is moderate in this soil. The water table
generally is at 'a depth of less than 2 feet, and the soil is
moist throughout the growing season. Plant roots can
penetrate t? a ~el?t~ of 1~ inches. R~noff is yery slow.
All of this sOil Ism native vegetatiOn and IS used mainly
as wildlife habitat. Management group 28 (VIIw-2).
Kalifonsky Series
~he Ka~ifonsky series c<.msi~ts of nearly level, poorly
dmmed soils that formed m silty material underlain by
very gravelly sand at a depth of 15 to 30 inches. These
soils are in depressions and in areas between well-drained
soils on uplands and very poorly drained muskegs. The
vegetation is dominantly paper birch, black spruce and
alder. Elev,ation ranges from 200 to 1,000 feet. Thes~ soils
generally are near soils of the Chulitna and Rabideux
series.
In a representative profile a mat of decomposing organic
material, about 4 inches thick, overlies a surface layer of
dark-brown silt loam about 2 inches thick. Below is olive
to olive-gray silt loam that extends to a depth of about 22
14 SOI'L SURVEY
inches. It contains brown and olive-brown patches and
mottles. The underlying material is olive very gravelly
sand.
The acreage of Kalifonsky soils is wooded and is used
as wildlife habitat.
Kalifonsky silt loam (0 to 3 percent slopes) (Ka).-
This is the only Kalifonsky soil mapped in the survey area.
It is in the northern part of the Area in scattered depres-
sions and along the edges of muskegs.
Representative profile ( SW;4SW;4 sec. 17, T. 26 N.,
R. 6 W.):
01--4 inches to 0, dark reddish-brown (5YR 2/2) mat of de-
composing organic material; many roots; very
strongly acid; abrupt, smooth boundary.
A1-0 to 2 inches, dark-brown (7.5YR 3/2) silt loam; weak,
very fine, granular structure; very friable; common
roots ; a few, fine, black concretions ; strongly acid ;
abrupt, wavy boundary.
01-2 to 9 inches, olive (5Y 4/3) silt loam; common, medium
distinct, brown (10YR 4/3) mottles; massive; very
friable; nonsticky, nonplastic; a few roots; strongly
acid; clear, wavy boundary.
02-9 to 22 inches, olive-gray (5Y 5/2) silt loam; common,
medium, distinct, brown (7.5YR 4/4) mottles; a few
streaks and patches of olive brown ; massive; non-
sticky, nonplastic; a few roots; strongly acid; clear,
smooth boundary.
IIC3-22 to 40 inches, olive ( 5YR 4/3) very gravelly sand;
single grain ; loose ; a few subrounded stones; strongly
acid.
The silty material ranges from 15 to 30 inches in thickness
over very gravelly sand or gravelly loamy sand. In places a few
rounded stones occur in the lower part of the silty material.
Permeability is moderate in this soil. Plant roots can
penetrate to a depth of about 25 inches. Runoff is slow.
The water table generally is at a depth between 6 and 40
inches, and the soil is nearly saturated throughout the
growing season. Fertility is low.
Included with this soil in mapping are patches of soils
of ~he Chulitna, Lucile, Rabideux, Salamatof, and Slikok
senes.
This soil is wooded and is used as wildlife habitaL.
Management group 12 (IIIw-1).
Kashwitna Series
In the Kashwitna series are nearly level to steep, well-
drained soils that formed in a thin mantle of silt loam
over very gravelly glacial drift. Some of these soils are
on terraces, and others are on gravelly moraines. The
vegetation is dominantly paper birch, white spruce, and
quaking aspen. Elevation ranges from 150 to 600 feet.
These soils generally are near soils of the Lucile, Home-
stead, and Nancy series.
In a representative profile a mat of decomposing forest
litter and other organic material overlies a surface layer
of gray silt loam about 2 inches thick. The subsoil is dark
reddish-brown to strong-brown silt loam about 7 inches
thick. Below is dark-brown silt loam and dark yellowish-
brown gravelly sandy loam that extend to a depth of about
20 inches. The underlying material is olive very gravelly
sand.
Most of the acreage of Kashwitna soils is wooded, but a
few areas have been cleared for use as cropland. The prin-
cipal crops are bromegrass, oats, barley, and hardy vege-
tables. The woodect""-::treas are used as wildlife habitat.
Recreational uses are lilnited to a few campsites and build-
ings along roadsides. The material in the substratum is a
source of sand, gravel, and road fill.
Kashwitna silt loam, nearly le-vei (0 to 3 percent
slopes) (KsA).-This soil has the profile described as rep-
resentative of the series. It occupies broad tracts on out-
wash plains and high terraces.
Representative profile (NE;4NW;4 sec. 20, T. 22 N.,
R.4W.):
01-3 inches to 0, dark reddish-brown (5YR 2/2) mat of de-
composing forest litter, moss, mycelia, and fine roots;
very strongly acid; abrupt, wavy boundary.
A2-0 to 2 inches, gray (10YR 5/1) silt loam; weak, fine,
granular structure; very friable ; many roots ; very
strongly acid; abrupt, wavy boundary.
B21-2 to 4 inches, dark reddish-brown (5YR 3/4) silt loam;
weak, fine, granular structure; very friable; slightly
smeary when rubbed between the fingers; a few fine
concretions ; many roots ; very strongly acid; clear,
wavy boundary.
B22-4 to 9 inches, strong-brown (7.5YR 5/6) silt loam; a few
patches of brown (7.5YR 4/4); weak, fine, subangular
blocky structure ; friable; common roots; very
strongly acid; abrupt, smooth boundary.
A2b-9 to 10 inches, dark grayish-brown (2.5Y 4/2) silt loam;
weak, thin, platy structure ; friable ; common roots ;
very strongly acid; abrupt, broken boundary.
B21b-10 to 14 inches, dark-brown (7.5YR 3/4) silt loam;
weak, thin, platy structure; friable; common roots;
a few rounded pebbles ; very strongly acid; clear,
smooth boundary.
IIB22b-14 to 20 inches, dark yellowish-brown (10YR 4/4)
gravelly sandy loam; massive; friable; a few roots;
strongly acid; gradual boundary.
IIC-20 to 30 inches, olive (5Y 4/3) very gravelly sand; single
grain ; lOose; a few pockets of brown, weakly cemented
sand ; a few roots to a depth of 24 inches ; strongly
acid. • The mantle of silt loam ranges from 10 to 18 inches in thick-
ness over very gravelly drift.
In the southeastern part of the survey area, along the
boundary of the Matanuska Valley Area, Kashwitna soils
have characteristicEl, that approach those of soils of the Home-
stead series. In the :ml:atanuska Valley Area, Kashwitna soils are
classified as Homestead silt loam. As a result, the names of some
adjoining mapping units in the two areas do not correspond.
Permeability is rrloderate in the mantle of silt loam
and rapid in the very gravelly substratum. Available
moisture capacity is low. Plant roots can penetrate to a
depth of 24 inches. Runoff and fertility are low.
Included with this soil in mapping are patches of soils
of the Caswell, Delyndia, Homestead, Lucile, and Nancy
series. Also included are a few areas of undulating Kash-
witna soils.
Most of this Kashwitna soil is wooded, but a few tracts
are cleared and used as cropland. The principal crops are
bromegrass, oats, barley, and hardy vegetables. The
wooded areas are used mainly as wildlife habitat, though
in places a few paper birch and white spruce are harvested
for local use. Recreational uses include sites for a few
cabins and temporary camps. The very gravelly material
in the substratum is a source of sand, gravel, and road
fill. Management group 9 (IIIs-1). ·
Kashwitna silt loam, undulating (3 to 7 percent
slopes) (KsB).-This soil is on broad terraces.
Permeability is moderate in the mantle of silty material
and rapid in the substratum. Available moisture capacity
and fertility are low. Plant roots can penetrate to a depth
of about 24 inches. Runoff is slow to medium, and the
hazard of erosion is slight to moderate.
Included with this soil in mapping are patches of
t i
SUSITNA VALLEY AR'EA, ALASKA 15
Delyndia, Lucile, and Nancy soils. Also included are a
few wet spots and patches of shallow soils.
Most of this Kashwitna soil is wooded, but a few areas
are cleared and used as cropland. The chief crops are
broroegrass, oats, barley, and hardy vegetables. The
wooded areas are used as wildlife habitat. Recreational
use is limited to sites for a few small camps and cabins.
The very gravelly material in the substratum is a source
of gravel, sand, and road fill. Management group 6
(IIIe-1).
Kashwitna silt loam, rolling (1'7. to 12 percent slopes)
(KsC).-This soil is on moraines and terraces. Slopes gen-
erally are short and choppy.
Permeability is moderate in the mantle of silty material
and rapid in the very gravelly substratum. Available mois-
ture capacity and fertility are low. Plant roots can pene-
trate to a depth of about 24 inches. Runoff is medium,
and the hazard of water erosion is moderate.
Included with this soil in mapping ·are small areas of
Homestead, Lucile, and Nancy soils.
Most of this Kashwitna soil is wooded, but a few areas
are cleared and used as cropland. The principal ·crops are
broroegrass, oats, barley, ·and a few hardy vegetables.
The wooded areas are used as wildlife habitat. Recrea-
tional use is limited to sites for a few cabins, for summer
homes along the shores of streams and lakes, and for
several small camps· along roadsides. The material in the
substratum is a source of sand and gravel. Management
group 6 (Ille-1).
Kashwitna silt loam, hilly (12 to 20 percent slopes)
(KsD).-This soil is on a few hilly moraines. Slopes are
short and irregular.
Permeability is moderate in the mantle of silty material
and rapid in the gravelly substratum. Available moisture
capacity is low. Plant roots can penetrate to a depth of
abo~t 2~ inches. Runoff is rapid, and the hazard of water
eroswn IS severe.
Included with this soil in mapping are small areas of
Homestead and Nancy soils. Also included are a few rood-
erately steep slopes.
Most of this Kashwitna soil is wooded and is used as
wildlife habitat. In places, however, a few trees are har-
vested for local use. Use of the areas for recreational pur-
poses is limited to a few cabins along streams and lake-
shores and to several campsites along roads. The gravelly
material in the substratum is a source of sand, gravel, and
road fill. Management group 15 (IVe-2).
Kashwitna silt loam, moderately steep (20 to 30 per-
cent slopes) (KsE).-This soil is on moraines. Slopes are
short and irregular.
Permeability is moderate in the mantle of silty material
and rapid in the very gravelly substratum. Available mois-
ture capacity is low. Plant roots can penetrate to a depth
of ·af1ou~ 24 inches. Runoff is rapid, and the hazard of
eroswn IS very severe.
Included with this soil in mapping are a few steep
slopes and patches of Homestead and Nancy soils.
Most of this Kashwitna soil is wooded and is used as
~ildlife habitat. In places the material in the substratum
Is a source of sand, gravel, and road fill. Management
group 20 (VIe-1).
Kashwitna silt loam, steep (30 to 45 percent slopes)
(KsF).-Sroall areas of this soil are on moraines and on
terrace escarpments. Slopes are short and steep.
Permeability is moderate in the mantle of silty material
and rapid in the very gravelly substratum. Available mois-
ture capacity is low. Pla;nt roots can penetrate to a depth
of about 24 inches. Runoff is rapid, and the hazard of
water erosion is very severe.
Included with this soil in mapping are patches of Ber-
nice, Homestead, and Nancy soils.
Most of this Kashwitna soil is wooded and is used as
wildlife habitat. Management group 25 (VIIe-1).
Killey Series
In the Killey series are nearly level1 moderately well
drained to somewhat poorly drained soils on flood plains
along streams. These soils formed in stratified silty and
sandy, water-laid sediment about 30 to 40 inches thick over
very gravelly coarse sand. The vegetation generally is
sparse stands of white spruce and cottonwood that have
an undergrowth of willow, alder, and ibluejoint ·grass.
Elevation ranges from 50 to 400 feet. These soils generally
are near poorly drained Moose River soils and small
patches of other soils on flood plains.
In a representative profile a dark mat of decomposing
organic material, about 2 inches thick, overlies a dark-
brown surface layer of silt loam about 3 inches thick. The
underlying roa·terial is mottled olive-brown silt loam and
fine sandy loam that extend to a depth of about 26 inches
and dark grayis:h-lbrown fine sand that ·contains a few
strata of silt. At a depth of about 36 inches is olive-gray
gravelly coarse sand or sand that is free of gravel. All
areas of these soils are wooded and are used as wildlife
hwbita;t.
Killey-Moose River complex (0 to 3 percent slopes)
(Kr).-This mapping unit contains the only Killey soil
mapped in the Area. It consists of soils on flood plains.
About 40 to 50 percent of this unit generally is Killey
soils, and about 30 to 40 J?ercent is Moose River soils in
shallow depressions. Making up roost of the remaining
percentage are small tracts of Coal Creek, Jacobsen,
Slikok, Susitna, and Wasilla soils. Also included are a
few patches of Mixed alluvial land and many abandoned
stream channels, as much as 40 feet wide and several feet
deep, that frequently contain excess water from main
stream channels.
The Killey and Moose River soils each has the profile
described as representative of its respective series.
Representative profile of a Killey soil in an area of Kil-
ley-Moose River complex (SW1,4SW% sec. 32, T. 26 N.,
R. 6 W.):
01-2 inches to 0, dark reddish-brown (5YR 2/2) mat of de-
composing organic material; many fine roots; very
strongly acid; abrupt, wavy boundary.
A1-0 to 3 inches, dark-brown (7.5YR 3/2) silt loam; a few,
medium, faint, dark grayish-brown (10YR 4/2) mot-
tles; weak, fine, granular structure; very friable;
many roots; very strongly acid; abrupt, wavy
boundary.
01-3 to 10 inches, olive-brown (2.5Y 4/4) silt loam; com-
mon, medium, faint, dark grayish-brown (10YR 4/2)
mottles and common, fine, distinct, brown (7.5YR 4/4)
mottles ; weak, fine, subangular blocky structure ; very
friable; a few thin strata of fine sand; common roots;
very strongly acid; gradual boundary.
02-10 to 26 inches, olive-brown (2.5Y 4/4) fine sandy loam;
patches of dark grayish brown (2.5Y 4/2) make up
about 50 percent of the horizon; common, medium, dis-
tinct, brown (7.5YR 4/4) mottles; weak, fine, subangu-
16 SOEL SURVEY
lar blocky ~tructure ; very friable ; a few roots ; very
strongly acid ; clear, smooth boundary.
C3-26 to 36 inches, dark grayish-brown (2.5Y 4/2) fine sand·
a few thin strata of silt; single grain· loose· very
strongly acid; clear, smooth boundary. ' '
IIC4-36 to 44 inches, olive-gray (5Y 4/2) gravelly coarse
sand ; single grain ; loose.
In places the A horizon is sandy loam. Brownish and reddish-
brown mottles and streaks commonly occur below the A hori-
zon. The strata of silty and sandy water-laid sediment vary in
arrangement, number, and thickness. The sediment generally
ranges from 30 to 40 inches in thickness over very gravelly
sand or sand.
Permeability is moderate in the soils of this unit. The
water table is at a depth between 2 and 3 feet during most
of the growing season, and the soils generally are satu-
rated throughout the growing season. In places these soils
are flooded occasionally for short periods. Plant roots can
penetrate to a depth of about 2 feet. Runoff is slow.
The plant cover on these soils varies. Many of the some-
what poorly drained soils have a cover of tall bluejoint
grasses interspersed by clumps of willow and alder. The
moderately well drained soils support cottonwoods white
spruce, and a few paper birch, and the small a;eas of
poorly drained included soils generally have a thick cover
of moss ·and low shrubs. These soils are used mainly as
wildlife habitat. Management group 18 (IV w-1).
Lucile Series
The Lucile series consists of nearly level, moderately
well drained soils in scattered depressiOns on terraces and
moraines. These soils formed in a mantle of silt loam 15
to 30 inches thick over very gravelly sand. The vegetation
is dominantly black spruce. Elevation ranges from 50 to
1,000 feet. These soils generally are near soils of the Home-
stead, Kashwitna, and Nancy series.
In a repr~sentative. profile a mat of decomposing moss
and forest htter overlies a layer of dark-gray, mottled silt
loam about 21h inches thick. Below is mottled dark red-
dish-brown to dark-brown silt loam a:bout 13 inches thick.
The material in the substratum is very gravelly sand.
Most areas of these soils are wooded, but a few areas are
cleared and used as cropland. The principal crops are
bromegrass, oats, barley, and hardy vegetables. The
wooded areas are used ·as wildlife habitat.
Lucile silt loam (0 to 31 percent slopes) (lu).-This is
the only Lucile soil mapped in the Area. It is in shallow
depr~ssional areas scattered throughout terraces and
moraines.
Representative profile (1,100 feet east and 350 feet south
of northwest corner of sec. 30, T. 21 N., R. 4 W.) :
01--4 inches to 0, black (10YR 2/1) mat of decomposing moss
and forest litter ; many roots ; many coarse charcoal
fragments; extremely acid; clear, wavy boundary.
.A.2-0 to 2lh inches, dark-gray (10YR 4/1) silt loam· common
medium, distinct mottles of dark yellowi~h brow~
(10YR 4/4); weak, thin, platy structure; friable;
many roots ; very strongly acid ; abrupt, irregular
boundary.
B21-2lh to 3lh inches, dark reddish-brown (5YR 3/4) silt
loam; many mottles of brown (7.5YR 4/4) and very
dark grayish brown (10YR 3/2); weak, fine, granular
structure ; very friable ; common roots ; many fine con-
cretions; very strongly acid; abrupt, broken boundary.
B22-3lh to ·12 inches, brown (7.5YR 4/4) silt loam· common mediuni;(l~tinct mottles of yellowish red (5YR 4/6)
and a few large patches of brown (10YR 5/3) ; weak,
medium, subangular blocky structure; friable; smeary
when rubb~d between the fingers ; common roots ; very
strongly acid; abrupt, wavy boundary.
.A.2b-12 to 13 inches, dark grayish-brown (10YR 4/2) silt
loam ; weak, fine, subangular blocky structure ; friable ;
small patches of dark yellowish brown (10YR 4/4)
and dark gray (10YR 4/1); many charcoal fragments;
a few roots ; very strongly acid ; abrupt, broken
boundary.
B2b-13 to 16 inches, dark-brown (7.5YR 4/4) silt loam; weak,
fine, granular structure; very friable; smeary when
rubbed between the fingers ; many fine concretions the
size of sand; a few pebbles; a few roots; very strongly
acid; clear, smooth boundary.
IIC-16 to 30 inches, olive-brown (2.5Y 4/4) very gravelly
sand; single grain; compact when in place, loose when
disturbed; gravel in uppermost 10 inches is coated
with iron; a few discontinuous strata of weakly ce-
mented sand ; strongly acid.
A few streaks and pockets of volcanic ash commonly occur
in the silty material. Horizons generally are convoluted and
contain streaks and patches of material from adjoining hori-
zons. In places the evidence of a bisequal profile has been
destroyed, probably as a result of frost action.
Permeability is moderate in this soil, and available
moisture capacity is low to moderate. The cover of moss
keeps this soil moist during most of the growing season.
Plant roots can penetrate to a depth of about 24 inches.
Runoff is slow. Fertility is very low.
Included with this soil in mapping are a few undulating
ar~as and patches of Homestead, Nancy, and Rabideux
SOilS.
Most of this soil is wooded, but a few tracts are cleared
and used as cropland. The principal crops are bromegrass,
oats, barley, and hardy vegetables. The wooded areas are
used as wildlife habitat. Management group 9 (IIIs-1).
•
Mixed Alluvial Land
Mixed alluvial land (Me) is 'On flood plains along sec-
ondary streams. It .eonsists of grayish, medium-textured
to coarse-textured, water-laid sediment that is a few inches
to several feet thick over boulders, stones, and cobble-
stones. The areas arEf nearly level, and in many places they
are dissected by sloughs and small stream channels. In
most places Mixed alluvial land is flooded at least once
each year. The vegetation is dominantly dense thickets of
alder and willow brush, but patches of grass, scattered
stands of cottonwood, and a few paper birch grow in
places.
Included with this land type in rna pping are many small
areas of Chena, Moose River, Niklason, and Susitna soils.
Mixed alluvial land is used chiefly as wildlife habitat.
Management group 29 (VII w-3).
Moose River Series
I~ the _Moose River ~eries ~re nearly level, poorly
dramed soils that formed m stratified sandy and silty sedi-
ment on flood plains along secondary streams. The vege-
tation consists of mosses, sedges, low shrubs scattered
patches of gra~s, and clumps of alder, willow,' and black
spruce. ElevatiOn ranges from 50 to 700 feet. These soils
generally are near soils of the Dinglishna, Killey and
Slikok series. '
In a representative profile a mat of decomposing organic
matter, about 3 inches thick, overlies a surface layer of
dark grayish-brown silt loam about 3 inches thick. Below
SUSITNA VALLEY AREA, ALASKA 17
is dark-gray silt loam and dark greenish-gray, stratified
fine sand and silt. The material generally is gravelly below
a depth of more than 40 inches.
These soils have a cover of plants and are used mainly
as wildlife habitat.
Moose River silt loam (0 to 3 percent slopes) (Mr).-
This is the only Moose River soil mapped in the survey
area. It generally is on flood plains along secondary
streams, but a few areas are on the edges of muskegs.
Representative profile (SW*NW* sec. 32, T. 26 N.,
R. 6vV.):
01-3 inches to 0, black (5YR 2/1) decomposing organic mat-
ter; many roots; strongly acid; clear, wavy boundary.
A1-0 to 3 inches, dark grayish-brown (2.5Y 4/2) silt loam;
weak, thin, platy structure; very friable when moist,
nonsticky and nonplastic when wet ; many roots ;
strongly acid; clear, smooth boundary.
C1g-3 to 6 inches, dark-gray (5Y 4/1) silt loam; moderate,
thin, platy structure; very friable; a few roots;
strongly acid; clear, smooth boundary.
C2g-6 to 42 inches, dark greenish-gray (5GY 4/1) stratified
fine sand and silt; massive; very friable; a few roots
in uppermost part; a few thin strata of coarse sand
and a few pebbles in lower part; strongly acid.
The A1 horizon is dominantly silt loam, but it ranges to
fine sandy loam, and the texture commonly varies within
short distances. The strata of silt and fine sand vary in thick-
ness, number, and arrangement. In places as much as 35 per-
cent of the material below a depth of 20 inches is coarse sand
and gravel. The C horizon ranges from gray to dark greenish
gray or bluish gray in color. Very gravelly sand commonly
occurs below a depth of 40 to 50 inches.
Permeability is moderate in this soil. The water table
generally is near the surface. Plant roots can penetrate
to a depth of about 15 inches. Runoff is very slow, and in
places shallow ponding and flooding occur several times
each year.
Included with this soil in mapping are patches of Ding-
lishna, Jacobsen, Killey, Salamatof, and Slikok soils. Also
included are a few small ponds and many secondary
stream channels and sloughs that carry intermittent flows
of water. In addition, a few small very stony and gravelly
areas are included.
Moose River silt loam has a cover of plants and is used
as wildlife habitat. Management group 24 (VIw-2).
Nancy Series
In the Nancy series are nearly level to steep, well-drained
soils on high terraces and moraines. These soils formed
in 15 to 30 inches of silt loam over very gravelly glacial
drift or fine sand. The vegetation generally is ·paper birch
and white spruce. Elevation ranges from 100 to 1,000 feet.
These soils generally are near soils of the Lucile, Kash-
witna, and Rabideux series.
In a representative profile a mat of decomposing forest
litter •and moss overlies a layer of dark reddish-brown,
yellowish-'brown, and dark yellowish-brown silt loam
rubout 14 inches thick. Below is olive-brown silt loam, about
8 inches thick, over olive-gray sand or very gravelly sand
that extends to a depth of 40 inches or more.
Most of the acreage of Nancy soils is wooded, but a few
areas have been cleared and used for crops and for hay
and pasture. The principal crops are bromegrass, oats,
barley, potatoes, and hardy vegetables. The wooded areas
are used mainly as wildlife habitat, but in a few places
paper birch and white spruce are harvested for local use.
Recreational use is limited to cabins and summer homes
along streams and lakeshores and to a few campsites and
trails. The substratum is a source of sand, .gravel, and road
fill.
Nancy silt loam, nearly level (0 to 3 percent slopes)
(NaA).-This soil has the profile described as repre-
sentative of the series. It occupies broad tracts on high
terraces.
Representative profile ( 400 feet east and 150 feet south
of northwest comer of sec. 20, T. 23 N., R. 4 W.) :
01-172 inches to 0, dark reddish-brown (5YR 2/2) mat of
decomposing forest litter and moss ; many roots; very
strongly acid; abrupt, wavy boundM"y.
A2-o to 172 inches, gray (10YR 5/1) silt loam; streaks and
patches of dark yellowish brown (10YR 4/4); weak,
thin, platy structure; very friable; common roots;
many charcoal fragments ; abrupt, irregular !boundary.
B21-172 to 372 inches, dark reddish-brown (5 YR 3/4) silt
loam; many streaks and patches of brown (7.5YR
4/4) ; weak, fine, granular structure; very friable; a
few very fine concretions ; common roots ; very strongly
acid; clear, wavy boundary.
B22-372 to 9 inches, yellowish-brown (10YR 5/6) silt loam;
massive; very friable; smeM"y when rubbed between
the fingers; admixture of material from the A2 and
B21 horizons ; common roots ; very strongly acid ;
abrupt, wavy boundary.
A2b-9 to 1072 inches, brown (10YR 5/3) silt loam; weak
thin, platy structure; very friable; common roots;
very strongly acid; abrupt, broken boundary.
B2b-1072 to 16 inches, dark yellowish-brown (10YR 4/4) silt
loam; weak, thin, platy structure; very friable; a few
streaks of dark brown (7.5YR 4/4) and a few pockets
of material from the A2b horizon; common roots ·
strongly acid; gradual boundary. '
01-16 to 24 inches, olive-brown (2.5Y 4/4) silt loam; weak,
thin, platy structure; friable; a few roots; fine pores;
strongly acid ; clear, smooth boundary.
IIC2-24 to 40 inches, olive-gray (5Y 4/2) very gravelly sand;
single grain; loose; a few pockets of olive-brown silty
material; many cobblestones; strongly acid.
In most places the horizons are churned and convoluted, and
the color patterns are streaked and patchy, In places a few
pockets of volcanic ash occur in the silty material. Within
short distances the mantle of silty material ranges from 15
to 30 inches in thickness over loose very gravelly sand.
Permeability is moderate in the silty material, and it is
rapid in the very gravelly material in the substratum.
A vailaJble moisture capacity is moderate. Plant roots can
penetrate to a depth of 30 inches. Runoff is slow. Fertility
is low.
Included with this soil in mapping are patches of Coal
Creek, Kashwitna, Lucile, and Rabideux soils. Also in~
eluded are a few small undulating areas where slopes are
very short.
Most of this Nancy soil is wooded, but a few areas are
cleared and used as cropland. The principal crops are
bromegrass, oats, barley, potatoes, and hardy vegetwbles.
The wooded areas are used :as wildlife habitat. Recrea-
tional use is limited to a few campsites, trails, and sum-
mer cabins along lakes and streams. The material in the
substratum is a source of sand, gravel, and road fill. Man-
agement group 2 (IIc-2).
Nancy silt loam, undulating (3 to 7 percent slopes)
(NaB).-This soil is on high terraces and moraines. Slopes
are short and irregular.
Permeability is mod('.rate in the mantle of silt loam and
rapid in the substratum. Available moisture capacity is
moderate. Plant roots can penetrate to a depth of 30 inches.
18 SOIL SURVEY
Runoff is slow to medium, and the hazard of water erosion
is slight to mode:rate. Fertility is low.
II£:Kled with this soil in ma;pping are a few small areas
of Nancy silt loam, rolling. Also included are patches of
Kashwitna, Lucile, and Rabideux soils.
Most areas of this Nancy soi·l are wooded, though a few
areas are cleared for use as cropland. The principal crops
are bromegrass, oats, barley, potatoes, and hardy vege-
ta.bles. The wooded areas are used mainly as wildlife
habitat, ibut in a few places the mature trees are harvested
to provide logs and fuel. Recreational uses are limited
mainly to summer cabins, a few trails, and a few campsites.
The material in the substratum is a source of sand, ·gravel,
and road fill. Management SToup 4 (Ile-2) .
Nancy silt loam, rolling (7 to 12 percent slopes)
(NaC).-This soil is on low moraines. Slopes are short
and irregular.
Permeability is moderate in the mantle of silt loam and
rapid in the very gravelly substratum. Available moisture
capacity is moderate. Plant roots can penetrate to a depth
of about 30 inches. Runoff is medium, and the hazard of
water erosion is moderate. Fertility is low.
Included with this soil in mapping are a few small areas
of Nancy silt loam, hilly. Also included are patches of
Kashwitna and Rabideux soils and a few small poorly
drained depressions.
Most areas of this Nancy soil are wooded, though a few
areas are cleared and used as cropland. The principal
crops are bromegrass, oats, barley, potatoes, and hardy
vegetables. The wooded areas are used mainly as wildlife
haJbita.t, but in places a few trees are harvested to provide
logs and fuel. A few areas provide sites for summer cabins,
trails, and camps. The material in the substratum is a
source of sand, gravel, and road fill. Management group
7 (IIIe-2).
Nancy silt loam, hilly (12 to 20 percent slopes)
(NaD).-This soil is on moraines. Slopes are short and
choppy.
Permeability is moderate in the silt loam and rapid in
the substratum. Available moisture capacity is moderate.
Plant roots can penetmte to a depth of about 30 inches.
Runoff is rapid, and the hazard of water erosion is severe
on areas that have been cleared. Fertility is low.
Included with this soil in mapping are a few areas of
Nancy soils that are moderately steep. Also included are
patches of Kashwitna and Rabideux soils and small scat-
tered depressions where drainage is poor.
Most areas of this Nancy soil are wooded, but a few areas
are cleared and used as cropland. The wooded areas are
used mainly as wildlife habitat, and the cleared areas are
seeded to grass and are used for hay or pasture. Recrea-
tional use is limited to a few cabins, trails, and campsites
near lakes and streams. The gravelly material in the sub-
stratum is used for building roads. Management group 14
(IVe-1).
Nancy silt loam, moderately steep (20 to 30 percent
slopes) (NaE).-This soil is on moraines and terrace
escarpments. Slopes are irregular and generally are less
than 200 feet long.
Permeability is moderate in the silt loam and rapid in
the substratum. Available moisture capacity is moderate.
Plant roots can penetrate to a depth of about 30 inches.
Runoff is rapid,-a.Rd the hazard of water erosion is very
severe in cleared areas.
Included with this soil in mapping are a few areas of
Nancy silt loam, hilly, and scattered depressions where
drainage is poor. Also included are patches of Kashwitna
and Rabideux soils.
Except for a few small areas that have been cleared for
cabin sites, this Nancy soil is wooded and used as wildlife
habitat. The gravelly material in the substratum is a source
of sand, gravel, and road fill. Management group 20
(VIe-1).
Nancy silt loam, steep (30 to 4.5 percent slopes) (NaF).-
This soil is on moraines and terrace escarpments. Slopes
are irregular and generally are less than 300 feet long.
Permeability is moderate in the mantle of silt loam and
rapid in the substratum. Available moisture capacity is
moderate. Plant roots can penetrate to a depth of about 30
inches. Runoff is rapid, and the hazard of erosion is very
severe. Fertility is low.
Included with this soil in mapping are a few areas of
Nancy silt loam, moderately steep. Also included are small
tracts of soils of the Bernice and Kashwitna series.
This Nancy soil is wooded and is used as wildlife habitat.
Management group 25 (VIIe-1).
Nancy silt loam, sandy substratum, nearly level (0
to 3 percent slopes) (NcA).-This soil is on large tracts on
terraces along the edges of the major streams of the survey
area. The substratum is deep fine sand, but the profile
ot~erwise is like that described as representative of the
senes.
Permeability is moderate in the mantle of silt loam and
rapid in the substratum. Available moisture capacity is
moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is slow. Fertility is low.
Included with this '13oil in mapping are patches of Cas-
well, Delyndia, and Rabideux soils.
Most areas of this Nancy soil are wooded, but several
tracts are cleared and are used for crops, hay, and pasture.
The principal crop~ are bromegrass, oats, barley, potatoes,
and hardy vegetables. The wooded areas are used mainly
as wildlife habitat, but in places a few trees are harvested
to provide logs an<l fuel. Recreational use is limited to a
few cabin sites, campsites, and trails. The material in the
substratum is a source of road fill. Management group 2
(Ilc-2).
Nancy silt loam, sandy substratum, undulating (3
to 7 percent slopes) (NcB).-This soil is on broad tracts
on high terraces on the edges of major streams of the sur-
vey area. The substratum is deep fine sand, but the pro-
file. otherwise is like that described as representative of the
series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture capac-
ity is moderate. Plant roots can penetrate to a depth of 30
inches. Runoff is slow to medium, and the hazard of water
erosion is slight to moderate. Fertility is low.
Included with this soil in mapping are small tracts of the
Caswell, Delyndia, Flat Horn, and Rabideux soils. Also
included are a few wet spots.
Most areas of this Nancy soil are wooded, though a few
tracts have been cleared and are used as cropland. The
principal crops are bromegrass, oats, barley, potatoes, and
hardy vegetables. The wooded areas are used mainly as
wildlife habitat, but in a few places paper birch and white
spruce are harvested to provide logs and fuel. Recreational
use includes scattered cabin sites, trails, and one or two
J
SUSITNA VALLEY AREA, ALAS·KA 19
camping sites. The sandy substratum is a source of road
fill. Management group 4 (Ile-2).
Nancy silt loam, sandy substratum, rolling (7 to
12 percent slopes) (NcC).-This soil occupies scattered
areas on. high terraces. Slopes are short and irregular.
The substratum is deep fine sand, but the profile otherwise
is like that described as representative of the series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture capacity
is moderate. Plant roots can penetrate to a depth of 30
inches. Runoff is medium, and the hazard of water erosion
is moderate. Fertility is low.
Included with this soil in mapping are small areas of
the Caswell, Delyndia, Flat Horn, and Rabideux soils.
Also included are a few short, moderately steep terrace
escarpments.
Most areas of this Nancy soil •are wooded, though a few
small areas are cleared and used as cropland. The princi-
pal crops are bromegrass, oats, barley, potatoes, and hardy
vegetables. The wooded •areas are used as wildlife habitat.
Recreational use includes campsites, cabins, and trails. In
a :few places the sandy substratum is used as road fill. Man-
agement group 7 (IIIe--2).
Nancy silt loam, sandy substratum, billy (12 to 20
percent slopes) (NcD).-This soil occupies scattered dis-
sected areas on high terraces near major streams of the
survey area. Except that the substratum is fine sand, the
profile is like that described as representative of the series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture ca-
pacity is moderate. Plant roots can penetrate to a depth of
30 inches. Runoff is rapid, and the hazard of water erosion
is severe in cleared areas. Fertility is low. .
Included with this soil in mapping are small areas of
Bernice, Delyndia, Flat Horn, and Rabideux soils.
Most of this Nancy soil is wooded and is used mainly as
wildlife habitat. Many of the ar~as are used for such rec-
reational purposes ·as cabins, trails, and campsites. Man-
agement group 14 (IVe--1).
Nancy silt loam, sandy substratum, moderately
steep (20 to 30 percent slopes) (NcE).-This soil is on
scattered escarpments, dissected areas, and low sharp
ridges on terraces along the edges of major streams of the
survey area. The substratum is fine sand, but the profile
oth.erwise is like that described as representative of the
senes.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture ca-
pacity is moderate. Plant roots can penetrate to a depth of
30 inches. Runoff is rapid, and the hazard of water erosion
~s severe in areas that lack a cover of vegetation. Fertility
1s low.
Included with this soil in mapping are patches of Ber-
nice, Delyndia, and Rabideux soils. Also included are a
few wet seepage spots.
This Nancy soil is wooded and is used mainly as wild-
life habitat. Managementgroup20 (Vle-1).
Niklason Series
In the Niklason series are nearly level, well-drained soils
that formed in silty and sandy, stratified, water-laid sedi-
ment. These soils overlie loose gravelly material at a depth
of 10 to 30 inches. They are on alluvial plains along major
streams of the survey area. The vegetation is dominantly
large cottonwoods, alders, willows, ·and scattered paper
birch and white spruce. Elevation ranges from 25 to 500
feet. These soils are near soils of the Susitna series.
In a representative profile a thin mat of decomposing
organic matter overlies a layer of dark yellowish-brown
silt loam about 2 inches thick. Below is dark grayish-
brown and olive-gray, stratified fine sandy loam, loamy
fine sand, and silt. The stratified material is about 17 inches
thick over loose very gravelly sand.
Most of the •acreage of Niklason soils is wooded and is
used as wildlife habitat.
Niklason fine sandy loam ( 0 to 3 percent slopes) (Nkl .-
This is the only Niklason soil mapped in the survey area.
Some areas are on alluvial plains along major streams of
the Area, and others are on low-lying islands in the Susitna
River.
Representative profile ( 500 feet northwest of southeast
corner of sec. 10, T. 21 N. R. 5 W.) :
01-1lh inches to 0, very dark brown (10YR 2/2) mat of partly
decomposed forest litter; many roots ; very stronglY
acid; abrupt, wavy boundary.
A1--0 to 2 inches, •dark yellowish-brown (10YR 3/4) silt loam;
weak, fine, granular structure; very friable ; many
roots; strongly acid; clear, smooth boundary.
C1-2 to 12 inches, dark grayish-brown (2.5Y 4/2) fine sandy
•loam; single grain; loose; a few thin strata of silt;
common roots; strongly acid; clear, smooth boundary.
02---12 to 17 inches, olive-gray (5Y 4/2) loamy fine sand; single
grain; loose; a few thin strata of gray silt; common
roots; strongly acid; clear, smooth boundary.
IIC3-17 to 40 inches, olive-gray (5Y 4/2) very gravelly sand;
single grain; loose; many strata of closely packed
cobblestones and coarse gravel; a few stones; strongly
acid.
The A1 horizon ranges from silt 'loam to sandy loam in
texture within short distances. In places the A1 horizon is
absent. The strata in the C horizon vary in number, and they
range from less than an inch to several inches in thickness.
The material commonly contains streaks and patches of dark
buried organic material. Depth to the very gravelly sub-
stratum ranges from 10 to 30 inches within short distances.
Permeability is moderate in the silty sediment and rapid
in the underlymg material. Available moisture capacity is
low to moderate. Plant roots can penetrate to a depth of
20 to 30 inches. Runoff is slow. Floods are rare, but in
places they occur for short periods. Erosion is a hazard
near the banks of streams.
Included with this soil in mapping are patches of
Wasilla and Susitna soils. Also included are a few small
tracts of Gravelly alluvial land. In places this soil is
dissected by small secondary stream channels and sloughs
that carry excess water when the main stream channel is
near capacity.
This soil is wooded and is used mainly as wildlife
habitat. In places a few cottonwoods are harvested for
local use. Management group 10 (IIIs-2).
Rabideux Series
The Rabideux series consists of nearly level to steep,
well-drained soils on terraces, moraines, and low, stabilized
dunes. These soils formed in 15 to 30 inches of silt loam
over deep fine sand or very gravelly sand. The vegetation
is dominantly paper birch, white spruce, and quaking
aspen. Elevation ranges from 300 to 1,300 feet. These soils
are near soils of theN ancy series.
20 SOI'L SURVEY
In a representative profile a thin mat of d ecomposing
· organic matter and many roots overlies a l ayer of light-
gray silt loam about 2 inches thick. The next layers are
dark reddish-brown, reddish-brown, and dark-brown silt
loam and have a combined thickness of about 7 inches.
Below is grayish-brown and brown silt loam to a depth
of about 17 inches. The underlying material is olive-brown
silt loam and olive-gray very gravelly sand.
Most areas of Rabideux soils are wooded, but a few
areas are cleared and used as cropland. The principal crops
are bromegrass, oats, barley, and hardy vegetables. The
wooded areas are used as wildlife h abitat. Recreational
u ses include a few cabins, campgrounds, and trails. The
substratmn is a source of sand, gravel, and road fill.
Rabideux silt loam, nearly level (0 to 3 percent slopes)
(R aA).-This soil has the profile described as representative
of the series. It is on high terraces (fig. 3).
Representative profile (SW%SW1)t, sec. 20, T. 26 N., R.
4 vV.):
01-2 inches to 0, dark reddish-b rown (5YR 2/2) mat of de-
composing organic matter; many fine roots; extremely
acid; clear, wavy boundary.
.A.2-0 to 2 inches, light-g ray (10YR 6/1) silt loam; a few
patches of dark gray (10YR 4/1) and brown (10YR
5/3) ; very thin, platy structure; very friable ; many
roots; very strongly acid; abrupt, irregular boundary.
B21-2 to 2 ¥2 inches, dark reddish-brown (2.5YR 2/2) silt
loam; moderate, fin e, granular structure; very fri-
able; many clark, fine , h ard concretions ; a few weakly
cemented fragments in upper lh inch; common roots;
very strongly acid; clear, wavy boundary.
B22-2% to 5 inches, r eddish-brown (5YR 3/4) silt loam; a
few patches of brown (10YR 5/4); weak, fine , granu-
lar structure; very friable; common roots ; very
strongly acid; clear, irregular boundary.
B3-5 to 9¥2 inches, d a rk-brown (7.5YR 4/4) s ilt loam; many
large patches of yellowish brown (10YR 5/4 and 5/6) ;
weak, fine, granular structure; very friable; slightly
smeary when rubbed between the fingers ; common
roots; very strongly acid, clear, wavy boundary.
A2b-9 % to 12 inches, grayish-brown (2.5Y 5/2) silt loam;
many patches of light olive brown (10YR 5/4) ; weak,
Figure 3.-An area cf Rabideux silt loam, nearly level, on terraces
bordering the Susitna River in the northern part of the survey
area. Mountains of the Alaska Range are in the b ackground.
thin, platy structure ; very friable; a few roots ; very
strongly acid; clear, wavy boundary.
B2b-12 to 16¥2 inches, brown (10YR 4/4) silt loam; a few
large patches of dark brown (7.5YR 4/4); weak, fine
granular structure; very friable; common, fine pores ;
a few roots; strongly acid; clear, wavy boundary.
01-16¥2 to 23 inches, olive-brown (2.5Y 4/4) silt loam; weak,
thin, platy structure; friable; a few roots; strongly
acid ; clear, smooth boundary.
!!02-23 to 48 inches, olive-gray (5Y 4/2) very gravelly sand;
single grain ; loose ; many cobblestones ; a few pockets
of fine sand ; strongly acid.
The s ilty material ranges from 15 to 30 inches in thickness
over very gravelly sand.
Permeability is moderate in the mantle of silt loam
and rapid in the substratum. Available moisture capacity
is moderate. Plant roots can penetrate to a depth of 30
inches . Runoff is slow.
Included with this soil in mapping are a few patches
of shallower soils. Also included are small tracts of Chu-
litna, Kalifonsky, and Nancy soils.
Most of this Rabideux soil is wooded, but several tracts
are cleared and used ·as cropland. The principal crops are
bromegrass, oats, barley, potatoes, and hardy vegetables .
Most of the wooded areas are used as wildlife habitat. In
places, however, a few trees are harvested to provide logs
and fuel. Use of this soil for recreational purposes is
limited to a few lakeshore cabins, trails, and campsites. In
several places the substratum is a source of gravel and road
fill. M·anagement group 2(IIc-2).
Rabideux silt loam, undulating (3 to 7 percent slopes)
(RaB).-This soil is on terraces and low moraines. Slopes
are short and irregular.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
is moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is slow to medium, and the hazard of
water erosion is slight to moderate. Fertility is low.
Included with this soil in mapping are small tracts of
Chulitna, Kalifonsky, and Nancy soils.
Most of this Rabideux soil i s wooded, but a few areas
are cleared and used as cropland. The principal crops are
bromegrass, oats, barley, potatoes, and hardy vegetables.
The wooded areas are used mainly as wildlife habitat. A
few areas are used for lakeshore cabins, campsites, and
trails. The substratum. is a source of gravel and road fill.
Management group 4 (IIe-2).
Rabideux silt loam, rolling (7 to 12 percent slopes)
(RaC).-This soil is on moraines. Slopes are short and
irregular.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
i s moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is medium, and the hazard of water
erosion i s moderate in cleared areas. Fertility is low.
Included with this so il in mapping are small areas of
Chulitna, Kalifonsky, and Nancy soils. Also included are
a f ew areas where slopes are short and are steeper than
those of this soil.
Most areas of this Rabideux soil are wooded, but a few
small tracts are cl eared and u sed as pasture and cropland.
The principal crops are bromegrass, oats, barley, and hardy
vegetables. In a few places the substratum is a source of
gravel and road fill. Management group 7 (IIIe-2).
Rabideux silt loam, hilly (12 to 20 percent slopes)
SUSITNA VALLEY AREA, ALASKA 21
(RaDJ.-This soil is on moraines. Slopes are short and
choppy. b'l't · d t · th il l d ·a · Permea 11 y IS roo era e ill e s t oam an rap1 ill
the very gravelly substratum. Available moisture capacity
is moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is rapid, and the hazard of water erosion
is severe in cleared areas. Fertility is low.
Included with this soil in mapping are small tracts of
Chulitna soils. Also included are a few small depressions
where drainage is poor and a few areas where slopes are
moderately steep.
This Rabideux soil is wooded and is used ·as wildlife
habitat. In a few places the substratum is a source of
gravel and road .fill. Management group 14 (IVe-1).
Rabideux silt loam, moderately steep (20 to 30 percent
slopes) (RaE).-This soil is on moraines. Slopes are short
and irregular.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
is moderate. Plant roots can penetrate to a depth of 30
inches. Runoff is rapid, and the haz·ard of erosion is very
severe on unprotected areas.
Included with this soil in mapping are patches of Chu-
litna soils. Also included are a few areas where slopes are
steep.
This Rabideux soil is wooded and is used as wildlife
habitat. Management group 20 (VIe-1).
Rabideux silt loam, steep ( 30 to 45 percent slopes)
(RaF).-This soil is on moraines. Slopes are irregular and
seldom are more than 300 feet long.
Permeability is moderate in the mantle of silt loam and
rapid in the substratum. Available moisture capacity is
moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is very rapid, and the hazard of water
erosion is very severe.
Included with this soil in mapping are small areas of
Chulitna soils. Also included are a few small tracts of
shallow soils.
.Th~s Rabi.deux soil is wooded and is used mainly as
w1ldhfe hab1tat. Management group 25 (VIIe-1).
Rabideux silt loam, shallow, nearly level (0 to 3
percent slopes) (RbA).-This soil occupies several broad
tracts on high terraces. The mantle of silt loam is 15 to
20 inches thick over the very gravelly substratum, but the
profile otherwise is like that described as represenbative
of the series.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
24 inches. Runoff is slow. Fertility is low.
Included with this soil in mapping are a few patches of
Kashwitna and Nancy soils.
Most of this Rabideux soil is wooded, but a few small
areas are cleared and used 'as cropland and pasture. The
principal crops are bromegrass, oats, barley, and a few
hardy vegetables. The wooded areas are used as wildlife
habitat. In a few places the substratum is a source of gravel
and road fill. Management group 9 (IIIs-1).
Rabideux silt loam, shallow, undulating (3 to 7 per-
cent slopes) (RbB).-This soil occupies a few large tracts
on high terraces. The mantle of silt loam is 15 to 20 inches
thick over the very gravelly substratum, but the profile
otherwise is like that described as representative of the
series.
Permeability is moderate in the silt loam and rapid
in the very gravelly substratum. Available moisture ca-
pacity is low to moderate. Plant roots can penetrate to a
depth of 24 inches. Runoff is slow to medium, and the haz-
ard of erosion is slight to moderate. Fertility is low.
Included with this soil in mapping are 'a few small areas
where the soil is shallower to very gravelly material than
this soil. Also included are small tracts of Kashwitna and
Nancy soils and a few areas where slopes are short ·and
moderate.
Most of this Rabideux soil is wooded, but several small
tracts are cleared and used as cropland. The principal
crops are oats, barley, bromegrass, and hardy vegetables.
The wooded areas are used as wildlife habitat. Scattered
areas provide sites for cabins on lakeshores, trails, and
camps. In several places the material in the substratum is
a source of gravel 'and road .fill. Management group 6
(IIIe-1).
Rabideux silt loam, shallow, rolling (17 to 12 percent
slopes) (RbC).-This soil is in scattered areas on moraines.
Slopes are short and irregular. Depth to gravelly material
is less than in the profile described as representative of the
series, but the two profiles otherwise are similar.
Permeability is moderate in the silt loam and rapid in
the very gravelly subst:vatum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
24 inches. Runoff is medium, and the ha~ard of erosion
is moderate. Fertility is low.
Included with this soil in mapping are patches of Rabi-
deux soils that are underlain by sand. Also included are
a few small tracts of Kashwitna and Nancy soils and a few
wet spots.
Most of this Rabideux soil is wooded and is used as
wildlife habitat. In several places the substratum is a
source of gravel and road .fill. Recreational uses include
a few lakeshore cabins and trails. Management group 6
(IIIe-1).
Rabideux silt loam, shallow, hilly (12 to 20 percent
slopes) (RbD).-This soil occupies scattered tracts on
moraines. Slopes are short and irregular. The mantle of
silt loam is 15 to 20 inches thick over the very gravelly sub-
stratum, but the profile otherwise is like that described
as representative of the series.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
24 inches. Runoff is rapid, and the hazard of water erosion
is severe in cleared areas. Fertility is low.
Included with this soil in mapping are 'a few areas that
are underlain by sand. Also included are a few areas where
slopes are moderately steep and a few small depressions
where drainage is poor.
Most of this Rabideux soil is wooded and is used as
wildlife habitat. In a few places the substratum is a source
of gravel ·and road .fill. Management group 15 (IVe-2).
Rabideux silt loam, shallow, moderately steep (20 to
30 percent slopes) (RbE).-This soil is on moraines. Slopes
are choppy. The mantle of silt loam is 15 to 20 inches thick
over very gravelly material, but the profile otherwise is
like that described as representative of the series.
Permeability is moderate in the silt loam and rapid in
the very gravelly substratum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
22 SOJiL SURVEY
24 inches. Runoff is rapid, and the hazard of water erosion
is very severe. Fertility is low.
Included with this soil in mapping are a few areas where
slopes are 30 to 45 percent. Also included are small areas of
Chulitna soils and a few spots of soil that are underlain by
sand.
Most of this Rabideux soil is wooded and is used mainly
as wildlife habitat. In a few places, however, the gravelly
substratum is a source of road fill. Management group 20
(Vle-1).
Rabideux silt loam, sandy substratum, nearly level
(0 to 3 percent slopes) (RdA).-This soil is on broad ter-
races. It formed in 15 to 25 inches of silt loam over sand,
but its profile otherwise is similar to that described as
representative of the series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substmtum. Availwble moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
30 inches. Runoff is slow. Fertility is low.
Included with this soil in mapping are small tracts of
Chulitna and Nancy soils.
The acreage of this Rabideux soil is wooded and is used
mainly as wildlife habitat. In a few places, however, the
sandy substratum is a source of road fill. Management
group 11 (IIIs-3).
Rabideux silt loam, sandy substratum, undulating
(3 to 7 percent slopes) (RdB).-This soil is on broad ter-
races. Slopes are short and irregular. This soil formed in a
mantle of silt loam 15 to 25 inches thick over sand, but the
profile otherwise is like that described as representative of
the series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
30 inches. Runoff is slow to medium, and the hazard of
erosion is slight to moderate in cleared areas.
Included with this soil in mapping 'are patches of
Chulitna and Nancy soils.
This Rabideux soil is wooded and is used mainly as wild-
life habitat. In places the sandy substratum is used as a
source of road fill. Management group 8 (IIIe-3).
Rabideux silt loam, sandy substratum, rolling (7 to
12 percent slopes) (RdC).-Some areas of this soil are on
scattered stabilized dunes near streams, and others are on
terraces. This soil formed in a mantle of silt loam 15 to 25
inches thick over deep sand, but the profile otherwise is
like that described as representative of the series.
Permeability is moderate in the mantle of silt loam and
rapid in the sandy substratum. Available moisture capacity
is low to moderate. Plant roots can penetrate to a depth of
30 inches. Runoff is medium in cleared areas, and the haz-
ard of water erosion is moderate. Fertility is low.
Included with this soil in mapping are patches of
Chulitna soils. Also included are a few areas where slopes
are short and range from 12 to 20 percent.
This Rabideux soil is wooded and is used as wildlife
habitat. The trees are mainly paper birch and white
spruce. The sandy substratum is a source of road fill.
Management group 8 (IIIe-3).
Rabideux silt loam, sandy substratum, hilly (12 to 20
percent slopes) (RdD).-This soil is on scattered stabilized
dunes along streams and lakes. It formed in silt loam 15 to
25 inches thick o~and, but the pro:file otherwise is rrike
that described as representative of the series.
Permeability is moderate in the silt loam and rapid in
the sandy substratum. Available moisture capacity is low
to moderate. Plant roots can penetrate to a depth of 30
inches. Runoff is rapid, and the hazard of erosinn is severe.
Fertility is low.
Included with this soil in mapping are small areas of
Chulitna soils . .A:lso included are a few ·areas where tho
slope is moderately steep.
This Rabideux soil is wooded and is used as wildlife
habitat. Management group 17 (IVe--4).
Rabideux silt loam, sandy substratum, moderately
steep (20 to 30 percent slopes) (RdE).-This soil is on a
few narrow terrace escarpments. It formed in silt loam
15 to 25 inches thick over deep sand, but the profile other-
wise is like that described as representative of the series.
Permeability is moderate in the silt loam and ralJ?i:d in
the sandy substratum. A 'V'ailable moisture capacity IS low
to moderate. Plant roots can penetrate to a depth of 30
inches. Runoff is rrupid, and the hazard of water erosion 'is
very severe in exposed areas. Fertility is low.
Included with this soH in mapping are a few sandy spots.
Al~o included are a few patches of soils of the Bernice
series.
This Rabideux soil is wooded and is used as wildlife
habitat. Management group 20 (VIe--1).
Salamatof Series
The Salamatof series consists of nearly level, very poorly
drained peat soils in muskegs. The peat material was de-
rived chiefly from sphagnum moss, but partly from sedges.
The vegetati>on is dominantly sphagnum moss, sedges, and
low-growing shrubs, llut stands of stunted, slow-growing
black spruce occur in many places. Elevation ranges from
25 to 1,200 feet. These soils generally are near soils of the
Dinglishna and Jacobsen series.
In a representative profile a 'surface layer of raw sphag-
mun moss 9 inches' thick overlies coarse dark-brown to
brown peat that extends to a depth of 60 inches or more.
The areas of Salamatof soils •are under vegetation and
are used as wildlife 1habitat.
Salamatof peat (0 to 3 percent slopes) (Sa).-This is
the only Salamatof soil mapped in the survey area. It is
in muskegs that range from a few acres to more than 1,000
acres in size.
Representative profile (SE*NE* sec. 22, T. 22 N., R.
6 W.):
Oil-0 to 9 inches, brown (lOYR 4/3), when wet, to pale-
brown (lOYR 6/3) when squeezed dry, raw, unde-
composed sphagnum moss peat; many roots ; many,
dark-colored, coarse woody particles ; extremely acid;
gradual boundary.
Oi2-9 to 60 inches, nark"brown (7.5YR 3/2), when wet, to
brown (7.5YR 4/2) when squeezed dry, coarse moss
peat; a few thin strata of coarse sedge peat; a few
woody particles; a few live roots to a depth of 18
inches ; peat material is slightly finer below a depth
of 24 inches ; extremely acid.
In places the peat material is darker and more finely divided
than that described for the series. Pockets anid very thin lenses
of light-colored volcanic ash and bullied logs are fairly com-
mon in the peat. Near the mouth of the Susitna River, thin
laye11s of silt are in the profile.
The water table generally is at a depth of less than 12
inches in this soi1l. Roots can penetrate to a depth orf less
than 18 inches. Runoff is very slow. Fertility is very low.
SUSITNA VALLEY AR1DA, AL.A:SKA 23
Incl11ded with this soil in mapping are patches of dark
woody peat soils ,and small tmcts of Dinglishna, Jacobsen,
Kalifonsky, and Moose River soils. Also included are many
small shallow ponds. .
This Salamatof soil is under· vegetation and is used as
wildlife habitat. Management group 27 (VIIw-1).
Schrock Series
The Schrock series consists of nearly level, well-drained
soils that formed in silty and sandy aJlluvial sediment.
These soils are on terraces and ·alluvial plains. The vegeta-
tion is dominantly paper birch and white spruce. Elevation
ranges from 100 to 500 feet. These soils generally are near
soils of the Niklason and Susitna series.
In a representative profile a mat of decomposing forest
litter overlies a surface layer of dark-brown silt loam
about 3 inches thick. Beiow is about 5 inches of dark-
brown silt loam streaked with. dark yellowish brown and
aJbout 10 inbhes of olive-brown silt loam that contains a few
strata of fine sand. The underlying material is dark gray-
ish-hrown, stratified silt loam and fine sand.
Most of the acreage of 'Schrock soils is wooded and is
used as wildlife habitat.
Schrock silt loam, nearlylevel (0 to 3 percent slopes)
(ShA).-~his is the <;>nly S~hrock soil mapped in the survey
area. It lS on alluvial plams and low terraces.
Representative profile (NE:JUNW:JU sec. 20, T. 26 N.,
R.4W.):
01-3 inches to 0, dark reddish-brown (5YR 2/2) mat of
decomposing moss, leaves, ·and twigs; many fine roots;
mycelia; extremely acid; clea·r, wavy boundary.
A1-0 to 3 inches, dark-brown (7.5YR 3/2) silt loam; mod-.
erate, fine, granular structure ; very friable ; many
roots; very strongly acid; clear, wavy boundary.
B2-3 to 8 inches, dark-brown (10YR 4/3) silt loam; streaks
of dark yellowish brown (10YR 4/4); weak, fine,
granular structure ; friable; common roots ; very
strongly acid; gradual boundary.
B3-8 to 18 inches, olive-brown (2.5Y 4/4) silt loam; a few
large patches of light olive bro·wn (2.5Y 5/4) and
dark yellowish brown (10YR 4/4) ; weak, thin, platy
structure ; friable; common roots ; a few almost hori-
zontal very dark brown streaks of buried organic
material; a few strata of fine sand that are JU to 72
inch thick; strongly acid; gradual boundary.
C--18 to 42 inches, dark grayish"brown (2.5Y 4/2) stratified
silt loam and fine sand; massive; very friable ; a few
strata of gray, medium and coarse sand; a few
rounded pebbles in lower part ·of horizon ; a few roots
to a depth of 30 inches ; strongly acid.
In places this soil h·as a very thin leached A2 horizon. The
soil material below a depth of 10 inches consists of layered
silt loam and fine sand. These layers range from less than an
inch to several inches in thickness and vary in number and
in arrangement. In most places the sediment is 40 to 60 inches
thick over very gravelly sand.
Permeability and available moisture capaoity are mod-
era~e in this soil. Plant roots can penetrate to a depth of
30 mches. Runoff is slow. Fertility is low.
Included with •this soil in mapping are a few smrull areas
of poorly dra,ined Moose River soils in depressions. Also
inoluded are a few undulating areas and ·a few well-
drained soils that are shallower to gravel than this soil.
All areas of this Schrock soil are rwooded and are used
as wildlife h:abitllit. :Management group 1 (IIc--1).
Slikok Series
The Slikok series consists of nearly levet,q;>Oorly drained
soils that formed in deep mucky silt loam sediment in
depressions, in seepage areas, and along smrull drainage-
ways. The vegetation consists mainly of •alder, willow,
black spruce, moss, and sedges. Elevation ranges from 50
to 1,200 feet. These soils generally are near soils of the Coal
Creek and Jacobsen series.
In a representative profile a !thick mat of organic ma-
terial and about 10 inches of black mucky silt loam overlie
a ·thick dark-gray silt loam :layer.
Slikok soils are under vegetation and ·are used as wildlife
habitat.
Slikok mucky silt loam (0 to 3 percent slopes) (Sm).-
This is the only Slikok soil mapped in the survey area.
It is in depressions and low-lying areas along secondary
streams.
Representative profile (NE1,4SW:JU sec. 12, T. 25 N.,
R. 6 W.):
01-8 to 4 inches, :dark reddish-brown (5YR 2/2) mat of
.coarse decomposing organic material; many roots;
very strongly acid; clear, wavy boundary.
02-4 inches to 0, black (5YR 2/1) finely divided organic
material; a few, coarse, woody fragments; common
roots; very •Strongly acid; clear, wavy boundary.
A1-0 to 10 inches, black (10YR 2/1) mucky silt loam; mas-
:sive; very friable; common roots ; very ·strongly acid;
:gradual boundary.
•c-10 to 50 inches, dark-gray (10YR 4/1) :silt lo·am; many
:pockets of black (10YR 2/1) mucky silt loam; a few
lthin strata of very fine sand ·between a depth of 24
and 50 inches; massive; very fria:ble; a few roots to
a depth of 20 inches ; very strongly acid.
The surface mat of organic material ranges from about 6 to
15 inches in thickness. The C horizon ranges from silt loam
to mucky silt loam in texture. In many places this soil is
underlain by gravelly material at a depth of 40 to 60 inches.
A few spots contain many stones and boulders, which are
.shown on the map by the symbol for stoniness.
The water table generally is near or at the surface of
this soil, but occasionally it drops to a depth of 2 or 3 feet.
Plant roots can penetrate to a depth of 20 inches. Runoff
is slow. ·
Included with this soil in mapping are patches of soils
of the Jacobsen and Moose River series. .
This Slikok soil is under vegetation and is used as wild-
life habitat. Management group 19 (IVw-2).
Susitna Series
In the Susitna series are nearly level, well-drained soils
that formed in stratified silty and sandy sediment laid
down by water. These soils are on broad alluvial plains.
The vegetation in uncleared areas consists of paper birch,
white spruce, cottonwood, and native grasses (fig. 4).
Elevation ranges from 10 to 400 feet. Susitna soils gen-
erally are near Niklason and Schrock soils.
In a representative profile a thin mat of decomposing
·forest litter overlies a layer of dark-gray fine sandy loam
about 3 inches thick. Below is dark-gray layered silt loam,
fine sand, and very fine sand.
Most of the acreage of Susitna soils is wooded, but a few
areas are cleared and are used for hay, small grains, hardy
vegetables, and pasture.
Susitna fine sandy loam (0 to 3 percent slopes) (Ss).-
This soil has the profile described as representative of the
24 SOliL SURVEY
Figure 4.-Bluejoint native grass growing on a Susitna fine sandy
loam.
series. It is on broad alluvial plains along the major
streams of the survey area and on islands in large rivers.
R epresentative profile (NE1;4NE1;4 sec. 27, T '. 22 N., R.
5W.):
01-2 inches to 0, d a rk-brown (10YR 2/2 ) partly decomposed
organic m atter ; many roots ; ver y strongly acid ;
cl ear , smooth botmdary .
A1-0 to 3 inches, very dark gray (10YR 3/1) fine sandy loam;
weak, medium, granul ar structure; very friable; many
roots; very strongly acid; cl ear, wavy boundary.
C-3 to 45 inches, dark-gray (5Y 4/1) silt loam, fine sand,
and ver y fine sand in sorted stratified layer s that
range from less than 1 inch to 5 inches in thickness ;
a few i sol ated patches of very dark brown (10YR
3 /2), buri ed organic material; massive; very friable;
a few roots to a depth of 30 inches ; s trongly acid.
In p l aces the thin dark-colored A horizon is a:bsent. The
texture of the A1 horizon ranges from fine sandy loam to silt
l oam within s hort distances, but it generally is fine sandy
l oam in the uppermost 7 inches. The strata of s ilty and sandy
sediment in t h e C h orizon vary i n number , thickness, and ar-
rangement. The sediment co=only ranges from 40 to GO
inches in thickn ess over ver y gravelly sand.
P ermeability and available water capacity are moderate
in tllis so il. Plant roots can penetrate to a d epth of 30
inches. Runoff i s slow. In places this soil i s flooded occa-
sionally for short periods. Water erosion is a hazard in
areas near rivers and streams.
Included with this soil in mapping are sloughs, aban-
doned secondary channels, and small depressi ons where
drainage is somewhat poor. Also included are patches of
Moose River, Niklason, Schrock, and Wasilla soils.
Most of this Susitna soil is wooded, but a few areas are
cleared and used as cropland. The principal crops are
perennial grasses, oats, barley, potatoes, and hardy vege-
tables. The wooded areas are used mainly as wildlife
habitat, though a few trees are harvested to provide logs
and fuel. Management group 1 (IIc-1).
Susitna and Niklason fine sandy loams, overflow (0 to
3 percent slopes) (Sw).-The soils in this mapping unit are
on flood plains along the major streams of the survey area
and on islands in large rivers. Some areas consist only of
Susitna soils; other areas consist of Niklason soils, and
others are made up of both soils. Each soil has a profile
similar to the one described as representative of its respec-
tive series.
Included with these soils in mapping are patches of
Gravelly alluvial land and Mixed alluvial land. Also in-
cluded are a few small tracts of Chena soils. These areas
generally are dissected by many sloughs and by small
stream cha1mels.
The soils in this unit generally are flooded one or more
times each year for short periods. In places along the banks
of streams the hazard of erosion is severe.
The soils in this unit commonly are wooded, and the
trees are large cottonwoods. In places the understory is a
dense stand of willows that provides habitat for wildlife.
Management group 18 (IVw-1).
Terrace Esca1·pments
Terrace escarpments (T e) consist mainly of silty and
sandy material along flood plains of the Susitna River.
The areas are very steep and are made up of active land-
slides and gullies that are separated by alternate strips and
patches of stabilized areas. The active landslides are almost
bare of vegetation, but willow, alder, and paper birch grow
on most of the stabilized patches. Included in mapping are
a few small areas of Berruce soils and a few wet seepage
spots.
The h azard of water erosion is very severe on Terrace
escarpments. In places flood waters undercut the areas and
cause new l a ndslides and gullies.
Stabilized areas of Terrace escarpments are w ooded and
are used as wildlife habitat. Management group 30
( VIIIe--1) .
Tidal Flats
Tidal flats (Tf) consist of layered tidal d eposits on broad
areas along the edges of Cook Inlet. The flats range from
sand to clay in texture. They are inundated regularly by
high tides. Most areas are bare of vegetation, b ut sparse
stands of beach wild-rye and sedges grow in p l aces. In-
cluded in mapping are a few patches of Tidal marsh,
which occupies higher positions and has a more dense
cover of vegetation than Tidal flats.
Tidal flats are u sed as wildlife habitat, mainly by shore
birds and migratory waterfowl. Management g roup 32
(VIIIw-1).
SUSITNA VALLEY AREA, ALASKA 25
Tidal Marsh
Tidal marsh (T m) consists of nearly level, poorly drained,
bluish-gray, clayey, tidal sediment. It is on plains along
'the edges of Cook Inlet. Althyug~ the areas are !1 few feet
above the level of average high tides, they are mundated
occasionally by exceptionally high tides and by overflow
from fresh-water streams that empty into Cook Inlet. The
vegetation consists of dense stands of grasses, sedges, and
other plants that commonly grow in coastal meadow.
Included with Tidal marsh in mapping are patches of
Clunie peat. Also included are a few moderately well
drained soils on narrow natural levees along small streams.
This land type is used as wildlife habit~t, chiefly ~y
migratory waterfowl and by moose as a calvmg ground m
spring. Management group 23 (VIw-1).
Wasilla Series
In the Wasilla series are nearly level, poorly drained
soils that formed in silt loam and silty clay loam sedim~nt
laid down by water. Some of these soils are on flood plams
along secondary strea;ms, an~ others are in sh~llow. depres-
sions on broad alluvial plams along the maJor nvers of
the survey area. The vegetation is dominantly alder,
willow, and patches of grass, but cottonwood and paper
birch grow in scattered areas. Elevation ranges from 10
to 400 feet. These soils generally are near soils of the Killey
and Susitna series.
In a representative profile a mat of organic matter over-
lies about 2 inches of dark-brown silt loam. The next layer
is mottled very dark grayish-bro~ silt loam about? inches
thick. Below is dark-gray and ohve-gray, layered silt loam
and silty clay loam sediment that contains brownish and
reddish mottles.
Most of the acreage of Wasilla soils is wooded.
Wasilla silt loam (0 to 3 percent slopes) (WaJ.-';['his
is the only Wasilla soil mapped in the survey area. It IS on
flood plains along secondary streams and in shallow de-
pressions on alluvial plains along large rivers.
Representative profile (SW~NE~ sec. 33, T. 16 N., R.
5W.):
01-4 to 2 inches, very dark brown (10YR 2/2) mat olf coarse,
partly decomposed organic matter; many fine roots;
clear, smooth boundary.
02-2 incihes to 0, black (10YR 2/1), finely divided organic
matter; many fine roots; very strongly acid; clear,
smooth boundary.
A1-0 to 2 inches, dark-brown (7.5YR 3/2) sHt loam; mod-
erate, fine, granular structure; slightly sticky, slightly
plastic; many fine roots; strongly acid; abrupt, wavy
boundary.
AC-2 to 7 inches, very dark grayish-brown (2.5Y 3/2) silt
loam ; a few, fine, prominent mottles of yellowish red
(5YR 4/6) ; a few streaks of dark reddish brown;
weak, fine, granular structure; slightly sticky, non-
plastic; common roots; strongly acid; gradual
boundary.
C1g-7 to 13 inches, dark-gray (5Y 4/1) silt loam; common,
medium, distinct mottles of light yellowish brown
(10YR 4/4); weak, thin, platy structure; slightly
sticky, slightly plastic; a few roots ; a few streaks
of dark reddish brown ; strongly acid; clear, smooth
boundary.
IIC2g-13 to 23 inches, dark-gray (5Y 4/1) silty clay loam; a
few, medium, prominent mottles of strong brown
(7 .. 5YR 5/6); patches of olive gray; moderate, thin,
platy structure; moderately firm; slightly sticky,
plastic ; a few roots ; common fine pores ; strongly
acid; clear, smooth boundary.
IIIC3g-23 to 40 inches, olive-gray (5Y 5/2) silt loam, fine
sandy loam, and silty clay loam in stratified ~a~ers
as much as 3 inches thick ; common, coarse, distmct
mottles of dark yellowish brown (10YR 4/4) and a
few, medium, prominent mottles of dark red<l:ish brown
(5YR 3/4); massive; nonsticky, nonplastlc; a few
pockets of sandy clay loam; a few rounded pebbles;
strongly acid.
In places the dark-brown A1 horizon is absent. The silt
loam and silty clay loam water-laid sediment ranges from 40
inches to many feet thick over gravelly material.
Permeability is moderate in the silt loam sediment an~
moderately slow in the silty clay loam layers. Unless arti-
ficially drained, this soil is nearly saturated. throughout
the growing season. The water ta;ble generally IS at a depth
of more than 2 feet, but in places floods occur occasionally
for short periods. Plant roots can penetrate to a depth of
about 24 inches.
Included with this soil in mapping are patches of Killey,
Moose River, and Susitna soils.
Wasilla silt loam is in vegetation and is used as wildlife
habitat. Management group 13 (III w-2) .
Whitsol Series
In the Whitsol series are nearly level to hilly, well-
drained, silty soils on terraces and m?raines. The vege~a
tion is dominantly paper birch and white spruce. ElevatiOn
ranges from about 100 to.SOO feet. These soils. generally are
near soils of the Kashwitna and Nancy senes.
In a representative profile a mat of decomposing moss
and forest litter overlies a gray silt loam layer, about 2
inches thick, that rests abruptly on dark reddish-brown to
strong-brown silt loam about 9 inches thick. Next is dark-
brown yellowish-brown, and olive-brown silt loam that
extends to a depth of ~bout 23 inches. Below is olive silt
loam and olive-gray very fine sandy loam that rests
abruptly on very gravelly sand at a depth of about 44
inches.
Most areas of these soils are wooded and are used as
wildlife habitat, but ·a few areas are cleared 1and used as
cropland. The principal crops are bromegrass, oats, barley,
potatoes, and hardy vegetables.
Whitsol silt loam, nearly level (0 to 3 percent slopes)
(WhA).-This soil has the profile described as repre-
sentative of the series. It is on broad areas on high terraces.
Representative profile (SE~NE~ sec.18, T. 20 N., R. 4
W.; 50 feet northwest of quarter corner marker):
01-3 inches to 0, dark reddish-brown (5YR 2/2), mat of de-
composing moss and fore&t litter; many roots; mycelia;
very strongly acid; abrupt, wavy bo•undary.
A2-0 to 2 inches, gray (10YR 5/1), silt loam; weak, thin,
platy structure ; very friable ; many roots ; charcoal
fragments ; very strongly acid ; abrupt, irregular
boundary.
B21-2 to 4 inches, dark reddish-brown (5YR 3/4), silt loam;
patches of brown (7.5YR 4/4); moderate, fine, granu-
lar structure ; very friable ; common roo1Js ; a few very
fine concretions; strongly acid; clear, wavy boundary.
B22-4 to 11 inches, strong-brown ( 7.5YR 5/6), silt loam ;
streaks and patches of dark bro•wn (7.5YR 4/4) and
yellowish brown (10YR 5/4) ; weak, thin, platy struc-
ture; friable ; slightly smeary when rubbed between
the fingers ; common roots ; strongly acid ; abrupt,
wavy boundary.
26 SO:!'L SURVEY
A2b-11 to 13 inches, grayish-brown (2.5Y 5/2), silt loam;
weak, thin, platy •structure ; friable ; a few roots;
strongly acid ; abrupt, broken boundary.
B2b-13 to 17 inches, dark-brown (7.5YR 4/4) and yellowish-
brown (10YR 4/4), silt loam; convoluted color pat-
tern ; a few patches of material from A2b horizon ;
weak, fine, subangular blocky Sltrucmre ; very friable ;
gritty when rubbed between the fingevs; a few roots;
strongly acid; clear, wavy boundary.
B3b-17 to 23 inches, dark yellowish-brown (10YR 4/4) and
olive-brown (2.5Y 4/4), silt loam; convoluted color
pattern; weak, thin, platy structure; friable; a few
roots ; a few fine pores ; strongly acid; gradual
boundary.
01-23 to 34 inches, olive (5Y 4/3) silt loam; moderate, thin,
platy structure; friable; a few roots; a few fine pores;
strongly acid; clear, smooth boundary.
02-34 to 44 inches, olive-gray ( 5Y 4/2) very fine sandy loam ;
massive; friable; a few ·streaks of olive brown (2.5Y
4/4) ; strongly acid; clear, smooth boundary.
03---44 to 56 inches, olive (5Y 4/3), very gravelly sand; •single
grain ; loose ; a few pockets of ·silt and fine s'and ;
many rounded cobblestones; strongly acid.
In places the B horizon has a patchy or convoluted colox
pattern, but the color generally is fairly uniform <tb.rOIUghout
the horizon. In places the 01 horizon conJtains a few thin strata
of fine sand and very fine ·sand. The mantle of sdlt loam ranges
from 40 to 60 inches in thickness over sand or very gravelly
sand.
Permeability is moderate in this soil, and .a;vailable mois-
ture ·capacity is moderate to high. Plant roots can pene-
trate to a depth of a:bout 30 inches. Runoff is slow. Fertility
is low.
Induded with this soil in mapping are patches orf
Chulitna, Kashwitna, and N arrey soils. Also included are
a few small depressions and undulating areas.
Most of this Whitsol soil is wooded, but ·a few areas are
cleared and used as ·cropland. The principal crops are
bromegrass grown for hay and silage, oats, barley, pota-
toes, and hardy vegetables. The wooded areas are used
mainly as wildlife ha:bitat, but in places paper birch and
white spruce are harvested to provide logs and fuel. Man-
ag_~ment group 2 (IIc-2).
Whitsol silt loam, undulating (3 to 7 percent slopes)
(WhB).-This soil is on terraces and low moraines.
Permerubility is moderate, and availruble moisture capa-
city is moderate to high. Plant roots can penetrate to a
depth of 30 inches. Runoff is slow to medium, and the
hazard of erosion is slight .to moderate. Fertility is low.
Included with this soil in mapping are a few tracts of
Whitsol silt loam, rolling, and patches of Chulitna, Kash-
witna, and Nancy soils. Also included are a few small
depressions where drainage is poo;r.
Most of this Whitsol soil is wooded, but a few areas are
cleared and used as eropland. The principal •crops are
bromegrass grown for hay and silage, oats, barley, pota-
toes, ·and hardy vegetables. 'J1he wooded areas are used
main:ly as wildlife habitat, though in places a few pap&
birch and white spruce are harvested to provide logs and
fuel. Management group 4 (IIe-2).
Whitsol silt loam, rolling (7 to 12 percent slopes)
(WhC).-This soil is on low moraines. Slopes are short and
irregular.
Permeability is moderate, and available moisture capac-
ity is moderate to high. Plant roots can penetrate to a depth
of 30 inches. Runoff is medium, and the hazard of erosion
is moderate. Fertility is low.
Included withthis soil in mapping are patches of
Chulitna and Nancy soils. Also included are a few tracts
of Whitsol silt loam, hilly, and a few small depressions
where drainage is poor.
Most of this Whitsol soil is wooded, but a few areas are
cleared and used as cropland. The principal crops are
browegrass grown .for hay and silage, oats, barley,
potatoes, and hardy vegetables. The wooded areas are used
as wildlife habitat, and a few areas near lakes and streams
are used for recreational cabins and campsites. Manage-
ment group 7 (IIIe-2).
Whitsol silt loam, hilly (12 to 20 percent slopes)
(WhD).-This soil occupies areas on moraines.
Permeability is moderate, and available moisture
capacity is moderate to high. Plant roots can penetrate to a
depth of 30 inches. Runoff is medium to rapid, and the
hazard of erosion is moderate to severe. Fertility is low.
Included with this soil in mapping are patches of
Chulitna and Nancy soils. Also included are a few areas
where slopes are short and moderately steep.
Most of this Whitsol soil is wooded and is used mainly
as wildlife habitat. A few areas near lakes and streams are
used for recreational cabins and campsites. Management
group 14 (IVe-1).
Whitsol silt loam, moderately steep (20 to 30 percent
slopes) (WhE).-A few areas of this soil are on moraines
and terrace escarpments. Slopes generally are short and
irregular.
Permeability and available moisture capacity are
moderate. Plant roots can penetrate to a depth of about
30 inches. Runoff is rapid, and the hazard of erosion is very
severe. Fertility is low.
Included with this soil in mapping are small areas of
Chulitna and Nancy·soils.
All of this Whitsol soil is wooded and is used as wildlife
habitat. Management group 20 (VIe-1).
J
Use and Management of the Soils
This section coniains information concerning the use
and management of soils in the Susitna Valley Area
for crops and pasture, woodland, wildlife, recreation,
and engineering.
Crops and Pasture
This subsection discusses land clearing, fertilizer needs,
and yields of suitable crops. Then the system of capability
classification used by the Soil Conservation Service is
described, and suggested management by groups of soils,
or capability units, is given.
Land clearing
Most of the soils in the Susitna Valley Area are wooded.
If cleared, however, many of these soils are potentially
suitable for crops and pasture. Harvesting the merchant-
able trees before clearing land for crops prevents waste
and facilitates clearing.
The well-drained soils can be cleared at any time of the
year except in winter, when deep snows are a hindrance.
If the soil is not frozen, brush and trees that are left after
logging can be removed by a bulldozer equipped with a
scarifier blade.
'I,.·.
I
I '1 ·~
•!.'
SUSITNA VALLEY AREA, ALASKA 27
If the soil is frozen, brush and trees can be cut by a
bulldozer equipped with a shearing blade. This method
is effective in improving pasture or m clearing light brush
and trees from areas not intended for intensive develop-
ment. In places where trees larger than about 6 inches
in diameter are sheared, however, removing stumps and
heavy roots is difficult and time consuming. After the soil
thaws in spring or in summer, stumps and large roots can
be moved to windrows by a scarifier blade. Small stumps
and roots can be removed by a large breaking plow or a
heavy disk, but this method generally involves the difficult
task of removing many roots and other debris by hand
before the soil can be tilled. If these materials ·are left in
the soil, they decompose slowly, and the larger pieces are
likely to interfere with cultivation for many years.
Freeing roots and stumps of as much soil as possible
before pushing them into windrows for burning IS a sig-
nificant practice to be followed in clearing land in the
Area. This practice is especially important where soils
are shallow to gravel and stones that can interfere with
tillage.
Poorly drained soils generally can be cleared with heavy
equipment if they are frozen or are artificially drained.
Such soils commonly have a thick mat of moss or sedges
on the surface. This mat should be removed during clear-
ing because it tends to prevent the soil from drying.
In undisturbed soils on uplands, organic matter com-
monly concentrates on the surface in a mat that is 2 to 4
inches thick. It is important that some of this material be
left on the surface during land clearing. If the material
is mixed with the underlying mineral soil, it helps to
maintain good soil tilth and to promote infiltration of
water.
Leaving a strip of vegetation of adequate width and
spacing on areas where soil blowing is a hazard helps to
protect the soil from blowing by strong winds.
Keeping windrows and debris intended for burning clear
of wooded areas and brush helps to keep fires from
spreading.
Fertilizer requirements
Good growth of crops in the Area depends largely on
whether the soils are adequately fertilized. Large amounts
of fertilizer that contains nitrogen, phosphorus, and potas-
sium are needed on all of the soils. Nitrogen is especially
needed on newly cleared soils because much nitrogen is
used by bacteria in decomposing the organic material.
Periodic testing of the soil generally is the most efficient
method of determining fertilizer needs. The requirements
depend upon the fertility or tilth of the soil, the need of
the crop, past management, and other factors. On the
basis of experience and research, the Alaska Agricultural
Experiment Station {11) periodically publishes minimum
fertilizer application rates. These rates, provided as a
guide for determining fertilizer needs, are general sugges-
tions and are subject to change.
Under continued cultivation the structure of the soils
in the survey area tends to break down. Adding manure
or other organic material helps to maintain tilth. Most
of the soils are strongly acid or very strongly acid, and
field tests have shown that liming is beneficial for most
crops.
Suitable crops
Only crops that grow in cool climates where the days
in summer are long are adapted to the Susitna Valley
Area. Perennials must be winter hardy ( 5).
Smooth bromegrass is the principal grass crop, but a
variety of timothy developed by the Alaska Agricultural
Experiment Station grows in many places. These peren-
nial grasses provide hay, silage, and pasture. Other peren-
nial grasses that are adapted to the Area include meadow
foxtail, red fescue, reed canarygrass, and Kentucky
bluegrass.
Annual crops suitable for silage are grown from a mix-
ture of oats and peas or of oats and vetch.
Climatically adapted varieties of red clover, alsike
clover, white Dutch clover, sweetclover, and alfalfa, gen-
erally seeded with grasses, are grown, but not extensively.
Spring barley and oats are the main cereal crops. The
harvested grains commonly need artificial drying for safe
storage. The crops generally are sold or are used for live-
stock feed, but the oat varieties adapted to the Area are
suitable for milling, and the barley varieties are suitable
for malting.
Root and leafy vegetables that mature early are espe-
cially well suited to the Area. These crops include potatoes,
carrots, head lettuce, cabbage, radishes, turnips, onions,
garden peas, rutabagas, broccoli, brussels sprouts, cauli-
flower, beets, and celery. Tomatoes, cucumbers, and sweet
corn generally can be grown only in greenhouses.
Several varieties of raspberries, strawberries, and cur-
rants ·are also well suited. Native berries include lingen-
berries, blueberries, raspberries, mooseberries (high:bush
cranberries) , doudberrie'S, and currants. Except for the
Siberian crabapple, fruit trees have not been grown
successfu'lly.
Estimated yields
Estimated average yields ·per acre of principa:l crops
grown on so~ls in the Area are given in table 2. These
estimates are averages expected over several years and 'are
given for two levels of management. The yield'S in columns
A •are expected under average management, and those in
columns B are expected under improved management. The
estimates were made on the basis of ·information from the
Alaska Agricultural Experiment Station, the Alaska
Agricultural Crop Reporting Service {18), agricultural
fieldworkers, and farmers.
Practices and conditions under average management in-
clude the following: (1) Minimum amounts of fertilizer
are applied according to results of occasional soil tests, but
fertiEty is commonly not adequate for optimum plant
growth; (2) sod crops, barnyard manure, and crop residue
are used to a liinited extent, but the quality and quantity
generally are inadequate for the most efficient use of mois-
ture and plant nutrients; ( 3) conservation practices to
control soil blowing and water erosion are applied to a
limited extent, but they generally are not adequate on a:ll
fields; ( 4) weeds and harmful insects are controlled to
some extent on ·cropland, but seldom on pastures; ( 5)
cutting and grazing ·of forage is only partly regulated,
and stands are weakened by overgrazing; (6) artificial
drain!l!ge is ·adequa:te on soils that require it; (7) the soil
reaction generally is below the desirable range for opti-
mum plant growth.
28 SOIL SURVEY
TABLE 2.-Estimated average yields per acre of principal crops under two levels of management
[Yields in columns A can be expected under an average level of management; those in columns B can be expected under improved manage-
ment. Absence of data indicates that the crop is not grown or is not suited to the soil specified. Gravelly alluvial land, Gravel pits,
Terrace escarpments, Tidal flats, and Tidal marsh are not included in this table, because they are not suitable for crops]
Oats
Soil
A B
--
Bu. Bu.
Bernice sandy loam, steep .. -------------------------Caswell silt loam __ -________ -________ -_____ 50 65 Chena fine sandy loam _____________________ --------Chulitna silt loam, nearly leveL. ____________ 50 65 Chulitna silt loam, undulating ______________ 50 65 Chulitna silt loam, rolling __________________ 45 60
Clunie peat. __ ----------------------------Coal Creek silt loam _______________________ --------
Delyndia silt loam, nearly leveL ____________ 45 60 Delyndia silt loam, undulating ______________ 45 60
Delyndia silt loam, rolling ___ -________ -_____ 40 55
Delyndia silt loam, hilly--------------------35 50
Delyndia-Salamatof complex .. __ ---___ ------
Dinglishna sandy loam ________ ----___ ------
Dinglishna-Moose River complex ____________
Flat Horn silt loam, nearly leveL __ ---------55 70
Flat Horn silt loam, undulating _____________ 55 70
Homestead silt loam, nearly leveL .. ---------35 50 Homestead silt loam, undulating ____________ 35 50 Homestead silt loam, rolling ________________ 35 50 Homestead silt loam, hilly __________________
Homestead silt loam, moderately steep _______ --------
Jacobsen very stony silt loam _______________
Kalifonsky silt loam _______________________ 40 55
Kashwitna silt loam, nearly leveL ___________ 40 55
Kashwitna silt loam, undulating ____________ 40 55 Kashwitna silt loam, rolling ________________ 40 55
Kashwitna silt loam, hillY------------------
Kashwitna silt loam, moderately steep _______
35 50
Kashwitna silt loam, steep~----------------Killey-Moose River complex ________________
Lucile silt loam ____________ ---------------40 55
Mixed alluvial land _________ -----------------------Moose River silt loam _____________________ --------
Nancy silt loam, nearly leveL--------------50 65 Nancy silt loam, undulating ________________ 50 65 Nancy silt loam, rolling ____________________ 45 60
Nancy silt loam, hillY---~------------------40 55
Nancy silt loam, moderately steep ___________
Nancy silt loam, steep _____________________ --------Nancy silt loam, sandy substratum, nearly level. __________________________________ 50 65
Nancy silt loam, sandy substratum, undulat-ing ____________________________________ 50 65
Nancy silt loam, sandy substratum, rolling ____ 45 60
Nancy silt loam, sandy substratum, hilly _____ 40 55
Nancy silt loam, sandy substratum, moder-
ately steep ____________ -----------------Niklason fine sandy loam ___________________ 45 60
Rabideux silt loam, nearly leveL ____________ 50 65 Rabideux silt loam, undulating ______________ 50 65
Rabideux silt loam, rolling _________________ 45 60
Rabideux silt loam, hillY-------------------40 55
Rabideux silt loam, moderately steep ________ Rabideux silt loam, steep ___________________________
Rabideux silt loam, shallow, nearly leveL----40 55
Rabideux silt loam, shallow, undulating ______ 40 55
Rabideux silt loam, shallow, rolling __________ 40 55
Rabideux silt loam, shallow, hilly ___________ 35 50
Rabideux silt loam, shallow, moderately steep _________
See footnotes at end of table.
------
Barley Bromegrass-
hay (two
cuttings)
A B
A B
----------
Bu. Bu. Tons Tons
--------------------40 55 2. 0 3. 3
---- ----
1.0 2. 0
40 55 2. 3 3. 5
40 55 2. 3 3. 5
35 50 2. 0 3. 3
--------2. 0 3. 5
35 50 2. 0 3. 0
35 50 2. 0 3. 0
30 45 2. 0 3. 0
25 40 1.3 2. 5
45 60 2. 5 3. 5
45 60 2. 5 3. 5
25 40 1.5 2. 5
25 40 1.5 2. 5
25 40 1.5 2. 5
--------1.2 2. 0
1. 0 1.8
30 45 2. 0 3. 3
30 45 2. 0 3. 0
30 45 2.0 3.0
30 45 1.8 3. 0
25 40 1. 5 2. 5
1.0 2. 0
1.2 2.5
30 45 2. 0 3. 0
--------------------
--------------------
40 55 2. 3 3. 5
40 55 2. 3 3. 5
35 50 2. 0 3. 2
30 45 1. 8 3. 0
1.2 2. 3
--------------------
40 55 2. 3 3. 5
40 55 2. 3 3.5
35 50 2. 0 3. 2
30 45 1.8 3. 0
1. 2 2. 3
35 50 2. 0 3. 0
40 55 2. 3 3. 5
40 55 2. 3 3. 5
35 50 2. 0 3. 3
30 45 1.8 3.0
1.2 2. 3
------------30 45 2. 0 3. 0
30 45 2. 0 3. 0
30 45 1. 8 3. 0
25 40 1. 5 2. 5
1.0 2.0
Silage Potatoes
Pasture
Oats and peas Grass 1 produc-
A B tivity 2
A B A B
------------
Tons Tons Tons Tons Tons Tons
------------------------------------Poor.
8. 0 10. 5 3. 0 4. 7 8. 5 12. 0 Good.
------------2. 0 3. 0 ------------Poor.
8. 5 11. 0 3. 2 5. 0 9. 0 13. 0 Good.
8. 5 11. 0 3. 2 5. 0 8. 5 12. 5 Good.
8. 0 10. 5 3. 0 4. 8 8. 0 12. 0 Good.
------------------Poor.
8. 0 11.0 3. 0 5. 0 ------------Good.
8. 0 10. 5 3. 0 4. 5 7. 5 11. 0 Good.
8. 0 10. 5 3. 0 4. 5 7. 5 11. 0 Good.
7. 5 10.2 3. 0 4. 5 7. 0 10. 5 Good.
6. 8 9. 5 2. 0 3. 5 Fair.
Poor.
Poor.
Poor.
9. 0 12. 0 3. 5 5. 0 9. 0 13. 0 Good.
9. 0 12. 0 3. 5 5. 0 8. 5 12. 5 Good.
6. 0 8. 5 2. 0 3. 2 ------------Fair.
6.0 8. 5 2. 0 3. 2 ------------Fair.
6. 0 8. 5 2. 0 3. 2 ------------Fair.
------------1.8 2. 8 ------------Fair.
------------1.5 2. 5 ------------Fair.
Poor.
8. 0 11. O• 3.0 4. 5 6. 0 9. 0 Good.
7.2 10. 0 3. 0 4. 2 6. 5 10. 0 Good.
7.2 10.0 3.0 4.2 6.5 10. 0 Good.
7. 2 10. 0 3. 0 4.2 6. 5 10.0 Good.
6. 8 9. 5 2. 0 3. 5 ------------Fair. ___ ,. __ 1.5 2. 8 ------------Fair.
Poor.
6. 0 8.5 1.8 2. 8 Good.
7. 5 10.5 3.0 4. 5 7. 0 10.5 Good.
~ Poor. ---------1---------------------------
------------------------------------Fair.
8. 5 11. 0 3. 2 5. 0 8. 5 12. 5 Good.
8. 5 11. 0 3.2 5.0 8.5 12.5 Good.
8. 0 10.5 3.0 4. 8 8. 0 12.0 Good.
7. 0 10.0 2. 3 4.0 ------------Good.
------------1.7 3. 0 ------------Fair.
------------------------------------Poor.
8. 5 11. 0 3. 2 5. 0 9. 0 13. 0 Good.
8. 5 11. 0 3.2 5. 0 8. 5 12. 5 Good.
8. 0 10.5 3. 0 4.8 8. 0 12.0 Good.
7. 0 10. 0 2. 3 4. 2 ------------Good.
------------1.7 3. 0 ------------Fair.
8. 0 10. 5 3. 0 4. 5 7. 5 11.0 Good.
8. 5 11. 0 3. 2 5. 0 8. 5 12. 5 Good.
8. 5 11. 0 3. 2 5. 0 8. 5 12.5 Good.
8. 0 10.5 3. 0 4.8 8. 0 12.0 Good.
7. 0 10.0 2. 3 4.2 ------------Good.
------------1. 7 3. 0 ------------Fair.
Poor.
7. 0 9. 5 2. 8 4.2 6. 5 10. 0 Good.
7. 0 9. 5 2. 8 4. 2 6. 5 10. 0 Good.
7. 0 9. 5 2. 5 4. 0 6. 0 9. 5 Good.
6. 5 9. 0 2. 0 3. 3 ------------Fair.
------------1.5 2. 8 ------------Fair.
SUSITNA VALLEY AREA, ALASKA 29
TABLE 2.-Estimated average yields per acre of principal crops under two levels of management-Continued
Oats Barley Bromegrass-Silage Potatoes
hay (two
I
cuttings) Pasture
Soil Oats and peas Grass 1 produc-
A B A B A B tivity 2
A B A B A B
------------------------
Bu. Bu. Bu. Bu. Tons Tons Tons Tons Tons Tons Tons Tons
Rabideux silt loam, sandy substratum, nearly
45 60 35 50 2. 0 3. 0 7. 2 9. 5 2. 8 4. 2 7. 5 11.0 Good. leveL __ --------------------------------
Rabideux silt loam, sandy substratum, undu-
45 60 35 50 2. 0 3. 0 7. 2 9.5 2. 8 4.2 7. 5 11.0 Good. lating __________________________________
Rabideux silt loam, sandy substratum, rolling_ 40 60 30 50 1. 8 3. 0 7. 0 9. 5 2. 5 4. 0 7. 0 10.5 Good.
Rabideux silt loam, sandy substratum, hilly __ 35 50 25 40 1. 5 2. 5 6. 5 9. 0 2. 0 3. 3 ------------Fair.
Rabideux silt loam, sandy substratum, mod-
1. 0 2. 0 1.5 2. 8 erately steep ___________ ---------________ ------------ ----
------------------------Fair. Salamatof peat ______ ----__________________ ------Schrock silt loam, nearly leveL_ ----________ 55 70 45 60 2. 5 3. 5 9.0 12.0 3. 5 5. 0 9.5 13. 5 Good. Slikok mucky silt loam _____________________ 1.5 2. 5 7. 0 9. 0 2. 0 3. 5 ------------Fair. Susitna fine sandy loam ____________________ 55 70 45 60 2. 5 3. 5 9. 0 12. 0 3.5 5. 0 9. 0 13.0 Good.
Susitna and Niklason fine sandy loams,
2. 0 3.0 overfloW------------------------------------------------------ ------
2. 8 4. 0 ------ ------
Good. Wasilla silt loam __________________________ 45 60 35 50 2. 5 3. 5 8. 0 11. 0 3. 5 5. 0 7. 0 10.5 Good.
Whitsol silt loam, nearly leveL _____________ 55 70 45 60 2. 5 3. 5 9. 0 12.0 3. 5 5.0 9. 5 13.5 Good. Whitsol silt loam, undulating _______________ 55 70 45 60 2. 5 3. 5 9.0 12.0 3. 5 5. 0 9.5 13. 5 Good. Whitsol silt loam, rolling ___________________ 50 65 40 55 2. 5 3.5 8. 5 11.0 -------------------------Good.
Whitsol silt loam, hillY---------------------45 60 35 50 2. 3 3. 3 8. 0 10. 5 ------------------ ------
Good.
Whitsol silt loam, moderately steep __________ 1. 8 3. 0 ------------------------------------Fair.
1 Yields of grass silage are for a second cutting only; first cuttings commonly are harvested for hay.
2 Pasture productivity ratings are based on the number of acres of improved pasture required to produce sufficient forage for one dairy
cow, or an equivalent animal unit, for the entire pasture season under average management. The ratings are as follows: Good, 1 acre or
less; fair, 1 to 2 acres; poor, more than 2 acres.
The following practices and conditions are included un-
der improved management: (1) Fertilizer is applied at
maximum rates determined from periodic soil tests, and
adequate fertility is maintained for optimum p~ant
growth; (2) barnyard manure, crop residue, and grass
crops are used intensively, and sufficient organic matter is
m!llintained for t'he most efficient use of moisture and plant
nutrients; (3) conservation practices are applied to the
fullest extent for contrdl of 13oil Mowing and water ero-
sion; ( 4) weeds and harmful insects are controlled on
crops as well as on pasture; ( 5) cutting and grazing of
forage are carefully managed to maintain vigorous stands;
( 6) artifici:al drainage is adE~guate on soils th!lit require it;
(7) if necessary, lime is apphed at rates required to bring
the soil reaction within the range that is most desirable
for optimum plant growth.
Capability grouping
Capability grouping shows, in a general way, the suita-
bility of soils for most kinds of fie'ld crops. The groups
are made according to the limitations of the soils when
used for field crops, the risk of damage when they are
used, and the way they respond to treatment. The grouping
does not take into account major and generally expensive
landforming that would change slope, depth, or other
characteristics of the soils; does not take into considera-
tion possible but mrlikely major recl~mation projects;
and does not app1y to cranberries, horticultural crops, or
other crops r~9.uiring special manag~ment. . .
Those fannhar w1th the capability classificatiOn can
infer from it much about the behavior of soils when used
for other purposes, but this classification is not a substitute
for interpretations designed to show suitability and limita-
tions of groups of soils for :vange, for forest trees, or for
engineering.
In the capability system, all kinds of soil are grouped at
three ~evels, the caprubility class, subclass, and unit. These
are discussed in the following paragraphs.
CAPABILITY CLASSEs, the broadest groups, are designated
by Roman numerals I through VIII. The numerals indi-
cate progressively greater limitations and narrower choices
for practical use, defined as follows :
Class I soils (none in Area) have few limitations that
restrict their use.
Class II soils have moderate limitations that reduce
the choice of plants or that require moderate con-
servation practices.
Class III soils have severe limitations that reduce the
choice of plants, require special conservation
practices, or both.
Class IV soils have very severe limitations that reduce
the choice of plants, require very careful man-
agement, or both.
Class V soils (none in Area) are not likely to erode
but have other limitations, impractical to remove,
that limit their use largely to pasture, range,
woodland, or wildlife.
Class VI soils have severe limitations that make them
generally unsuited to cultivation and limit their
use largely to pasture or range, woodland, or
wildlife.
I -
30 .SOIL SURVEY
Class VII soils have very severe limitations that make
them unsuited to cultivation and that restrict
their use largely to pasture or range, woodland,
or wildlife.
Class VIII soils and landforms have limitations that
preclude their use £or commercial plants and
restrict their use to recreation, wildlife, or water
supply, or to esthetic purposes.
CAPABILITY SUBCLASSES are soil groups within one class;
they are designated by adding a small letter, e, 1-o, s, oro,
to the class numeral, £or example, lie. The letter e shows
that the main limitation is risk o£ erosion unless close-
growing plant cover is maintained; w shows that water
in or on the soil interferes with plant growth or cultivation
(in some soils the wetness can be partly corrected by artifi-
cial drainage) ; s shows that the soil is limited mainly
because it is shallow, droughty, or stony; and o, used in
only some parts o£ the United States, shows that the chie£
limitation is climate that is too cold or too dry.
In class I there are no subclasses, because the soils o£
this class have £ew limitations. Class V can contain, at the
most, only the subclasses indicated by w, s, and o, because
the soils in class V are subject to little or no erosion, though
they have other limitations that restrict their use largely
to pasture, range, woodland, wildlife, or recreation.
CAPABILITY UNITS are soil groups within the subclasses.
In this survey they are designated management groups.
The soils in one capability unit are enough alike to be
suited to the same crops and pasture plants, to require
similar management, and to have similar productivity and
other responses to management. Thus, the capability unit
is a convenient grouping £or making many statements
about management o£ soils. Capability units are generally
designated by adding an Arabic numeral to the subclass
symbol; £or example, IIe-1 or IIIs-2. Thus, in one symbol,
the Roman numeral designates the capability class, or
degree o£ limitation; the small letter indicates the sub-
class, or kind o£ limitation, as defined in the foregoing
paragraph; and the Arabic numeral specifically identifies
the capability unit within each subclass. In this survey the
capability unit numbers are in parentheses following the
management group numbers.
Management groups
In the pages that follow, management groups o£ the
Susitna Valley Area are described, and suggestions are
given £or the use, management, and conservation o£ the
soils in each group. The names o£ soil series represented in
a management group are mentioned in the description o£
each group, but this does not mean that all soils in a given
series are in the group. To find the names o£ all the soils
in any management group, refer to the "Guide to Mapping
Units" at the back o£ this survey.
Fertilizer is needed and lime is beneficial £or most o£ the
soils in management groups 1 through 19. Lime and fer-
tilizer, however, should be added to the soils in accordance
with the needs indicated by tests and field trials. No specific
recommendations are made as to the amounts and kinds o£
fertilizer needed, the most suitable crop varieties, or the
best seeding rates, because these elements change as new
developments OOGUJ:. in £arming. Current information and
recommendations are available £rom the local Extension
Service agent and £rom the Alaska Agricultural Experi-
ment StatiOn.
MANAGEMENT GROUP 1 (Ilc-1)
This group consists o£ nearly level, well-drained soils
o£ the Flat Horn, Schrock, and Susitna series. These soils
formed in deep silty and sandy sediment laid down by
water. Most o£ these soils are on alluvial plains and low
terraces.
Permeability and avail<able moisture capacity are mod-
erate in these soils. The soils are very strongly acid near
the surrace and strongly acid in the subsoil. Fertility is low.
Plant roots generally can penetrate to a depth o£ 30 inches.
Runoff is slow, and the hazard o£ erosion generally is
slight, but in places along the river streambank erosion
occurs.
Most o£ the acreage o£ these soils is wooded. A £ew areas
have been cleared £or cultivation, and the principal crops
are bromegrass, barley, oats, potatoes, and hardy garden
vegetables.
Organic matter is needed to help keep these soils in
good tilth and to promote efficient use o£ moistmre and
plant nutrients. Returning crop residue to the soil, adding
manure, and including grasses and legumes in the cropping
sequence are ways to help maintain the content o£ organic
matter. Leaving a border o£ native vegetation along un-
st3!ble streambanks in areas cleared £or cultivation helps to
control accelerated erosion.
MANAGEMENT GROUP 2 (IIc-2)
In this group are nearly level, well-drained silt loams o£
the Ohulitna, Nancy, Rabideux, and Whitsol series. These
soils formed in mo~erately deep and deep wind-laid silt
over very gravelly or sandy material. They are on terraces.
PermeabiHty is moderate in the silty material, and av·ail-
able moisture capacity is moderate to high. These soils are
strongly 1acid to very strongly acid. Fertility is low. Plant
roots can penetrate to a depth o£ about 30 inches. Runoff is
slow, and the hazard o£ erosion is slight.
Most o£ the acr~age o£ the soils in this group is wooded,
but scattered tradts are cleared £or crops. The principal
crops are bromegrass, barley, potatoes, and hardy
vegetaNes.
Organic matter is needed to help keep these soils in good
tilth 1and to promote efficient use o£ moisture and plant
nutrients. Returning crop residue to the soil, adding
manure, and including grasses and legumes in the cropping
sequence are ways to help maintain the content o£ or-
ganic matter. In places shallow drainage ditches or fill ma-
terials are needed to remove excess water £rom wet spots.
MANAGEMENT GROUP 3 (Ile-1)
Only Flat Horn silt loam, undulating, is in this group.
This well-drained soil is on terraces. It formed in a mantle
o£ silty material underlain by stratified fine sand and silt.
Permeability is moderate in this soil, and available mois-
ture capacity is modemte. This soil is strongly acid, and
fertility is low. Plant roots can penetrate to a depth o£ 30
inches. Runoff is slow to medium, and the hazard o£ water
erosion is slight to moderate.
Most o£ the acreage o£ this soil is forested. A £ew acres,
however, have been cleared £or culthnation, and the prin-
cipal crops. are bromegrass, barley, potatoes, and hardy
vegetables.
SUSITNA VALLEY AREA, ALASKA 31
Organic matter is needed to keep this soil in good tilth
and to promote efficient use of moisture and p1ant nutrients.
Returning crop residue to the soil, adding manure, and
including grasses and legumes in the cropping system are
ways tO help maintain the content of organic matter.
Farming on the contour, using grassed waterways, and
growing grass crops help to control erosion.
MANAGEMENT GROUP 4 (IIe-2)
This group consists of undulating, well-drained silt
Ioams of the Chulitna, Nancy, Raibideux, and Whitsol
series. These soils are moderately deep to deep over very
gravelly or sandy mate6al. They are on terraces.
Permeability is moderate in the silty material, and avail-
able moisture capacity is moderate to high. These soils are
strongly acid to very strongly acid. Fertility is low. Plant
roots generally can penetrate to a depth of 1about 30 inches.
Runoff is slow to medium, and the hazard of water erosion
is slight to moderate.
Most of the acreage of the soils in this group is wooded,
but a few areas are cleared for ruse as cropland. The major
crops are bromegrass, barley, oats, potatoes, and hardy
vegetables.
Organic matter is needed to help keep these soils in
good tilth and to promote efficient use of moisture and
plant nutrients. Returning crop residue to the soil, adding
manure, and including grasses and legumes in the cropping
sequence are ways to help maintain the content of organic
matter. Farming on the contour, using grassed waterways,
and growing grasses in the rotation are practices that help
to control water erosion. In pl,aces shallow drainage ditches
or fill materials are needed to remove excess water from
wet spots.
MANAGEMENT GROUP 5 (llw-1)
Only Caswell silt loam is in this group. This nearly
level, moderately well drained soil is in depressions and
along the edges of muskegs. It formed in moderately deep
silty and sandy sediment over very gravelly ma·teriaL
Permeability and available moisture capacity are mod-
erate in this 'Soil. The soil is strongly aoid to very strongly
!l!cid. Fertility is low. Plant roots min penetrate to a depth
of 30 ·inches. Runoff is slow, and rthe hazard of erosion is
slight.
Most of Caswell silt 'loam is wooded, but it is suitable for
:farming. All crops adrupted to the Area are suited. IIi
places drainage ditches would likely be needed to remove
excess water. Returning crop residue to the soil, adding
manure, and including grasses in the cropping sequence
are ways to help maintain the content of organic matter
needed to keep this soil in good Wth and to promote effi-
cient use of plant nutrients.
MANAGEMENT GROUP 6 (llle-1)
This group consists of undulating and roliJ.ing, w~ll
drained silt loams of the Kashwitna and Rabideux series.
These soils are shallow to very gravelly material. They are
on uplands.
Permeability is moderate in the uppermost part of these
soils and rapid in the lower part. Available moisture ca-
pacity is 'low to moderate. These soils 'are strongly acid to
very strongly acid. Fertility is low. Plant roots can pene-
trate to a depth of about 24 inches. Runoff is slow to
medium, and the hazard of erosion is slight to moderate.
Most of the acreage of these soils is wooded, though a
4M-728-Ii3-3
few areas are cleared ,and are used for crops. The principal
crops are bromegrass, barley, oats, potatoes, and hardy
vegetables.
Organic matter is needed to help keep ·these soils in good
tilth and to promote efficient use of moisture and plant
nutr,ients. Returning crop residue to the soil, adding
manure, and including grasses and legumes in the crop-
ping sequence are ways to help maintain the content of
organic matter. Farming on the contour, using grassed
waterways, contour stripcropping, and growing grasses
in the rotation are practices that help to reduce washing
and to keep gullies from forming.
MANAGEMENT GROUP 7 (llle-2)
In this group are rdlling, well-drained silt loams of the
Chulitna, Nancy, Rabideux, and Whitsol series. These
soils are moderately deep and deep over very gravelly ma-
terial and are on uplands.
Permeability is moderate in the silty material. A vaiJ.able
moisture capacity is moderate to high. These soils are
strongly acid to very strongly acid. Fertility is low. Plant
roots can penetra;te to a depth of about 30 inches. Runoff
is medium, and the haZJard of water erosion cis moderate.
Most of the 'aCl·eage of the soils in this group is wooded,
but a few areas are cleared and are used for crops. The
principal crops are bromegrass, barley, oats, potatoes, and
hardy vegetables.
Returning crop residue to the soil, adding manure, and
including grasses in the cropping sequence are ways to
help maintain the content of organic matter needed to
keep these soils in good tilth. Farming on the contour,
using grassed waterways, and growing grass crops in the
rotation are practices that help to contro'l water erosion.
MANAGEMENT GROUP 8 (llle-3)
In this group are undulating and rolling, well-drained
and excessively drained silt loams of the Delyndia and
Rabid.eux series. These soils formed in a mantle of silty
matenal over deep fine sand. They ~are on uplands.
Permeability is moderate in the uppermost part of these
soils and rapid in the sandy material. AvailaJble moisture
capacity is low to moderate. These soils are very strongly
acid. Fertility is low. Plant roots can penetrate to a depth
of 30 inches. Runoff is slow to medium, and the hazard o:f
erosion is slight to moderate.
Most of the acreage of these soils is wooded, but a few
areas are cleared and are used for crops. The principal
crops are bromegrass, barley, oats, potatoes, and hardy
vegetables. During seasons of low rainfaH, or if rain is
poorly distributed, yields are likely to be lowered by
shortage of moisture. Consequently, organic matJter is
needed to promote efficient use of moisture in these soils.
Returning crop residue 'to the soil, adding manure, and
including grasses in the cropping sequence are ways to
help to maintain the content of organic matter. Using
grassed waterways and :farming on the contour are prac-
tices that help to control water erosion.
MANAGEMENT GROUP 9 (IIIs-1)
In this group are nearly level, well drained and moder-
ntely well drained silt Joams of the Kashwitna, Lucile, and
Rabideux series. These soils are shallow over very gravelly
material. They are on uplands.
Permeability generally is moderate in the uppermost.
32 SOIL SURVEY
part of these soils and rapid in the very gravelly sub-
stratum. Available moisture capacity is low to moderate.
These soils are very strongly acid. Fertility is low. Plant
roots can penetrate to a depth of about 24 inches. Runoff is
slow, and the hazard of water erosion is slight.
Most of the acreage of the soils in this group is wooded,
but a few areas are cleared and are used for crops. The
principal crops are bromegrass, barley, oats, potatoes, and
hardy vegetables.
Organic matter is needed to help keep these soils in good
tilth and to promote efficient use of moisture and plant
nutrients. Returning crop residue to the soil, adding
manure, and including grasses in the cropping sequence are
ways to help maintain the content of organic matter.
MANAGEMENT GROUP 10 (llls-2)
Only Nihlason fine sandy loam is in this group. This soil
is nearly level, well drained, and shallow to moderately
deep over very gravelly material. It is on alluvial plains
along the banks of rivers and streams.
Permeability is moderate in the uppermost part of this
soil and rapid in the very gravelly substratum. Available
moisture capacity is low to moderate. This soil is strongly
acid. Plant roots can penetrate to a depth of 20 to 30 inches.
Runoff is slow. The hazard of erosion is slight, except in
places along rivers where streambanks commonly are
undercut and washed away.
Niklason fine sandy loam is wooded, but it is suitable for
cultivation. All crops adapted to the Area are suited.
Organic matter is needed to help keep this soil in good
tilth and to promote efficient use of moisture and plant
nutrients. Returning crop residue to the soil helps to
maintain the content of organic matter. Leaving areas next
to streams in vegetrution helps to control water erosion.
MANAGEMENT GROUP 11 (llls-3)
In this group are nearly level, well-drained and some-
what excessively drained silt loams of the Delyndia and
Rabideux series. These soils are on uplands. They are silty
in the uppermost part and sandy in the subsoil and in the
substratum.
Permeability is moderate in the silt loam part of this
soil and moderately rapid in the sandy material. Available
moisture capacity is low to moderate. These soils are very
strongly acid. Fertility is low. Plant roots can penetrate to
a depth of 30 inches. Runoff is slow, and the hazard of
erosion is slight.
Most of the acreage of these soils is wooded, but a few
areas are cleared and are used for crops. The principal
crops are bromegrass, barley, oats, potatoes, and hardy
vegetables.
Organic matter is needed to help keep these soils in
good tilth and to promote efficient use of moisture and
plant nutrients. Returning crop residue to the soil, adding
manure, and including grasses in the cropping sequence
are ways to help maintain the content of organic matter.
MANAGEMENT GROUP 12 (lllw-1)
Only Kalifonsky silt loam is in this group. It is nearly
level, poorly drained, and 15 to 30 inches deep over very
gravelly sand. This soil is on the edges of muskegs and in
depressions.
Permeability i~derate in this soil. The soil is strongly
acid. Fertility is low. Plant roots generally can penetrate
to a depth of about 24 inches. If this soil is not drained,
the wruter table fluctuates between depths of 12 and 40
inches. The soil is nearly saturated during most of the
growing season. Runoff is slow, and the hazard of erosion
is slight.
Kalifonsky silt loam is wooded. If cleared and artificially
drained, it wou}d be suitable for crops. Grasses, small
grains, and hardy vegetables are suited.
MANAGEMENT GROUP 13 (IIIw-2)
Only Wasilla silt loam is in this group. Tlris soil is nearly
level and poorly drained. It is on flood pla;ins and in
depressions.
Permea;bility is moderate in the uppermost part of this
soil and moderately slorw in the subsoil and in the sub-
stratum. This soU is strongly a:cid. Fertility is low. Plant
roots oan penetrate to a depth of about 24 inches. The
water table generally is at a depth of 2 to 4 feet. Runoff
is slow, and erosion is not a hazard.
Wasilla silt loam is covered by natural vegetation. The
areas .generally are wet throughout the growing-season. If
this soil were cleared and artificially drained, It would be
suita;ble for crops and for pasture.
MANAGEMENT GROUP 14 (IVe-1)
In this group are hilly, well-drained silt loams of the
Nancy, Rabideux, and vVhitsol series. These soils are
moderately deep and deep over very graveJrly or sandy
material. They are on uplands. Slopes are short and
irregular.
Permerubility is moderate in the silty part of these soils.
Available moisture capacity is moderate to high. These
soils ~are strongly actl:l to very strongly acid. Fertility is
low. Plant roots can penetrate to a depth of 30 inches.
Runoff is rapid, and the hazard of water erosion is severe.
Most of the acreage of the soils in this group is wooded.
Keeping a •cover obgrass on areas that are cleared helps to
control water erosion.
MAN,.\GEMENT GROUP 15 (IVe-2)
This group consists of hilly, well-drained silt loams od'
t;he Kashwitna nnd Rabideux series. These soils are shallow
to very grwvelly material. They are on uplands and have
short and irregular slopes.
Permea:bility is moderate in the uppermost part of these
soils and rapid in the lower part. A vaila'ble mo~sture capa-
city is low to moderate. These soils ·are strongly acid. Fer-
tility is low. Plant roots can penetrate to ·a depth of 24
inches. Runoff is rapid, and the hazard of water erosion is
severe.
Most of the acreage of these so~ls is wooded, hut .a few
areas are cleared and are used for crops. Keeping a cover
of grass on areas cleared for cultivation helps to contro~
the hazard of ·water erosion.
MANAGEMENT GROUP 16 (IVe-3)
In this group are nearly level to rolling, moderately well
drained ·and well drained silt loams of the Homestead
series. These soils are shaHow to coarse gravelly material.
They are on uplands.
Permeability is moderate in the uppermost 5 to 10 inches
of these soils and rapid in the coarse-textured underlying
matm•ial. Available moisture capacity is low. These soils
are strongly acid to very strongly acid. Fertility is low.
SUSITNA VALLEY AREA, ALASKA 33
Plant roots can penetrate to a depth of 15 inches. Runoff
is slow to medium, and the hazard of erosion is slight to
moderate.
The soils in this group are wooded. If cleared for crops,
they should remain in gra;sses most of the time. These soils
tend to' be droughty. They are shaUow to gTavel and are
not suited to crops that need deep tillage.
MANAGEMENT GROUP 17 (IVe-:4)
In this group are hilly, well drained and excessively
drained silt loams of the Delyndia and Rabideux series.
These soils :formed in a mantle o:f silt loam over deep sand.
They are on uplands and have short irregular slopes.
Permeability is moderate in the silt loam part ·of these
soils .and rapid in the sandy material in the substratum.
Availa:ble moisture capacity is low to moderate. These soils
are very strongly rucid. Fertility is ~O'W. Plant roots can
penetrate to a depth o:f 30 inches. Runoff is rapid, and the
hazard of water erosion is severe.
Most of the acreage of the soils in this group is wooded,
but a :few ·areas have been cleared and are used as cropland.
These soils ·are better suited to grasses than to cultivated
crops. Keeping a protective cover o:f plants on the areas
helps to prevent soil washing.
MANAGEMENT GROUP 18 (IVw-1)
This group consists o:f soils o:f the Killey, Moose River,
Niklason, and Susitna series. These soils are nearly level
and are well drained to somewhat poorly drained. They
formed in medium-textured and coarse-textured sediment
laid down by water. The areas are in a complex irregular
pattern on flood plains. Patches o:f other soils generally
are included with these soils.
Permeability is moderate in these soils. The soils are
strongly acid and very strongly acid. Fertility is low to
moderate. Plant roots can penetrate to a depth o:f about
15 to 30 inches. Some of these soils have a high water table
during most o:f the growing season, and others ·are season-
ally flooded :for short periods. Runoff is slow.
All areas of the soils in this group have a cover of
vegetation. In places the native grasses are suitable :for
limited grazing. If these soils are used :for crops, artificial
drainage or protection :from flooding is needed. These
practices, however, are not feasible on many small areas
o:f included soils. If the soils in this group were cleared
and drained or protected :from flooding, they would be
suited to grasses and small grains grown :for :forage. In
places small areas of included soils that occupy slightly
higher positions in the landscape are suitable :for growing
hardy vegetables.
MANAGEMENT GROUP 19 (IVw-2)
In this group are nearly level, poorly drained soils of
the Coal Creek and Slikok series. These soils :formed in
deep silty material, in shallow depressions, and along
small drainageways. The surface layer is silt loam or
mucky silt loam.
Permeability of these soils is moderate. The water table
is •at a depth of as much as 36 inches. These soils are
strongly acid to very strongly acid, and :fertility is mod-
erately low. Plant roots generally can penetrate to a depth
o:f 20 to 30 inches. Runoff is slow.
The soils in this group are in vegetation. If artificially
drained, they would be suitable :for hardy vegetables and
also :for grasses and small grains grown :for :forage. In
places these soils support native grasses that are suitable
:for limited grazing.
MANAGEMENT GROUP 20 (VIe-1)
This group consists o:f moderately steep, well-drained
silt ·loams of the Kashwitna, Nancy, Rabideux, and 'Whit-
sol series. These soils are underlain by sand or very grav-
elly sand. They are on uplands. Slopes are short and
irregular.
Permeability is moderate in the mantle o:f silt loam, and
available moisture capacity is low to moderate. These soils
are strongly acid to very strongly acid. Fertility is low.
Plant roots can penetrate to a depth o:f 24 to 30 inches.
Runoff is rapid, and the hazard o:f water erosion is very
severe.
Most of the acreage o:f the soils in this group is wooded.
These soils are not suitable :for cultivation, because the
hazard o:f gully erosion is severe on areas that are cleared.
They are well suited to woodland, wildlife habitat, and
recreational activities. If cleared, these soils can be im-
proved :for permanent pasture by preparing a rough seed-
bed, adding :fertilizer, and seeding to adapted perennial
grasses. Topdressing annually with :fertilizer, regulating
grazing, and controlling weeds are practices that help to
keep permanent stands of grass in good condition.
MANAGEMENT GROUP 21 (VIe-2)
In this group are well-drained, hilly and moderately
steep silt loams o:f the Homestead series. These soils are
very shallow to coarse gravelly material. They are on
uplands. Slopes are irregular.
Permeability is moderate in the silty surface layer and
rapid in the very gravelly underlying material. Available
moisture capacity is low. These soils are strongly acid.
Fertility is low. Plant roots can penetrate to a depth of
15 inches. Runoff is rapid, and the hazard o:f water erosion
is severe.
Most of the soils in this group have a cover o:f plants.
They are not suitable :for cultivation and should be left
in permanent vegetation. Cleared areas can be renovated
and seeded to perennial gTasses :for permanent pasture,
but grazing must be carefully regulated to maintain a
good stand of grass. Topdressing annually with :fertilizer
and controlling weeds are also needed.
MANAGEMENT GROUP 22 (VIs-1)
Only Chena fine sandy loam is in this group. This soil
is nearly level, well drained, and shallow to silty and sandy
sediment over sand and gravel. It is on alluvial plains
along the major streams of the survey area.
Permeability is rapid, and available moisture capacity
is low. This soil is medium acid. Fertility is low. Plant roots
can penetrate to a depth o:f 15 inches. Runoff is slow, and
the hazard o:f erosion is slight.
Most of Chena fine sandy loam is wooded. This soil is not
suitable :for cultivation, because o:f shallowness and low
available moisture capaoity. If cleared, areas of this soil
could be renovated and seeded to perennial grasses :for
permanent pasture. Adding :fertilizer, controllino· weeds
d 1 . . b ' an regu atmg gTazmg are practices that help to maintain
satisfactory stands of grass.
34 SOIL SURVEY
MANAGEMENT GROUP 23 (Vlw-1)
Only Tidal marsh is in this group. It consists of nearly
level, poorly drained, clayey tidal sediment on plains
along the edges of Cook Inlet.
Permeability and runoff are very slow. The areas of
Tidal marsh are wet throughout the growing season, and
they are inundated occasionally by exceptionally high tides
or are flooded by overflow from fresh-water streams.
Tidal marsh supports stands of sedges, native grasses,
and aquatic plants. In many places the vegetation is suit-
able for limited grazing. Topdressing with fertilizer and
seeding to adapted perennial grasses are practices that help
to improve the quality and quantity of forage for livestock.
MANAGEMENT GROUP 24 (Vlw-2)
This group consists of nearly level, poorly drained soils
of the Dinglishna and Moose River series. These soils
formed in stratified silty and sandy sediment. They are on
the edges of muskegs and along flood plains of small
streams.
Permeability generally is moderate in most of these soils,
but the cemented layer in the subsoil of the Dinglishna soils
restricts the movement of air and water. The soils are
strongly acid to very strongly acid. Fertility is low. Plant
roots can penetrate to a depth of 12 to 15 inches. Runoff is
very slow. The water table generally is near the surface, but
in years when rainfall is less than normal it recedes rapidly
to a depth of several feet for short periods. Some areas
remain ponded for as much as several weeks.
The acreage of the soils in this group is wooded. In places
native grasses are suitable for limited grazing. The soils in
this group are not suitable for cultivation, but if artifi-
cially drained they could be seeded to adapted grasses,
fertilized, and used for producing permanent forage.
MANAGEMENT GROUP 25 (VIIe-1)
In this group are steep, well-drained silt loams of the
Kashwitna, Nancy, and Rabideux series. These soils are
shallow to moderately deep over very gravelly material.
They are on uplands, and they have irregular slopes.
Permeability is moderate in the mantle of silt loam and
rapid in the gravelly substratum. These soils are strongly
acid to very strongly acid. Fertility is low. Plant roots can
penetrate to a depth of about 24 to 30 inches. Runoff is
rapid, and the hazard of water erosion is very severe.
All areas of the soils in this group are wooded. These
soils are not suitable for crops or for improved pasture.
The areas should be left in vegetation.
MANAGEMENT GROUP 26 (VIIe-2)
Only Bernice sandy loam, steep, is in this group. This
excessively drained soil is very shallow to very gravelly
material. It is on upl·ands.
Permea;bility is rrupid in this soil. The soil is very
strongly acid. Fertility is very low. Plant roots can pene-
trate to a depth of 20 inches. Runoff is rapid, and the
hazard of erosion is very severe.
Bernice sandy loam, steep, is wooded. H is not suitable
for cultiV'ated crops or for improved pasture and should
remain in permanent vegetation.
MANAGEMENT GROUP 27 (VIIw-1)
This group consists of soils of the Clunie and Salamatof
series. These soil81t're in or near the edges of muskegs. The
areas are made up mainly of Clunie and Sa:lamatof peats,
but patches of Delyndia soils in a complex associated with
Salamatof soils occur in a few areas. Clunie and Sa1amatof
peats are nearly level and very poorly drained. Delyndia
soils are nearly level to hilly and somewhat excessiv~ly
drained.
These soils are slightly acid to extremely acid. The
w!llter table in the very poorly drained soils generrully is
at or near the surface, but at times it drops to a depth of
several feet. Plant roots can penetra;te to a depth of about
12 to 20 inches.
The soils in this group •are covered by vegetation that
is suitable for limited grazing in places. These soils are
not suitable for cultivation or for improved pasture.
MANAGEMENT GROUP 28 (VIIw-2)
Only Jacobsen very stony silt loam is in this group. This
soil is nearly leve'l •and poorly drained. It is on the edges
of muskegs and on the flood plains of sma:ll streams.
Permeability is moderate in this soil. The soil is very
strongly ·aoid. Fertility is •low. Plant roots can penetrate
to a depth of a:bout 18 inches. The water table is high, and
the surface generally is wet during most of the growing
season.
Jacobsen very stony silt loam is in vegetation. It is not
suitable for cultiva:tion or for improved pasture. In a few
places the plants are suitable for limited gra:uing.
MANAGEMENT GROUP 29 (Vllw-3)
Only Mixed alluvial land is in this group. It is nearly
level and consists of sandy and gravelly sediment laid
clown by water. The areas are along the edges of rivers and
streams.
Most areas of this soil are flooded frequently, though
the small included tracts are rarely flooded.
Mixed al'luv·ial •land is in natural vegetation. It is not
suitable for cultivation, but in places patches of grasses
are suitable for lirdited grazing.
MANAGEMENT GROUP 30 (Vllle-1)
Only Terrace eJcarpments is in this group. It consists
mainly of silty and sandy material along flood pJ.ains of the
Susitna River. The areas •are steep and narrow and are
made up of active landslides •and gullies that are separated
by alternate strips and patches of stabilized areas.
The stabilized areas generally are wooded or are covered
by brushy vegetation. The active landslides and gullies are
almost barren of vegetation. Terrace escarpments is not
suitable for crops or for pasture. Leaving the areas in vege-
tation helps to control accelerated erosion.
MANAGEMENT GROUP 31 (VIIIs-1)
Only Gravel pits are in this group. The pits are more
than 3 acres in size. They generally are well drained, but a
few •are ponded.
Gravel pits generally are barren, hut sparse stands of
grasses, forbs, shrubs, and tree seedlings grow in places.
The areas have no value for farming.
MANAGEMENT GROUP 32 (VIIIw-1)
This group consists of Gravelly alluvi•alland and Tidal
flats. These land types are nearly level and are on tidal
plains and flood plains along the major streams of the sur-
vey area. The •areas are frequently inundated or flooded
SUSITNA VALLEY AREA, ALASKA 35
and are almost barren of vegetation. They have no value
for farming.
Woodland
.About '72 percent of the acreage of the Susitna Valley
Area is wooded, but only about two-thirds of the woodland
bas afotential for annually producing at least 20 cubic
feet o industrial wood per acre (13). Trees in the Area
that have commercial value are paper birch (Betula pa-
PJLrifera), white spruce (Picea glauca), quaking aspen
(Populus tremuloides), and cottonwood (Populus balsam-
ifera and Populus trichocarpa) (13). Black spruce (Picea
mariana) is ·also common, especially on poorly drained
soils, but the trees generally are small and spindly and
have little or no commercial value.
Woodland groups
The soils in the Susitna Valley Area have been placed
in woodland groups on the basis of soil characteristics that
affect the growth of trees. Each group is made up of soils
that are similar in potential productivity, use suitability,
and management needs, determined by information col-
lected during the preparation of this survey and data
published by Farr (4), Gregory (6), Hutchinson (8), and
the U.S. Forest Service, Institute of Northern Forestry
(23).
In the paragraphs that follow, the woodland groups
recognized in the Susitna Valley Area are described. For
the soils in Groups I, II, and III, table 3 provides data on
site index and growth and yield rates, by wood crops. In
addition, the table gives ratings for the limitations and
hazards of the soils for woodland use. The factors con-
sidered ·are erosion hazard, windthrow hazard, plant com-
petition, and equipment limitations. These factors are dis-
cussed in the paragraphs that follow. Data are not pro-
vided for Groups IV and V in table 3, because the soils in
these groups do not support commercial stands of timber.
Erosion hazard is the degree of potentiaiJ. soil erosion
that is likely to occur following cutting operations or
wher:e soil is exposed along roads, trap.s2 fire lanes, and log,
deckmg areas. Among the character1st1cs of the soH that
affect erosion are slope, ·stability, infiltration, and permea-
bility. The rating .is slight if the hazard of erosion is negli-
gibiJ.e; moderate if special attention and practices are
needed to control erosion; and severe if intensive manage-
ment is needed to control erosion.
W indthrow hazard is the danger of trees being blown
down by wind. It depends on soil characteristics that con-
trol development of tree roots and affect stability. The
mting is slight if ·trees are not expected to be blown down
by commonly occurring winds; moderate if some trees are
expected to blow down during periods of excessive wet-
ness and high winds; and severe if many trees are expected
to blow down during periods of soil wetness and moderate
or high winds.
Plant competition is the invasion or growth of un-
desira:ble kinds of plants on different kinds of soil when
openings are made in the canopy. The rating is slight if
undesirable plants do not hinder growth and estabEsh-
ment of seedlings of desimble kinds of trees; moderate if
undesirable plants hinder, but do not prevent growth and
establishment of desirable tree seedlings; and severe if the
undesirable plants must be reduced to •allow desirable tree-
seedlings to survive and grow.
Equipment limitations are based on soil characteristics
and features of relief that restrict or prevent use of con-
ventiomd equipment for planting and harvesting wood
crops, for constructing roads, and for controlling fires.
The rating is slight if no restrictions exist relative to the
kind of equipment that can be used or to the time of year
that the equipment can be used; moderate if there are
seasonal restrictions of less than 3 months or if other re-
striotions caused by slope, wetness, stones, or other soil
characteristics moderately limit use of equipment; and
severe if a ·period of 3 months or more exist when equip-
ment cannot be used or if there •are other severe restrictions
caused by steep slopes or extreme wetness. This type of
hazard is likely to require both detailed scheduling of
logging and specialized equipment.
GROUP I
In this group are nearly level •to steep, well-drained,
shal1ow to moderately deep soils of the Chulitna, Flat
Horn, Kashwitna, Nancy, Rabideux, •and Whitsol series.
Most of these soils are in the Rabideux-Salamatof, Nancy-
Kashwitna, Nancy-Delyndia, and Kashwitna-Homestead
associations shown on the "General Soil Map" in the back
of this survey. These soils are on terraces and moraines.
Slopes are short and irregular and seldom are more than
300 feet long. Elevation generally is less than &00 feet,
but on a few moraines it is •as much as 1,300 feet.
The soils in this group support about 65 percent of the
trees that have potential commercia;! value in the survey
area. A mixture of paper birch and white spruce is com-
mon, hut quaking aspen grows in a few places. Paper birch
is dominant throughout most of the Area, but the pro-
portionate stocking varies. Both paper birch and aspen
are pioneer trees that characteristically invade burned-
over •areas. White spruce, the climax tree, generally be-
comes estrublished in young stands of paper birch or aspen,
but it generally rema;ins in the understory position for
many years. Both paper birch and aspen are susceptible
to infection and decay. Because of the lrutitude of the Area,
however, aspen tends to remain vigorous longer and to
decay more slowly than stands that grow in other parts of
Alaska. Generally, as stands on the soils in this group reach
90 to 100 years, they begin to deteriorate rapidly, and
white spruce, if present, becomes dominant (12).
Stands that are dominantly pa;per birch or aspen gen-
erally are of even age. These stands range from less than
40 years on recently burned or cutover areas, commonly
near the rai·lroad, to about 120 years in the northern part
of the Area. White spruce is in the understory of most of
the younger stands.
Age and height measurements show that mature paper
birch, 70 to 100 years old, on these soils commonly •attain
a height of 55 to 65 feet. A few stands that are 60 to 70
years of age average 50 to 60 feet in height. The diameter
at breast height for mature paper birch ranges from
about 8 to 14 inches, and the average diameter is rubout 11
inches. Preliminary woodland inventory statistics for the
Susitna Valley Area show that the net volume of paper
birch averages about 965 cubic feet per acre and that the
gross annual growth averages about 20 cubic feet per acre.
These figures, however, include stands of all ages and
densities of stocking. In well-stocked ma;tnre stands thP
,-
36 SOIL SURVEY
TABLE 3.-Woodland suit
[Absence of data indicates that the tree
Site index for-1 Average annual growth for-2
----Woodland group and series
Aspen
I
Birch White Aspen
I
Birch White
spruce spruce
Group I: Shallow to moderately deep, well-drained
Cu. ft./acre Cu. ft./acre Cu. ft./acre
51 52 68 27. 2 27. 1 23.2
soil~ on uplands.
Chulitna, Flat Horn, Kashwitna, Nancy, Rabideux,
Whitsol.
Group II: Very shallow, somewhat excessively drained 53 51 56 32. 7 26. 0 I 15. 6
and excessively drained soils on uplands. I
Bernice, Chena, Delyndia, Homestead.
I
Group III: Shallow to deep, well-drained soils on ----------48 68 ------------22. 6 23. 2 I
alluvial plains.
Niklason, Schrock, Susitna.
1 The height, in feet, of the dominant vegetation taken at or calculated to an index age of 50 years for aspen and birch, and 100 years
for white spruce. Site index data are based on field measurements and on information published by Gregory (6).
2 Growth figures represent the average annual growth increment, in cubic feet per acre, at age 65 for aspen; age 85 for birch; and age
estimated net volume of trees larger than 4.5 inches at
breast height ranges up to 2,800 cubic feet per acre and
annual growth up to 50 cubic feet per acre.
Few mature stands of white spruce are in the Area. Ac-
cording to Lutz (112), white spruce can attl:l!in a height
of 100 feet and a diameter at breast height of more than
20 inches. In general, however, the largest trees in the Area
are 60 to 70 feet in height and 8 to 12 inches in diameter.
Lutz estimates that at the age of 160 years good stands of
white spruce would yield 3,900 cubic feet, or 15,500 board
feet per acre.
The hazard of erosion is severe on these soils if slope is
more than12 percent. In places roads, skid trails, and deep
tracks of heavy equipment made during harvesting collect
and concentrate runoff water from heavy rains or melting
snow, which causes gullies to form rapidly. Minimum dis-
turbance of the surface soil during harvesting helps to
control water erosion. In addition, unprotected areas
should be fertilized and seeded to adapted grasses as soon
as feasible after harvest. The hazards of windthrow, plant
competition, and equipment limitations generally are
moderate on these soils.
Limited use is made of the trees on the soils in this
group, and in many places the paper birch and aspen are
overmature. In a few accessible places, trees are harvested
to provide fuel, and a few white spruce are harvested to
provide logs for houses. In addition, limited quantities of
rough lumber are supplied by small sawmills that operate
from time to time.
GROUP II
In this group are nearly level to steep, somewhat exces-
sively drained and excessively drained, very shallow soils
of the Bernice, Chena, Delyndia, and Homestead series.
These soils are on alluvial plains along major streams of
the survey area and on terraces, outwash plains, and
moraines. Most of these soils are in the Nancy-Kashwitna
and Nancy-Delyttdia associations shown on the "General
Soil Map" in the back of this survey, but many small tracts
occur in other associations. Elevation ranges from 50 to 500
feet.
The soils in this group support about 20 percent of the
trees that have potential commercial value in the survey
area. The stands ov-most of these soils are similar in com-
position and in age to the stands that grow on the soils in
Group I. The Chena soils, however, support a few stands
of cottonwood, and in places quaking aspen is dominant on
the Bernice, Delyndia, and Homestead soils.
The hazard (/f erosion and equipment lim.itations are
severe on the Bernice soils and on scattered hilly to steep
areas of Delyndjp, and Homestead soils. Minimum disturb-
ance of the surface mat of organic material on these soils
during harvesting helps to control erosion. In addition
unprotected and scraped areas should be seeded to grasses
as soon as possible after harvesting. Plant competition is
moderate on these soils.
The average a1mual growth and yield rates are slightly
higher for aspen and slightly lower for birch on these soils
than on the soils in Group I. According to limited field
measurements, however, growth and yield rates of white
spruce are significantly lower on the soils in this group.
A few trees on the soils in this group are harvested to
provide logs and fuel for local use.
GROUP III
This group consists of nearly level, well-drained soils of
the Niklason, Schrock, and Susitna series. These soils are
on alluvial plains along the major streams and rivers of
the survey area. Most of these soils occur in the Susitna-
Schrock association shown on the "General Soil Map" in
the back of this survey.
The soils in this group support about 15 percent of the
trees that have potential commercial value in the survey
area. Cottonwood is dominant on most of these soils. Black
cottonwood (Populus trichocarpa) and balsam poplar
SUSITNA VALLEY AREA, ALASKA 37
ability grouping of the soils
does not generally grow on the soil]
I
Yield for-3 Management hazards and limitations --------
Aspen Birch White Erosion hazard
I
Wind throw Plant Equipment
spruce hazard competition limitations
.:.-----I
cu. ft./acre Cu. ft./acre Cu. ft./acre
1, 768 2, 307 3, 013 Slight if slope is 0 to 3 percent; Moderate _______ Moderate _______ Moderate.
moderate if slope is 3 to 12
percent; severe if slope is
more than 12 percent.
I
2, 124 2, 211 2, 033 Slight if slope is 0 to 3 percent; Moderate _______ Moderate _______ Slight if slope is
moderate if slope is 3 to 12 less than 20 per-
percent; severe if slope is I cent; moderate if
more than 12 percent. slope is 20 percent
and more.
------------1, 923 3, 013 Slight ________________________ Moderate ______ Moderate _______ Moderate.
130 for white spruce, as determined from tables published by Capps (3), and by Gregory (6).
3 Yields represent the volume yield, in cubic feet per acre, from trees more than 4.5 inches in diameter at breast height in well-stocked
stands at age 65 for aspen, 85 for birch, and 130 for white spruce.
(Populus balsamifera) grow in the Area, and both com-
monly are referred to as cottonwood because it is difficult
to distinguish one from the other on most sites. Many of the
cottonwood stands are essentially pure, but white spruce is
common in some of the older stands, and paper birch has
become established in a few stands. Many of the cotton-
wood trees on these soils grow from 80 to 100 feet in height
and to more than 24 inches in diameter. Exceptionally large
trees are 120 to 140 feet in height and 3 to 5 feet in diameter.
. The soils in this group have slight to moderate hazards
or limitations in the growing and harvesting of timber. In
places, however, operations are delayed for short periods
because of occasional flooding. The hazard of windthrow,
plant competition, and equipment limitations on these soils
generally are moderate. In places these factors present
management and harvesting problems, but these generally
can be overcome.
' The average annual growth and yield rates for white
s-pruce are estimated to be equal to those of white spruce
that grow on the soils in Group I. Limited field measure-
ments for paper birch and aspen, however, indicate that
growth and yield rates for these trees are less than for those
on soils in Group I and Group II.
A few trees on the soils in this group are harvested to
provide logs for local use.
GROUP IV
This group consists of nearly level soils of the Caswell,
Coal Creek, Dinglislma, Kalifonsky, Lucile, Moose River,
Slikok, ·and Wasilla series. Caswell soils are well drained,
and Lucile soils are moderately well drained, but the others
are poorly drained. These soils are scattered throughout
most of the survey area.
The soils in this group commonly support stands of
slow-growing black spruce that have no commercial value.
A. few areas, however, are covered by dense stands of alder
and willow.
GROUP V
In this group are nearly level, poorly drained and very
poorly drained soils of the Clunie, Jacobsen, and Salama-
tof series. These soils are in muskegs and on tidal plains.
They occur mainly in the Clunie-Tidal Marsh and
Salamatof -Jacobsen associations shown on the "General
Soil Map" in the back of the survey.
The soils in this group do not support commercial stands
of timber. The vegetation on the soils in muskegs is domi-
nantly sphagnum moss, sedges, ·and low-growing shrubs,
but clumps of black spruce grow in places. The vegetation
on the soils on tidal plains is grasses, sedges, and other
aquatic plants.
Wildlife a
A variety of mammals, birds, and fish frequent the
Susitna Valley Area. Moose are the most important game
animal. They are primarily browsing animals that feed
on young growth of willow, birch, and aspen. In places
moose also eat a few farm crops, and in spring and early
in summer they feed on aquatic plants, grasses, and other
succulent plants. The moose population fluctuates in ac-.
cordance with such factors as availa;bility and quality of
browse, weather conditions, hunting pressure, and popu-
lation density of predators. In summer and early in fall
moose generally migrate to high elevations near timber-
lines on mountain slopes that border the Area. Late in fall
and in winter moose commonly migrate to lower eleva-
tions, where browse is more readily available and snow is
less deep.
Both black bear and brown bear are in the Area. The
diet of these mm1ivorous animals consists of large and
3 Based on information supplied by JAcK C. DIDRICKSON, game
biologist of the Alaslm Department of Fish and Game, and on the
work of RHODES an'd BARKER (14).
38 SOl'L SURVEY
small mammals, fish, insects, and a variety of wild herbs
and berries. Among the important furbearers are beaver,
coyote, fox, lynx, marten, mink, muskrat, otter, weasel,
and wolves. Other animals include porcupine, snowshoe
hare, red squirrel, ground squirrel, shrew, and mice.
The Area is a l so a nesting ground and stopover for a
variety of clucks and geese, sandhill cranes, whistling
swans, and other migratory birds and waterfowl. Spruce
grouse and willow, rock, and whitetail ptarmigan are
the main upland game birds. Other birds are hawks,
eagles, falcons, ravens, and many kinds of songbirds and
shorebirds.
The principal fish are burbot, grayling, salmon, suckers,
trout, and whitefish.
Mosquitoes and many kinds of flies, ants, bees, and other
insects are fairly numerous. They are an important part
of the diet for some of the larger wildlife.
The kinds and ablmdance of wildlife depend largely on
the type and condition of habitat, which, in turn, is related
to the kinds of soil and land use. Some kinds of wildlife
are adapted to woodland, and others to muskegs, brushy
areas, or marshes. A few of the larger animals, moose, for
example, need all of these areas at various times of the year
for food, cover, and calving.
Distribution of wildlife in relation to the soil assoc ia-
tions in the Susitna Valley Area is discussed in the para-
graphs that follow. The associations are described in the
section "General Soil Map," and the soils in each associ·a-
tion are delineated on the map in the back of this survey.
RABIDEUX-SALAMATOF ASSOCIATION.-The contrasting
soils and vegetation in this association are favorable for
wildlife habitat. Consequently, most of the wildlife com-
mon to the Susitna Valley Area, except for those types that
frequent only coastal plains, can be found in this associa-
tion.
Most of the Rabideux soil s, which are dominant in this
association, are wooded. The stands consist of overmature
paper birch that are being gradually replaced by white
spruce. These trees commonly have a d ense lmderstory of
woody shrubs and herbaceous plants that furnish excellent
cover for both l arge and small animals and songbirds.
\iVillo w, paper birch, •and aspen seedlings, however, are not
common in this association. A wide variety of food gen-
erally is available on Rabideux soils for birds and for
animals other than moose.
The cover of vegetation on the Rabideux soils is inter-
rupted by many areas of very poorly drained Salamatof
soils in open muskegs and by soils along streams that sup-
port scattered patches of brush (fig. 5). The vegetation
on Salamatof soils is dominantly sphagmm1 moss, aquatic
plants, and low-growing shrubs. These open wet areas pro-
vide excellent habitat for such birds as terns, snipes, yel-
lowlegs, and sandhill cranes. Small ponds and streams in
some of the muskegs are used by ducks for f ee ding and
nesting. In places moose eat the aquati c plants at night,
and black bear eat the berries that grow in these areas on
Salamatof soils.
The most important habitat in the associ:ation consists
of the many brushy areas along streams and in areas be -
tween open muskegs and wooded soils on uplands. These
areas provide abundant and varied food and cover suitabl e
for many kinds of wildlife in the survey area.
In this association are many small lakes, rivers, and
streams that are used by a v•ariety of migratory waterfow 1,
including ducks, geese, loons, and swans. In summer and
early in fall most of the streams provide valuable spawn-
ing beds for fairly heavy runs of salmon. In addition to the
sal mon, minbow trout, grayling, and Dolly Varden trout
are in m any of the lakes and streams. These waters are also
Figure 5.-Stands of willow brush provide browse for moose on Killey-Moose R iver complex on flood plain of a small stream.
SUSITN A VALLEY AREA, ALASKA 39
used by furbearing animals, especially beaver, mink, and
otter. . . . . NANCY-KASHWITNA ASSOCIATION.-The maJOr SOilS ill
this association support vegetation that is dominantly
paper bi.rch. The stands vary greatly in afSe, but they gen-
erally are much younger thanthe stands ill the Rabideux-
Salamatof association. In general, the understory is not
so dense and does not provide so much cover or so great a
variety of food for wildlife as the understory in older
stands. The quantity and condition of browse for moose
vary, but the total available browse per acre in winter
probably is greater than in other associations in the survey
area. The favorable browse conditions are partly the re-
sult of many forest fires that occurred in this section of
the Area 50 or 60 years ago.
Many small tracts of contrasting soils in this associa-
tion afford suitable habitat for almost all kinds of animals
and birds that frequent the Area. Small lakes, ponds, and
streams are used by waterfowl, furbearers, and all kinds
of fish, including spawning runs of salmon.
NANCY-DELYNDIA ASSOCIATION.-The major soils in this
assoc:Vation support vegetation that is dominantly paper
birch. The understory is fairly dense and provides good
cover for a variety of mammals and birds. Readily avail-
able browse occurs along the Little Susitna River, along
small streams, and between wooded areas and muskegs.
Most kinds of wildlife common to the Area frequent this
association. Moose migrate in and out of the Area, but
because the adjoining open muskegs and Tidal flats are
favorite calving grounds, the number of moose generally is
greatest in spring.
KAsHWITNA-HOMESTEAD ASSOCIATION.-The kinds and
abundance of wildlife habitat in this association are simi-
lar to those in the Niancy-Kashwitna association. Most of
the wildlife common to the Area, except those that fre-
quent only the coastal areas, populate this association. A
few moose use this habitat almost the year around, but the
number of moose is greatest in winter.
SusiTNA-SCHROCK ASSOCIATION.-The soils in this asso-
c:Vation are along the major rivers and streams in the sur-
vey area. The vegetation on the Susitna and Schrock soils
consists mainly of stands of large cottonwoods. The under-
story includes dense patches of alder and willow. Many of
the other soils in the association support dense patches of
young willow that are used by moose for browse in winter.
These,areas are heavily browsed in winter.
Furbearers, especially those that frequent streams, also
concentrate in this 'association. In addition, black bear
and brown bear frequent the river banks in summer and
early in fall to eat salmon. Some of the best pools for sport
fishing in the Area are near the mouth of the small streams
that flow into the Susitna River, where schools of rainbow
trout 'and grayling tend to congregate at various times of
the year.
CLUNIE-TIDAL MARsH ASSOCIATION.-The soils in this
assoc]ation are nearly level and very poorly drained. They
are on broad low-lying areas along Cook Inlet. The vege-
tation, a wide variety of aquatic plants, is used primarily
and heavily by migratory waterfowl,and shorebirds. Iri
spring, however, this is a favorite calving area for moose.
SALAMATOF-JACOBSEN ASSOCIATION.-In this association
are nearly level, very poorly drained peats in large open
muskegs and nearly level, very poorly drained mineral soils
along the edges of muskegs. On the Salamatof peats, which
451-728-73--4
are dominant in this association, the vegetation consists of
sphagnum :r;noss, aquatic plants, and low shrubs. The vege-
tation on the miner:al soils generally consists of stunted
black spruce or of willow and alder brush.
Birds and very small animals_frequent the large open
muskegs. These areas are favorite nesting areas for sand-
hill cranes, terns, snipes, :and similar birds. In addition,
a few ducks use small ponds in the muskegs, and a few
moose feed on the aquatic plants early in summer. Patches
of brush on the edges of muskegs provide an abundance of
browse and other food for large animals. A few small
mammals and birds use the dense stands of black spruce
for habitat, but otherwise these stands generally are
sparsely popul,ated by wildlife.
Recreation
In recent years recreat.ional activities have increased
rapidly in the Susitna Valley Area. This increase is espe-
cially apparent in the northern part of the Area, where a
new highway and secondary roads make many of the lakes
and streams and much of the woodland more readily ac-
cessible for camping and other outdoor activities. In ad-
dition, several State and privately operated campgrounds
offer opportunities for fishing, boating, hunting, and hik-
ing. Winter sports are also popular, and groups are now
traveling many of the trails by snow machines. Dogsled
racing and skiing in the nearby mountains are also favorite
winter sports.
The soils in the Area differ in their suitability for
selected recreational uses. For example, one soil may be
well suited to eampsites or picnic areas, but another may
be poorly suited for such use. In table 4 the soils in the
Area 'are rated according to their limitations for recrea-
tional buildings, campsites for tents and trailers, picnic
grounds and other intensive play areas, and paths and
trails. These ratings are useful mainly as ra guide in select-
ing sites for recreation and in planning recreational
developments. They do not eliminate the need for onsite in-
spection of an area before making a final determination
concerning its suitability for a specific use. The ratings are
based on soil features only and generally do not reflect the
influence of such factors as loeation, esthetic V'alue, present
use, problems of sewage disposal and water supply, access
roads, and kinds and density of vegetation. Most parts
of the survey area are favorable for hunting, fishing, and
similar activities, but these uses are not considered in the
table, because they seldom are confined to a specific site.
The ratings used in ta;ble 4 are slight, moderate, severe,
and very severe. A rating of slight means that the soil is
relatively free of limitations that affect its use for the pur-
pose specified or that limitations can be easily overcome.
A rating of moderate means that limitatrons generally
can be overcome by careful planning, good design, and
good management.
A rating of severe means that ·limitations are difficult
to correct or that the· practices needed generally are not
economically feasible. ·
A rating of very severe means that extreme measures
are needed to overcome limitations and that use of the soil
for the specified purpose is not practical.
In the paragraphs that follow, each recreational use
considered in table 4 is defined.
I
~
40 SOI!L SURVEY
TABLE 4.-Ratings and limitations of the soils for recreational purposes
Map
symbol
BeF
Ca
Ch
CIA
CIB
CIC
Cn
Co
De A
DeB
DeC
DeD
Soil name
Bernice sandy loam,
steep.
Campsites for tents
and trailers
Severe : slopes of
12 to 45
percent.
Caswell silt loam____ Moderate:
seasonal high
water table.
Chena fine sandy
loam.
Chulitna silt loam,
nearly level.
Chulitna silt loam,
undulating.
Chulitna silt loam,
rolling.
Moderate:
subject to
flooding.
Moderate:
slippery or soft
when wet.
Modt-rate:
slippery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Clunie p·aat _________ Very severe:
poorly drained;
high water
table.
Coal Creek silt loam_ Severe:
seasonal high
water tabk
Delyndia silt loam,
nearly level.
Delyndia silt loam,
undulating.
Delyndia silt loam,
rolling.
Delyndia silt loam,
hilly.
Slight: slippery
or soft when
wet.
Slight; slippery
or soft when
wet
Moderate: slopes
of 7 to 12 per-
cent.
Severe: slopes of
12 to 20
percent.
Om Delyndia-Salamatof
On
Dr
complex.
For Delyndia
part see De-
lyndia silt
loam, nearly
level; for
Salamatof
part see
Salamatof
peat.
Dinglishna sandy
loam.
Dinglishna-Moose
River complex.
Sev(lte: high
water table.
Severe: poorly
drained; high
water table.
Recreational
buildings
Severe: slopes of
12 to 45
}J<lrcent.
Moderate:
seasonal high
water table.
Moderate:
subject to
flooding.
Moderate:
fair stability.
Moderate:
fair stability.
Moderate:
slopes of 7 to
12 percent.
Very severe:
poorly drained;
high water
table.
Severe:
seasonal high
water table.
Slight: fine sand
below a depth
of about 11
inches.
Slight: fine sand
below a depth
of about 11
inches.
Moderate: slopes
of 7 to 12 per-
cent.
Severe: slopes of
12 to 20
percent.
Severe : high
water table.
Severe: poorly
drained; high
water table.
Paths and trails
Moderate:
slopes of 12 to
45 percent.
Moderate:
seasonal high
water table.
Slight: subject
to flooding.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Picnic areas
Severe: slopes of
12 to 45
percent.
Moderate:
seasonal high
water table.
Moderate:
subject to
flooding.
Moderate:
slippary or soft
when wet.
Moderate:
slippery or soft
when wet.
Slight ____________ Moderate:
Severe: poorly
drained; high
water table.
Severe:
seasonal high
water table.
Slight: slip~ry
or soft when
wet.
Slight: slijlpery
or soft when
when wet.
f Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20 percent.
Severe: high
water table.
Severe: poorly
drained; high
water table.
slopes of 7 to
12 percent.
Very severe:
poorly drained;
high water
table.
Severe:
seasonal high
water table.
Moderate:
slippery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Moderate: slopes
of 7 to 12 per-
cent
Severe: slopes of
12 to 20
percent.
Severe: high
water table.
Severe: poorly
drained; high
water table.
Play areas
Very severe:
slopes of 12 to
45 percent.
Severe:
seasonal high
water table.
Moderate:
subject to
flooding.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to
7 percent.
Severe: slopes
of 7 to 12
percent.
Very severe:
poorly drained;
high water
tablt).
Severe:
seasonal high
water table.
Slight: slipp.')ry
or soft when
wet.
Severa: slopes of
3 to 7 percent.
Severe: slopes of
7 to 12 percent.
Severe: slopes of
12 to 20
percent.
s.were: high
water tabla.
Severe: poorly
drained; high
water table.
KsB
KsC
KsD
KsE
KsF
Kr
SUSITNA VALLEY AREA, AL.A:SKA
TABLE 4.-Ratings and limitations of the soils for recreational purposes-Continued
Soil name
Flat Horn silt loam,
nearly level.
Flat Horn silt loam,
undulating.
Gravelly alluvial
land.
Campsites for tents
and trailers
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Severe: subject
to flooding.
Gravel pits _________ Severe: gravelly
Homestead silt
loam, nearly level.
Homestead silt
loam, undulating.
Homestead silt
loam, rolling.
Homestead silt
loam, hilly.
Homestead silt
loam, moderately
steep.
Jacobsen very stony
silt loam.
material near
surface.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: high
water table.
Kalifonsky silt loam_ Severe: high
water table.
Kashwitna silt loam,
nearly level.
Kashwitna silt
loam, undulating.
Kashwitna silt
loam, rolling.
Kashwitna silt
loam, hilly.
Kashwitna silt
loam, moderately
steep.
Kashwitna silt
loam, steep.
Killey-Moose
River complex.
Moderate:
slippery or soft
when wet.
Moderate:
slippery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severd: slopes
of 12 to 20
perc~nt.
Severe: slopes
of 20 to 30
percent.
Severe: slopes
of 30 to 45
percent.
Severe: high
water table;
subject to
flooding.
Recreational
buildings
Slight: fine
sand at a
depth of about
9 inches.
Slight: fine sand
at a depth of
about 9 inches.
Very severe:
subject to
flooding.
Very severe:
gravelly ma-
terial near
surface.
Slight: slippery
or soft when
wet.
Slight: hazard
of water
erosion.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: high
water table.
Severe: high
water table.
Paths and trails
Slight: slip-
pery or soft
when wet.
Slight: slip-
pery or soft
when wet.
Moderate: sub-
ject to
flooding.
Moderate:
gravelly ma-
terial near
surface.
Slight: slippery
or soft when
wet.
Slight: slippery
0r soft when
wet.
Slight: slippery
or soft wheh
wet.
Moderate:
slopes of 12 to
20 percent.
Moderate:
slopes of 20 to
30 percent.
Severe: high
water table.
Severe: high
water table.
Slight____________ Slight: slippery
or soft when
wet.
Slight: erosion
hazard slight
to moderate.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe : slopes
of 20 to 30
percent.
Severe: slopes
of 30 to 45
percent.
Severe: high
water table;
subject to
flooding.
Slight: slippery
or soft when
w·at.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20 percent.
Moderate:
slopes of 20 to
30 percent.
Severe: slopes
of 30 to 45
percent.
Sever:"l : high
water table;
subject to
flooding.
Picnic areas
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Sevsre: subject
to flooding.
Severe: gravelly
material near
surface.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 7 to
12 percent.
Sever<J: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: high
water table.
Severe: high
water table.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 7 to
12 percent.
Severe : slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: slopes
of 30 to 45
percent.
Severe: high
water table;
subject to
flooding.
Play areas
Slight: slip-
pery or soft
when wet.
Moderate:
41
slopes of 3 to 7
percent.
Very severe: sub-
ject to flooding.
Seven•: gravelly
material near
surface.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to
7 percent.
Severe: slopes
of 7 to 12
percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: high
water table.
Severe: high
water table.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to
7 percent.
Severe: slopes
of 7 to 12
percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: slopes
of ilO to 45
percent.
Severe: high
water table;
subject to
flooding.
42
Map
symbol
Lu
Me
Mr
NaA
NaB
NaG
NaD
NaE
NaF
NcA
NcB
NeG
NeD
NeE
Nk
RaA
RaB
SOIL SURVEY
TABLE 4.-Ratings and limitations of the soils for recreational purposes-Continued
Soil name Campsites for tents
and trailers
Lucile silt loam _____ Moderate: slip-
pery or soft
when wet.
Mixed alluvial land__ Severe: subject
to flooding.
:&ioose River silt
loam.
Nancy silt loam,
nearly level.
Nancy silt loam,
undulating.
Nancy silt loam,
rolling.
Nancy silt loam,
hilly.
Nancy silt loam,
.moderately steep.
Nancv silt loam,
steep.
Nancy silt loam,
sandy substratum,
nearly level.
Nancy silt loam,
sandy substratum,
undulating.
Nancy silt loam,
sandy substratum,
rolling.
Nancy silt loam,
sandy substratum,
hilly.
Nancy silt loam,
sandy substratum,
moderately steep.
_ Niklason fine sandy
loam.
Rabideux silt loam,
nearly level.
Rabideux silt loam,
undulating.
Severe: high
wat~r table;
subject to
flooding.
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20 per-
cent.
Severe: slopes
of 20 to 30
percent.
Severe: slopes of ;;o to 45
percent.
Moderate: slip-
pery or soft
when wet.
Moderate:
slippery or soft
when wet.
Moderate: slopes
of7to 12
percent.
Severe: slopes of
12 to 20 I·er-
cent.
Severe: slopes
· of 20 to 30 per-
cent.
Slight: subject
to occasional
flooding.
Moderate: slip-
peryorsoft
when wet.
Modarate: slip-
peryorsoft
when wet.
Recreational
buildings
Moderate: sea-
sonal high
water table.
Severe: subject
to flooding.
Severe: high
water table;
subject to
flo<-ding.
Slight: silt
loam over very
gravelly sand.
Slight: hazard of
water erosion
slight to
moderate.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes of
12 to 20 per-
cent.
Severe: slopes of
20 to 30
percent.
Severe: slopes of
30 to 45
percent.
Slight: silt
loam over sand.
Slight: hazard
of water erosion
slight to
moderate.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20 p0r-
cent.
Severe: slopes
of 20 to 30 per-
cent.
Slight: subject
to occasional
flooding.
Slight: silt loam
over very grav-
ellysand.
Slight: hazard
of water erosion
-slight to moder-
ate.
Paths and trails
Slight: slip-
pery or soft
when wt-t.
Moderate: sub-
ject to flooding.
Severe: high
water table;
subject to
flooding.
Slight: slip-
pery or soft
when wet.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
. when wet.
Moderate:
slopes of 12 to
to 20 perc0nt.
Moderate:
slopes of 20 to
30 percent.
Severe: slop as ofir
30 to 45
percent.
Slight: slip-
pery or soft.,.
when wet.
Slight: slip-
pery or soft f
when wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20percent.
Moderate:
slopes of 20 to
30percent.
Slight: subject
to occasional
flooding.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Picnic areas
Moderate: slip-
pery or soft
when wet.
Severe: subject
to flooding.
Severe: high
water table;
subject to
flooding.
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Severe: slopes of
30 to 45
percent.
Moderate:
slippery or soft
when wet.
Moderate:
slippery or soft
when wet.
Moderate:
slopes of 7 to 12
percent.
Moderate:
slopes of 12 to
20percent.
Severe: slopes
of 20 to 30 per-
cent.
Slight: subject
to occasional
flooding.
Moderate: slip-
peryorsoft
wet.
Moderate: slip-
pery or soft
when wet.
Play areas
Moderate: sea-
sonal high
water table.
Severe: subject
to flooding.
Severe: high
water table;
subject to
flooding.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to 7
percent.
Severe: slopes of
7 to 12 percent.
Sevdre: slopes of
12 to 20 percent.
Severe: slopes
of 20 to 30
percent.
Severe: slopes of
30 to 45
percent.
Slight: slippery
or soft when
wet.
Moderate:
sbpes of 3 to 7
percent.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20 percent.
Severe: slopes
of 20 to 30 per-
cent.
Slight: subject
to occasional
flooding.
Slight: slippery
or soft when
wet.
Moderate: slopes
of 3 to 7 percent.
-
SUSITNA VALLEY .ARmlA, ALASKA
TABLE 4.-Ratings and limitations of the soils for recreational purposes-Continued
Soil name Campsites for tents
and trailers
Recreational
buildings
Paths and trails Picnic areas
43
Play areas Map
symbol
____---l------------------·l----------------l-----------------1----------------l----------------l-----------------
RaG
RaD
RaE
RaF
RbA
RbB
RbC
RbD
RbE
RdA
RdB
RdC
RdD
RdE
Sa
ShA
Sm
Ss
Rabideux silt loam,
rolling.
Rabideux silt loam,
hilly.
Rabideux silt loam,
moderately steep.
Rabideux silt loam,
steep.
Rabideux silt loam,
shallow, nearly
level.
Rabideux silt loam,
shallow, undu-
lating.
Rabideux silt loam,
shallow, rolling.
Rabideux silt loam,
shallow, hilly.
Rabideux silt loam,
shallow, moder-
ately steep.
Rabideux silt loam,
sandy substratum,
nearly level.
Rabideux silt loam,
sandy substratum,
undulating.
Rabideux silt loam,
sandy substratum,
rolling.
Rabideux silt loam,
sandy substratum,
hilly.
Rabideux silt loam,
sandy substratum,
moderately steep.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20 percent.
Severe: slopes
of 20 to 30 per-
cent.
Severe: slopes of
30 to 45 percent.
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
peryorsoft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slop"es
of 20 to 30
percent.
Moderate:
slippery and
soft when wet.
Moderate:
slippery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Salamatof peat ______ Very severe:
Schrock silt loam,
nearly level.
Slikok mucky silt
loam.
high water
table.
Moderate:
slippery or soft
when wet.
Severe: high
water table.
Moderate: slopes
of 7 to 12 per-
cent.
Severe: slopes of
12 to 20 percent.
Severe: slopes of
20 to 30 percent.
Severe: slopes of
30 to 45 percent.
Slight: siltloam
over very grav-
ellysand.
Slight: hazardof
erosion slight to
moderate.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe : slopes
of 20 to 30
percent.
Slight: silt loam
over sand.
Slight: hazard
of erosion
slight to
moderate.
Moderate:
slopes of 7 to
12 percent.
Severe : slopeo:
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Very severe:
high water
table.
Slight: silt loam
over stratified
fine sand and
very fine sand.
Severe: high
water table.
Susitna fine sandy
loam.
Slight ____________ Slight: fine
451-728--73--5
sandy loam
over stratified
fine sand and
very fine sand.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20percent.
Moderate:
slopes of 20 to
30percent.
Severe: slopes of
30 to 45 percent.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20 percent.
Moderate:
slopes of 20 to
30 percent.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20 percent.
Moderate:
slopes of 20 to
30 percent.
Severe: high
water table.
Slight: slippery
or soft when
wet.
Severe: high
water table.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20 percent.
Severe: slopes
of20to 30
percent.
Severe: slopes of
30 to 45 percent.
Slight: slippery
or soft when
wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Moderate:
slippery or soft
when wet.
Moderate:
slippery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Very severe:
high water
table.
Moderate:
slippery or soft
when wet.
Severe: high
water table.
Severe: slopes of
7 to 12 percent.
Severe: slopes of
12 to 20 percent.
Severe: slopes of
20 to 30 percent.
Severe: slopes of
30 to 45 percent.
Slight: slippery
or soft when
wet.
Moderate: slopes
of 3 to 7 percent.
Severe: slopes
of 7 to 12
percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to
7 percent.
Severe: Es:iopes
of 7 to 12
percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes
of 20 to 30
percent.
Very severe:
high water
table.
Slight: slippery
or soft when
wet.
Severe: high
water table.
Slight____________ Slight____________ Slight.
44 SOIL SURVEY
TABLE 4-Ra.tings and limitations of the soils for recreational purposes-Contmued
Map
symbol
Sw
Te
Tf
Tm
Wa
WhA
WhB
WhC
WhO
WhE
Soil name
Susitna and Nikla~
son fine sandy
loams, overflow.
Campsites for tents
and trailers
Severe: subject
to flooding in
places.
Terrace escarpments_ Severe: very
steep.
Tidal fiats __________ Very severe:
subject to
flooding.
Tidal marsh________ Severe: high
water table;
subject to
flooding.
Wasilla silt loam _____ Severe: high
Whitsol silt loam,
nearly level.
Whitsol silt loam,
undulating.
Whitsol silt loam,
rolling.
Whitsol silt loam,
hilly.
Whitsol silt loam,
moderately steep.
water table;
subject to
flooding.
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
Severe: slopes of
20 to 30
percent.
Recreational
buildings
Severe: subject
to flooding in
places.
Severe : very
steep.
Very severe :
subject to
flooding.
Severe : high
water table;
subject to
flooding.
Severe: high
water table;
subject to
flooding.
Moderate: fair
stability.
Moderate: fair
stability.
Moderate:
slopes of 7 to 12
percent.
Severe: slopes of
12 to 20
percent.
Severe: slopes of
20 to 30
percent.
Paths and trails
Moderate: sub-
ject to flood-
ing in places.
Severe: very
steep.
Severe: subject
to flooding.
Severe : high
water table;
subject to
flooding.
Severe : high
water table;
subject to
flooding.
Slight: slippery
or soft when
wet.
Slight : slip-
pery or soft
when wet.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 12 to
20 percent. •
Moderate: slopes
of 20 to 30
percent.
Picnic areas
Severe: subject
to flooding in
places.
Severe: very
steep.
Very severe :
subject to
flooding.
Severe: high
water table;
subject to
flooding.
Severe: high
water table;
subject to
flooding.
Moderate: slip-
pery or soft
when wet.
Moderate: slip-
pery or soft
when wet.
Moderate:
slopes of 7 to
12 percent.
Severe: slopes
of 12 to 20
percent.
SE-vere: slopes of
20 to 30
percent.
Play areas
Severe: subject
to flooding in
places.
Severe : very
steep.
Very severe :
subject to
flooding.
Severe : high
water table;
subject to
flooding.
Severe: high
water table;
subject to
flooding.
Slight: slippery
or soft when
wet.
Moderate:
slopes of 3 to 7
percent.
Severe: slopes of
7 to 12 percent.
Severe: slopes of
12 to 20
percent.
Severe: slopes of
20 to 30
percent.
Campsites fo1' tents and tmile1'8 are areas suitable for
tents, small trailers, camper units, and the activities that
accompany outdoor Hving. Except for shaping and level-
ing areas for tents and parking, little site preparation is
needed. The soil must be able to support heavy traffic by
people, vehicles, and horses.
Engineering Uses of the Soils
ReC1'eational buildings ( withO'Ut septrc tanks) are suit-
able for seasonal or year-round cabins, picnic shelters,
service buildings, washrooms, and bathrooms.
Picnic aTeas are used for pleasure outings at which a
meal can be prepared. Little preparation of the site is re-
quired, ·other than clearing areas of brush and providing
fireplaces and picnic tables.
Play aTeas are used for various forms of play and for
such organized games as baseball, badminton, and volley-
ball. IntenSive foot traffic is involved, and a nearly level
surface that is firm and well drained generally is needed.
An important consideration is whether a good cover of
plants can be established and maintained on the site.
Some soil properties are of special interest to engineers
because they affect the ·construction and maintenance of
roads, airports, and piJ?elines; the roundations of build-
ings; facilities for stoTlllg water; structures for control-
ling erosion; drainage systems; and systems for disposing
of sewage. Among the properties most important to the
engineer are shear strength, compact~on characteristics,
soil drainage, permeability, shrink-swell characteristics,
grain size, plasticity, and reaction. Also important are
depth to seasonal high water table, flooding hazard, and
relief. Such information is available in this section. Engi-
neers can use it to--
1. Make studies that will aid in selecting and devel-
oping sites for industries, businesses, residences,
and recreational areas.
2. Make estimates of the engineering properties of
soils for use in the planning of systems for dra'in-
SUSITNA VALLEY AREA, ALASKA 45
ing cropland and pasture, grassed w,aterways,
farm ponds, irrigatiOn systems, terraces and di-
versions, and other structures for conseTving soil
and water.
3. Make preliminary evaluations of soil conditions
that will aid in selecting locations for highways,
airports, pipelines, cables, and sewage disposal
fields and in planning more detailed surveys of
the soils at the selected locations.
4. Locate rprobwble sources of sand, gravel, and other
materials for use in construction.
5. Correlate the perrormance Oif engineering struc-
tures with the soi'l mapping units to develop in-
formation for general planmng that will be useful
in designing and maintaining new ·structures.
6. Determine the suitability of the soils ·for cross-
country movement of vehicles and of construction
equipment.
7. Sup)?lement information obtained from other
published maps, reports, and aerial photographs
for the purpose 'Of making ma;ps and reports that
oan be readily used by engineers.
8. Develop other preliminary estimates for construc-
tion. purposes pertinent to the particular area.
Used with the soil map to identify the soi'ls, the engi-
neering interpretations in this section .are useful for many
purposes. ~t should be empha_sized, however, th~t these
interpretat:~:ons are not a substitute ·for the samplmg and
testing needed at a site chosen for a specific engineering
work that involves heavy loads or at a site where excava-
tions are to be deeper than the depths of the layers here
reported. Nevertheless, by using this survey, an engineer
can select and ·concentrate on those soirs most important
for his proposed kind of construction, and in this manner
reduce the number of soil samples taken for laboratory
testing and complete an adequate soil investigation at
minimum cost.
The soil mapping units shOIWil on the maps in this sur-
vey may include small areas of a different soil material.
These included soils may be as much as 2 ·acres in size.
They are too small to be mapped separately and generally
are not significant to the farming in the area, but they may
be important in engineering planning.
Information of value in ·planning engineering work is
given throughout the text, particularly in the sections
"Descriptions of the So'ils" and "Formation and Classi'fi-
cation of Soils."
Some of the terms used in this publication have a specia;l
meaning to soil scientists and a different meaning to engi-
neers. The Glossary defines many such terms as they are
used in soil science.
Much of the 'information in this section is given in tables.
Table 5 gives engineering test data, ta;ble 6 gives engineer-
ing properties of the soils, and table 7 gives engineering
interpretations of the soils.
Engineering classification systems
Soil scientists of the United States Department of Agri-
culture (USDA) classify soils according to texture (920).
In some ways this system of naming textural classes is
comparable to the systems most commonly used by engi-
neers for classifying soils; that is, the system of the
American Association of State Highway Officials
(AASHO) (1) and the Unified system developed by the
U.S. Department of Defense (9292).
Most highway engineers classify soil material in accord-
ance with the AASHO system. In this system soil mate-
rials are classified in seven principal groups. The groups
range from A-1 (gravelly soils having high bearing capac-
ity, the best soils for subgrade) to A-7 (clayey soils having
low strength when wet, the poorest soils for subgrade). If
the soil material is near a classification boundary, it is
given a symbol showing both classes; for example, A-2 or
A---4. Highly organic soils, such as peat and muck, are not
included in the AASHO classification, because their use as
construction material is not practical.
Within each group, the relative engineering value of the
soil material is indicated by a group index number. These
numbers range from 0 for the best material to 20 for the
poorest. The group index number for the tested soils of
the Susitna Valley Area is shown in parentheses following
the soil group symbol in table 5.
Some engineers prefer to use the Unified Soil Classifica-
tion System (9292). In this system soil materials are identi-
fied as coarse grained (eight classes) , fine grained (six
classes), or highly organic. An approximate classification
of soils by this system can be made in the field.
Engineering test data
Table 5 gives test data for samples obtained from four
soil series that are extensive in the Susitna Valley Area.
Selected layers were tested by standard procedures in the
Roads Materials Laboratory of the Alaska Department of
Highways. The samples were chosen to represent the range
in properties in the soils of each series. If more than one
profile was sampled, one represents the modal, or typical,
soil of the series. The other profiles, though within the
range permitted in the series, differ from the modal in
texture, consistence, or some other property that is signifi-
cant in engineering. The results of the tests can be used as a
guide in estimating the engineering properties of the soils
m the survey area. Tests were made for moisture density
relationships, grain-size distribution, liquid limit, and
plasticity index.
In the moisture density tests, a sample of the soil mate-
rial is compacted several times with a constant compactive
effort, each time at a successively higher moisture content.
The moisture content is increased until the optimum mois-
ture content is reached. After that, the density decreases
with increase in moisture content. The highest density
obtained in the compaction test is termed "maximum dry
density." Moisture-density data are important in planning
earthwork because generally the soil is more stable if it is
compacted to about its maximum dry density when it is
at about the optimum moisture content.
Mechanical analyses were made to determine the per-
centages of clay and coarser material in the soils. The
analyses were done by the combined sieve and hydrometer
methods. The percentage of clay determined by the
hydrometer method should not be used as a basis for
naming textural classes of soils.
46 SO:UL SURVEY
TABLE 5.-Engineer
[Tests performed by the Alaska Department of Highways, Road Materials Laboratory, in cooperation with the U.S. Department of
way Officials (AASHO) (1). Absence of an entry indicates
Moisture density data 1 Mechanical analysis 2
Soil name and location Parent material
Depth Percentage passing sieve
from Maximum
surface dry den-Optimum
sity moisture
3 in. 2 in. 1)>~ in. 1 in. %in. %in.
---------------
Inches Lb./cu. ft. Percent
Moose River silt loam: Layered silty and 0-6 75 31 ------ ------ ------ ------ ------------NEXSWX sec. 7, T. 21 N., fine sandy sedi-6-50 99 17 ------------ ------------------ ------R.4W. ment laid down
(Modal) by water.
SWXNEX sec. 24, T. 20 N., Layered silty and 4-32 102 16 ------ ------
100 98 98 98
R.5W. fine sandy sedi-32-50 130 6 100 97 86 74 65 49
(Coarser substratum ment laid down
than modal) by water.
SEXNW)>~sec. 25, T. 26 N., Layered silty and 0-8 103 18 ------ ------ ------ ------ ------ ------
R.5W. fine sandy sedi-8-36 82 30 ------ ------
------ ------------------(Finer texture than ment laid down
modal) by water.
Nancy silt loam: Silt loam underlain 3;l1-9 73 35 _____ .. ------ ------ ------ ------ ------
NWXNWX sec. 20, T. 23 by very gravelly 16-24 90 26 ------ ------
100 97 97 93
N., R.4W. sand. 24-40 126 10 ------100 92 84 80 72
(Modal)
SWXSWX sec. 8, T. 23 N., Silt loam underlain 3-5 71 39 ------ ------ ------------------ ------
R.4W. by very gravelly lG-18 89 26 ------------------ ------
100 99
(Shallower to gravelly sand. 18-50 132 6 93 82 74 64 51 43
material than modal)
NWXSWX sec. 30, T. 20 Silt loam underlain 3;l1-772 90 26 ------ ------ ------------------ ------
N.,R.4W. by sand. 16-28 106 16 ------------ ------ ------ ------ ------
(Sandy substratum) 28-45 104 15 ------------------ ------------100
' Rabideux silt loam:
SWXSWX sec. 20, T. 26 N., Silt loam underlain 2~-5 66 44 ------ ------ ------------ ------ ------
R.4W. by very gravelly 16Yr23 84 31 ------------ ------------------------
(Modal) sand. 23-48 135 6J5 100 90 82 68 61 46
SE)>{SEX sec. 31, T. 26 N., Silt loam underlain 1%-4 71 41 ------ ------------ ------------------
R.4W. by very gravelly 10-15 78 35 ------100 99 98 97 96
(Shallower to sand. 15-32 121 10 95 91 87 79 73 62
gravelly material
than modal)
NEXNEX sec. 30, T. 26 N., Silt loam underlain 4-12 69 42 ------------------------------ ------
R.6W. by glacial till. 13%-20 86 28 ------ ------
100 98 96 94
(Finer substratum 20-40 126 10 100 94 92 87 84 77
than modal)
See footnotes at end of table.
SUSITN A VALLEY ARIEA, ALASKA 47
ng test data
commerce, Bureau of Public Roads (BPR), in accordance with standard procedures of the American Association of State High-
no determination was made or information doe;; not apply]
Mechanical analysis 2-Continued Classification -
Percentage passing sieve-Continued Percentage smaller than-
Liquid Plasticity
limit index AASHO Unified 3
No.4 No. 10 No. 40 No. 200 0.05 0.02 0.005 0.002
(4.7 (2.0 (0.42 (0.074 mm. mm. mm. mm.
mm.) mm.) mm.) mm.)
Percent
---------100 97 58 48 26 4 2 4 NV 5 NP A-4(2) ML
---------100 98 32 21 12 5 4 NV NP A-2-4 SM
97 97 94 42 28 12 3 1 NV NP A-4(1) SM
40 33 20 6 4 2 1 0 NV NP A-1-a(O) GW
---------100 98 43 27 11 5 5 NV NP A-4(2) SM
---------100 98 83 61 50 19 10 41 NP A-5(8) ML
-------------------100 73 61 41 9 4 NV NP A-4(8) ML
92 91 87 77 57 41 8 5 NV NP A-4(8) ML
66 57 45 19 18 11 5 3 NV NP A-1-b(O) SM
---------100 99 76 66 43 9 3 NV NP A-4(8) ML
99 99 96 91 65 35 5 1 33 NP A-4(8) ML
33 25 14 3 3 2 1 1 NV NP A-1-a(O) GW
---------100 97 63 56 41 10 5 NV NP A-4(6) ML
---------100 97 71 62 44 14 8 NV NP A-4(7) ML
99 98 84 9 7 6 5 4 NV NP A-3(0) SP-SM
-------------------100 68 62 36 8 2 NV NP A-4(7) ML
---------100 98 88 78 41 9 3 NV NP A-4(8) ML
37 29 13 2 2 2 1 1 NV NP A-1-a(O) GP
---------100 99 71 61 32 2 0 NV NP A-4(7) ML
96 96 91 70 62 38 7 1 NV NP A-4(7) ML
52 46 23 3 3 2 1 1 NV NP A-1-a(O) GP
100 99 98 75 64 37 5 1 NV NP A-4(8) ML
92 88 86 71 60 30 8 5 NV NP A-4(7) ML
69 61 46 27 21 12 3 1 NV NP A-2-4(0) SM
48 SOIL SURVEY
TABLE 5.--Engineering
Moisture density data 1 Mechanical analysis 2
Depth Percentage passing sieve
Soil name and location Parent material from Maximum
surface dry den-Optimum
sity moisture
3 in. 2 in. 1~~ in. 1 in. %in. %in.
---------------
Inches Lb./cu. ft. Percent
Susitna silt loam:
SE~~SE)4 sec. 28, T. 26 N., Layered silty and 0-5 95 20 ------------------ ------------------
R. 5 w. very fine sandy 5-46 99 19 ------------------------------------
(Modal) sediment laid
down by water.
SW)4NE)4 sec. 35, T. 26 N., Layered silt and 0-8 103 16 ------------------------ ------------
R.5W. very fine sandy 8-36 100 18 ------ ------------ ------ ------------
(Coarser surface layer sediment laid
than modal) down by water.
SW~~SW)4 sec. 10, T. 24 N., Layered silty and 0-4 93 21 ------ ------------ ------ ------------
R. 5 w. very fine sandy 4-38 96 20 ------ ------------ ------ ------------
(Coarser texture than sediment laid
modal) down by water.
1 Based on AASHO Designation T180-57, Method D, Note 2 (1).
2 Mechanical analysis according to AASHO Designation T88-57 (1). Results by this procedure may differ somewhat from the results
that would have been obtained by the soil survey procedure of the Soil Conservation Service (SCS). In the AASHO procedure, the fine
material is analyzed by the hydrometer method, and the various grain-size fractions are calculated on the basis of all the material, in-
cluding that coarser than 2 millimeters in diameter. In the SCS soil survey procedure, the fine material is analyzed by the pipette method,
and the material coarser than 2 millimeters in diameter is excluded from the calculations of grain-size fractions. The mechanical analyses
used in this table are not suitable for use in naming textural classes for soils.
•
TABLE 6.-Estimated engineering
[An asterisk in the first column indicates that at least one mapping unit in this series is made up of two or more kinds of soils. The soils
tions for referring to other series that appear in the first column
Soil series, land types, and map symbols
Bernice: Be F ___________________________________ _
Caswell: Ca ____________________________________ _
Chena:2 Ch ____________________________________ _
Chulitna: Cl A, Cl B, CIC __________________________ _
Clunie:2 Cn ____________________________________ _
Coal Creek: Co _________________________________ _
*Delyndia: DeA, DeB, DeC, DeD, Dm ______________ _
For properties of Salamatof soils in mapping unit
Dm, refertli-Salamatof Eeries.
See footnotes at end of table.
Depth to
seasonal
high water
table
Ft.
(1)
2-4
0-2
1-4
Classification
Depth from l----::c-------------------1
surface of f
typical
profile
In.
0-9
9-30
0-32
32-40
0-6
6-11
11-40
0-37
37-44
0-37
Dominant USDA texture
Sandy loam __________________________________ _
Very gravelly coarse sand ______________________ _
Stratified silt and sand _________________________ _
Very gravelly sand ____________________________ _
Fine sandy loam _____________________________ -
Loamy sand _________________________________ _
Very gravelly sand ____________________________ _
Silt loam _____________________________________ _
Very gravelly sand ___________________________ _
Peat ________________________________________ _
37-50 Silty clay loam _______________________________ _
0-45 Silt loam ____________________________________ _
0-11
11-17
17-40
Silt loam ________________________ -___________ -
Loamy fine sand _____________________________ _
Fine sand ___________________________________ _
SUSITNA VALLEY ARiEA, ALASKA 49
test data-Continued
Mechanical analysis 2-Continued Classification
Percentage passing sieve-Continued Percentage smaller than-
Liquid Plasticity
limit index AASHO Unified a
No.4 No. 10 No. 40 No. 200 0.05 0.02 0.005 0.002
(4.7 (2.0 (0.42 (0.074 mm. mm. mm. mm.
mm.) mm.) mm.) mm.)
Percent
---------100 100 83 58 18 5 3 NV NP A-4(8) ML
-------------------100 61 42 16 7 6 NV NP A-4(5) ML
-------------------100 27 15 9 4 4 NV NP A-2-4(0) SM
-------------------100 59 42 17 7 5 NV NP A-4(5) ML
---------100 99 70 44 17 0 0 NV NP A-4(7) ML
---------100 99 66 43 18 4 2 NV NP A-4(6) ML
3 SCS and BPR have agreed to consider that all soils having plasticity indexes within 2 points from A-line are to be given a border-
line classification. An example of a borderline classification so obtained is SP-SM.
4 No value.
5 Non plastic.
properties of the soils
in such mapping units may have different properties and limitations, and for this reason it is necessary to follow carefully the instruc-
of this table. Absence of data indicates that no estimate was made]
Classification-Continued Percentage passing sieve-
Available
Permea-water Reaction Shrink-swell
No.4 No. 10 No. 40 No. 200 bility capacity potential
Unified AASHO (4.7 (2.0 (0.42 (0.074
mm.) mm.) mm.) mm.)
SM
ln./hr. ln./in. of soil pH value
A-4, A-2 100 95-100 60-70 30-40 2. OQ-6. 30 0. 15-0. 20 4. 5-5. 0 Low.
GW or GP A-1 40-50 30-40 20-30 0-5 6. 30-20. 0 0. 03-0. 05 4. 5-5. 0 Low.
SM or ML A-4 95-100 95-100 70-85 40-55 0. 63-2. 00 0. 20-0. 25 4. 5-5.5 Low.
GM-GP A-1 40-50 30-40 20-30 5-15 6. 3-20. 0 0. 03-0. 05 4. 5-5. 5 Low.
ML or SM A-4 100 100 70-85 40-55 2. 00-6. 30 0. 25-0. 30 5. 6-6. 0 Low.
SM A-2 100 95-100 50-75 15-30 2. 00-6. 30 0. 10-0. 15 5. 6-6. 0 Low.
-GW, GP or
GM-GP
A-1 40-50 30-40 20-30 0-15 6. 30-20. 0 0. 03-0. 05 5. 6-6. 0 Low.
ML A-4 100 100 90-100 70-90 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
GWor GM-A-1 40-50 30-40 20-30 0-15 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
GW
Pt ------------------------------------------ ----------------------------------5. 6-7. 3 High shrink;
low swell.
CL A-7 100 100 100 85-95 0. 06-0. 20 0. 28-0. 32 6. 1-7. 3 Moderate.
ML A-4 100 100 90-100 70-90 0. 63-2. 00 0. 25-0. 30 5. 1-5. 5 Low.
ML A-4 100 100 90-100 70-90 0. 63-2. 00 0. 25-0. 30 4. 5-5. 0 Low.
SM A-2, A-4 100 100 70-80 30-40 0. 63-20. 0 0. 10-0. 15 5. 1-5. 5 Low.
SM A-2 100 95-100 65-80 20-35 ·------------. 0.05-0.07 5. 1-5. 5 Low.
50
Soil series, land types, and map symbols
*Dinglishna: Dn, Dr _____________________________ _
For properties of Moose River soils in mapping
unit Dr, refer to Moose River series.
Flat Horn: FhA, Fh B ________ --------------------
Gravelly alluvial land: Ga _____ ·-------------------
Gravel pits: Gv.
No valid estimates can be made.
Homestead: HoA, HoB, HoC, HoD, HoE ___________ _
Jacobsen: Ja ___________________________________ _
!Califonsky: Ka _________________________________ _
!Cashwitna: KsA, KsB, KsC, KsD, KsE, KsF ______ _
*!Cilley: K r ____________________________________ _
For properties of Moose River soils in this map-
ping unit refer to the Moose River series.
Lucile: Lu ______________ ---______ -__ --_-_______ _
Mixed alluvial land: Me.
No valid estimates can be made.
Moose River: M r _______________________________ _
Nancy:
NaA, NaB, NaG, NaD, NaE, NaF _____________ _
NcA, NcB, NeG, NeD, NeE ___________________ _
Niklason: 2 N k __________________________________ _
Rabideux:
RaA, RaB, RaG, RaD, RaE, RaF _______________ _
RbA, RbB, RbC, RbD, RbE ____________________ _
RdA, RdB, RdC, RdD, RdE ____________________ _
Salamatof: Sa __________________________________ _
Schrock: Sh A_·-________________________________ _
Slikok: Sm _____________________________________ _
See footnotes ati!Jrd..of table.
SOIL SURVEY
Depth to
seasonal
high water
table
Ft.
0-2
2 0-3
0-2
7~-37~
2-3
2 0-2
(1)
(1)
(1)
(1)
(1)
(1)
0-1
(1)
0-2
TABLE 6.-Estimated engineering
Classification
Depth from l---------------------------------1 surface of
typical
profile
In.
0-14
14-20
Dominant USDA texture
Sandy loam and loamy sand ___________________ _
Sand (strongly cemented) _____________________ _
0-9 Silt loam ____________________________________ _
9-40 Fine sand, very fine sand, silt loam (stratified) ___ _
0-7
7-28
0-27
0-22
22-4.0
0-14
14-20
20-30
Very gravelly and cobbly sand _________________ _
Silt loam ____________________________________ _
Very gravelly sand ____________________________ _
Very stony silt loam __________________________ _
Silt loam ________________________________ --__ _
Very gravelly sand ____________________________ _
Silt loam ____________________________________ _
Gravelly sandy loam __________________________ _
Very gravelly sand ____________________________ _
0-10 Silt loam ____________________________________ _
10-36 Fine sandy loam and fine sand ________________ _
36-44 Graveijy and very gravelly coarse sand __________ _
0-16 Silt loam ____________________________________ _
16-30 Very gravelly sand ____________________________ _
0-42 Silt loam, stratified fine sand and silt ___________ _
f
0-24 Silt loam ____________________________________ _
24-40 Very gravelly sand ____________________________ _
0-28 Silt loam ____________________________________ _
28-40 Sand ________________________________________ _
0-17
17-40
Silt loam and loamy fine sand (stratified) ______ _
Very gravelly sand ____________________________ _
0-23 Silt loam ____________________________________ _
23-48 Very gravelly sand ____________________________ _
0-15 Silt loam ____________________________________ _
15-32 Very gravelly sand ___________________________ _
0-20 Silt loam ____________________________________ _
20-40 Sand ________________________________________ _
0-60 Peat ________________________________________ _
0-18 Silt loam __________________________________ _
18-42 Stratified fine sand and silt loam ________ _
0-50 Silt loam ____________________________________ _
SUSITNA VALLEY AREA, ALASKA 51
properties of the soils-Continued
Classifica.tion-Continued Percentage pas~ing sieve-
Available -Permea-water Reaction Shrink-swell
No.4 No. 10 No. 40 No. 200 bility capacity potential
Unified AASHO (4.7 (2.0 (0.42 (0.074
mm.) mm.) mm.) mm.)
ln./hr. ln./in. of soil pH value
SM A-2, A-4 100 100 60-70 30-40 2. 00-6. 30 0. 15-0. 20 4. 5-5. 0 Low.
------------------------------------------------------------------<O. 06 ------------4.5-5. 0 Low.
ML A-4 100 100 85-95 75-85 0. 63-2. 00 0.25-0.30 4. 5-5. 5 Low.
SM A-4 100 95-100 80-90 40-50 0. 63-2. 00 0. 20-0. 25 5. 1-5. 5 Low.
GW or GP A-1 30-50 20-40 15-30 0-5 6. 30-20. 0 0. 30-0. 05 ----------Low.
ML A-4 95-100 90-100 80-90 70-80 0. 63-2. 00 0.25-0.30 4. 5-5. 5 Low.
GWor GM A-1 40-50 20-40 15-30 0-15 6. 30-20. 0 0.03-0.05 5. 1-5. 5 Low.
ML A-4 25-55 20-50 20-30 15-25 0. 63-2. 00 0. 06-0. 08 4. 5-5. 0 Low.
ML A-4 90-100 90-100 85-95 75-85 0. 63-2. 00 0. 25-0. 30 5. 1-5. 5 Low.
GWor GM A-1 40-50 30-40 20 30 0-15 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
ML A-4 100 100 90-100 75-90 0. 63-2. 00 0. 25-0. 30 4. 5-5. 0 Low.
SM A-1 60-70 50-60 40-50 15-25 2. 00-6. 30 0. 10-0. 15 4-5-5. 5 Low.
GW or GP A-1 40-50 30-40 20-30 0-5 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
ML A-4 100 100 90-100 70-80 0. 63-2. 00 0. 25-0. 30 4. 5-5. 0 Low.
SM A-4 100 90-100 75-85 40-50 0. 63-2. 00 0. 20-0. 25 4. 5-5. 0 Low.
GWor GM A-1 60-70 50-60 15-25 0-15 6. 30-20. 0 0. 03-0. 05 4. 5-5. 0 Low.
ML A-4 100 100 90-100 70-80 0. 63-2. 00 0. 25-0. 30 4. 5-5. 0 Low.
GW or GP A-1 40-50 30-40 20-30 0-5 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
SM A-4 95-100 85-95 70-80 35-50 0. 63-2. 00 0. 20-0. 25 5. 1-5. 5 Low.
ML A-4 100 100 95-100 70-80 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
GW,GM, A-1 30-65 25-60 10-45 0-20 6. 30-20. 0 0. 03-20 . .'i 5. 1-5. 5 Low.
GP-GM
ML A-4 100 100 95-100 65-75 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
SM-SP A-3 95-100 95-100 80-90 5-10 6. 30-20. 0 0. 04-0. 06 5. 1-5. 5 Low.
SM or ML A-1 100 95-100 80-90 40-60 0. 63-2. 00 0. 20-0. 25 5. 1-5. 5 Low.
GW or GP A-1 40-50 30-40 20-30 Q-5 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
ML A-4 100 100 95-100 70-80 0. 63-20. 0 0. 25-0. 30 4. 5-5. 5 Low.
GW or GP A-1 30-50 25-40 10-25 Q-5 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
ML A-4 100 95-100 95-100 65-75 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
GW or GP 30-55 25-50 10-25 Q-5 6. 30-20. 0 0. 03-0. 05 5.1-5.5 Low.
ML A-4 100 100 95-100 60-80 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
SP or SM-SP A-3 95-100 95-100 80-90 Q-10 6. 30-20. 0 0. 04-0. 06 5. 1-5. 5 Low.
Pt -------------------------------- --------------------------------------------4. 0-5. 0 High shrink;
low swell.
ML A-4 100 100 95-100 60-80 0. 63-2. 00 0. 25-0. 30 4. 5-5. 5 Low.
SM or ML A-4 100 95-100 90-100 40-60 2.00-6.30 0. 20-0. 25 5. 1-5. 5 Low.
OL A-5 or A-4 100 100 100 80-90 0. 63-2. 00 0. 28-0. 32 4. 5-5. 0 Low.
451-728--73----6
52 SOIL SURVEY
TABLE 6.-Estimated engineering
Classification
Soil series, land types, and map symbols
Depth to
seasonal
high water
table
Depth from 1----------------------1
surface of
*Susitna: 2 Ss, Sw _______________________________ _
For properties of Niklason soilE' in unit Sw, refer
to Niklason series.
Terrace escarpments: Te.
No valid estimates can be made.
Tidal flats 2 : Tf __________________________________ _
Tidal marsh 2: Tm _______________________________ _
Wasilla 2 : Wa ___________________________________ _
Whitsol: WhA, WhB, WhC, WhD, WhL __________ _
1 Depth to seasonal water table is not a factor.
2 Susceptible to flooding.
Ft.
(1)
0-1
0-3
2-4
typical
profile Dominant USDA texture
In. 0-45 Fine sandy loam, stratified fine sand, very fine
sand, and silt loam.
0-13
13-23
23-40
0-44
44-56
Stratified &ilt, clay, and very fine sand __________ _
Stratified silt, clay, and very fine sand-----------
Silt loam ____________________________________ _
Silty clay loam _______________________________ _
Silt loam, fine sandy loam, and silty clay loam ___ _
Silt loam, very fine sandy loam _________________ _
Very gravelly coarse sand ______________________ _
TABLE 7.-Engineering
[An asterisk in the first column indicates that at lea&t one mapping unit in thi~ series is made up of two or more kinds of soil. The soils
for referring to other :;eries that appear
Suitability as a source of-•
Soil series and map symbols
Highway
Topsoil Sand Gravel Road subgrade location ,
Bernice: BeF _______________ Poor: very shal-Fair: sandy rna-Good: a few Good ____________ Strongly sloping
low over coarse terial mixed cobblestone' to steep; ero-
material. with gravel. sion hazard
severe on ex-
posed embank-
ments.
Caswell: Ca ________________ Fair: sandy Silty and sandy Unsuitable in up-Poor in upper-Seasonal high
layers. rna terial in up-permost 30 most 30 inches; water table.
permost 30 inches; good in good in sub-
inches; very substratum. stratum.
gravelly sub-
stratum.
Chena: Ch _________________ Poor: very shal-Fair: sandy rna-Good: a few Good ____________ Subject to flood-
low over coarse terial mixed cobblestones. ing in places.
material. with gravel and
cobblestones.
Chulitna: CIA, CIB, CJC _____ Good ____________ Poor: silt loam Unsuitable in up-Poor in upper-Highly erodible
over very grav-permost 30 to mo:;t 40 in-on expo:;ed em-
elly substratum. 40 inches; ches; good in bankments;
good in sub-substratum. short irregular
stratum. elopes in places.
___,___
SUSITNA VALLEY A.RIEA, ALASKA 53
properties of the soils-Continued
Classification-Continued Percentage passing sieve-
Available
Permea-water Reaction Shrink-swell
No.4 No.10 No. 40 No. 200 bility capacity potential
Unified AASHO (4.7 (2.0 (0.42 (0.074
mm.) mm.) mm.) mm.j
SM or ML A-4 100 100 95-100 40-60
ln./hr. ln./in. of soil pH value
0. 63-2. 00 0. 20-0. 25 5. 1-5. 5 Low.
CL or CH A-6 or A-7 100 100 90-100 80-90 (3) (3) (3) (3).
CL or CH A-6 or A-7 100 100 90-100 80-90 (3) (3) 6. 1-7. 3 (3).
ML A-4 100 100 95-100 75-85 0. 63-2.00 0. 25-0. 30 5. 1-5. 5 Low.
CL A-6 or A-7 100 100 95-100 70-80 0. 20-0. 63 0. 28-0. 32 5. 1-5. 5 Moderate.
SM,ML A-4 100 95-100 80-90 35-60 0. 20-0. 63 0. 25-0. 30 5. 1-5. 5 Low to moderate.
ML A-4 100 100 95-100 70-80 0. 63-2. 00 0. 25-0. 30 5. 1-5. 5 Low.
GWor GP A-1 40-50 30-40 10-20 0-5 6. 30-20. 0 0. 03-0. 05 5. 1-5. 5 Low.
3 Variable.
interpretations of the soils
in such mapping units may have different properties and limitations, and for this reason it il:' necessary to follow carefully the instructions
in the first column of this table]
Embankments,
dikes, and
levees
Porous material;
rapid seepage.
Susceptible to
piping in up-
permost 30 in-
ches; porous
material in
substratum.
Porous material;
rapid seepage.
Susceptible to
piping in up-
permost 30 to
40 inches; por-
ous rna terial
in substratum.
Soil features affecting-
Pond reservoir
areas
Drainage of
cropland and
pasture
Grassed
waterways
Foundations for
low buildings
Not applicable__ Not applicable__ Not applicable__ Rapid permea-
bility; suscep-
tible to sliding.
Porous mateiial Moderate per-Not applicable __ Seasonal high
in substra-meability; water table.
tum; exces-seasonal high
sive seepage. watei table
in upper-
most 30 to 40
inches.
Porous mate-Not applicable __ Not applicable __ Rapid permea-
rial; excessive bility; suscep-
seepage. tible to occasion-
al flooding in
places.
Moderate per-Not applicable __ Highly erod-Low shear
meability in ible. strength and
uppermost 30 susceptibility
to 40 inches; to liquefaction
moderate in uppermost
seepage. 30 to 40 inches;
very gravelly
material below
a depth of 30 to
40 inches; ra-
pid permea-
bility.
Degree and kind of limitation for-
Septic tank ab-
sorption fields
Sewage
lagoons
Severe: strongly Not applicable.
sloping to
steep.
Severe: seasonal Severe:
water table. coarse mate-
rial in sub-
stratum.
Severe: subject Severe: rapid
to flooding. permeability.
Slight if slope is 0 Severe: rapid
to 7 percent; permeability
moderate if below a
slope is 7 to 12 depth of 30
percent; to 40 inches.
ground water
may be contam-
ina ted.
54
Soil series and map symbols
Topsoil
Clunie: Cn_ ----------------Unsuitable:
peat material.
SOIL SURVEY
Suitability as a source of-
Sand
Unsuitable:
peat material.
Gravel
Unsuitable:
peat material.
Coal Creek: Co_____________ Fair: seasonal Unsuitable: silt Unsuitable: silt
loam.
*Delyndia: DeA, DeB, DeC,
DeD, Dm.
For properties of Salama-
tof soils in mapping
unit Dm, refer to
Salamatof series in
this table.
*Dinglishna: Dn, Dr---------
For properties of Moose
River soils in mapping
unit Dr, refer to Moose
River series in this
table.
Flat Horn: FhA, Fh B _______ _
high water table. loam.
Fair: sandy
material below
a depth of 10
inches.
Poor: generally
wet; contains
strata of sand.
Good in surface
layer; subsoil
and substratum
interbedded
with fine sand.
Fair: fine sandy
material mixed
with silt in
places below a
depth of 12
inches.
Poor: generally
wet; strongly
cemented mate-
rial below a
depth of 14
inches.
Fair below a
depth of 20
inches; silt in-
terbedded with
fine sand.
Gravelly alluvial land: Ga ____ Unsuitable: Fair: sandy
material mixed
with gravel and
cobblestones.
sandy material
mixed with grav-
el and cobble-
stones.
Unsuitable: no
gravel.
Un:;uitable:
gravel.
Unsuitable:
gravel.
no
n<)
Good: subject
to flooding;
many cobble-
stones.
•
TABLE 7.-Engineering
Road subgrade
Unsuitable:
peat material.
Poor: silty
material~
Highway
location
Unstable peat
material; high
water table.
Susceptible to
frost action;
seasonal high
water table.
Good_ _ _ _ _ _ _ _ _ _ _ _ Susceptible to soil
blowing on ex-
posed embank-
ments; slopes;
cuts and fills
needed in places.
Fair: difficult to
excavate be-
cause of high
water table.
Poor: silt inter-
bedded with
fine sand.
Good: subject
to flooding.
High water table __
Susceptible to soil
blowing on ex-
posed embank-
ments.
Subject to
flooding.
Gravel pits: Gv _ _ _ __ _ _ _ _ _ ___ Unsuitable ______________________________________________________________________________ _
Homestead: HoA, HoB,
HoC, HoD, HoE.
Poor: very
shallow to
gravel.
Jacobsen: Ja_ _ _ _ _ _ ___ _ ___ __ Unsuitable:
very stony.
Fair: sandy
material
mixed with
gravel and
cobblestones.
Unsuitable:
very stony.
Good: 5 to 10
inches of silt on
surface.
Unsuitable:
very stony.
Good ____________ A few stones;
Poor: very
stony; high
water table.
hilly and
moderately
steep in places.
High water
table; seepage.
SUSITNA VALLEY ARIEA, ALA:SKA 55
interpretations of the soils-Continued
Soil features affecting-Degree and kind of limitation for-
Embankments, Pond reservoir Drainage of Grassed Foundations for Septic tank ab-Sewage
dikes, and areas cropland and waterways low buildings sorption fields lagoons
levees pasture
Unstable peat in High water Not applicable __ Not applicable __ Not applicable ____ Severe: high Not applicable.
uppermost 30 table; peat water table.
to 40 inches; deposits.
clayey substra-
tum has fair
stability.
Fair stability; Moderate seep-Moderate per-Not applicable __ Poorly drained; Severe: seasonal Severe: high
susceptible to age; seasonal meability; sea-low shear high water water table.
piping. high water sonal high strength; sea-table.
table. water table. sonal high water
table.
Sandy material; Sandy material; Not applicable __ Low available Fine sand; rapid Slight if slope is 0 Severe: rapid
porous. excessive water capac-permeability. to 7 percent; permeability.
seepage. ity; highly moderate if
erodible. slope is 7 to 12
percent; severe
if slope is more
than 12 percent;
ground water
may be contami-
nated.
Sandy material; Fluctuating Not applicable __ Not applicable __ Not applicable ____ Severe: high Severe: strong-
porous. water table; water table. ly cemented
strongly material in
cemented substratum
material at a depth of
below a 14 inches.
depth of 14
inches; lateral
seepage.
Susceptible to Moderate per-Not applicable __ Highly erodible __ Moderate perme-Slight: moderate Moderate:
piping. meability; ability; moder-permeability; moderate
moderate ate shear ground water permeability.
seepage. strength. may be contam-
ina ted.
Very gravelly Very porous; Not applicable __ Not applicable __ Subject to flood-Not applicable ____ Not applicable.
porous material. excessive in g.
seepage.
Very gravelly Porous; exces-Not applicable __ Not applicable __ Not applicable ____ Not applicable ____ Severe: porous
porous material. sive seepage. material.
Very gravelly Porous; exces-Not applicable __ Very shallow to Rapid perme-Slight if slope is Severe: rapid
porous sive seepage. gravel. ability; very 0 to 7 percent; permeability;
material. gravelly sand. moderate if coarse
slope is 7 to 12 material.
percent; severe
if slope is more
than 12 per-
cent; ground
water may be
contaminated.
Very stony _______ High water Not applicable __ Not applicable __ Poorly drained; Severe: high Severe: very
table; lateral high water water table. stony.
seepage. table.
56
Soil series and map symbols
Topsoil
Kalifonsky: Ka _____________ Fair: seasonal
Kashwitna: KsA, KsB, KsC,
Ks D , Ks E, Ks F.
*Killey: Kr -----------------
For properties of Moose
River soils in this
mapping unit, refer to
Moose River series in
this table.
high water
table.
Fair: shallow to
gravel.
Fair: seasonal
high water
table; silt
interbedded
with sand.
Lucile: Lu __________________ Good: very
gravelly
material below
a depth of 15
to 30 inches.
Mixed alluvial land: Me _____ Poor: variable
texture that
generally is too
coarse.
Moose River: Mr ___________ Poor: high water
Nancy:
NaA, NaB, NaC, NaD,
NaE, NaF.
table; stratified
sand and silt.
Good: very
gravelly mate-
rial below a
depth of 20 to
30 inches.
SO:IL SURVEY
Suitability as a source of-
Sand
Unsuitable in
uppermost 15
to 30 inches;
poor in sub-
stratum; sandy
material mixed
with gravel.
Fair: thin
surface layer
of silt loam;
sandy material
mixed with
gravel in
substratum.
Poor: seasonal
high water
table; silt
interbedded
with sand.
Poor: 15 to 30
inches of silt
loam; sandy
material mixed
with gravel in
substratum.
Poor: variable
texture; sandy
material mixed
with silt and
gravel.
Poor: high water
table; sandy
material inter-
bedded with
silt.
Fair to poor:
silt loam in
uppermost 20
to 30 inches;
sand mixed with
gravel in sub-
stratum.
Gravel
Unsuitable in
uppermost 15
to 30 inches;
fair in sub-
stratum; high
water table.
Good: thin
surface layer
of silt loam.
Poor: deep
silt and sand
sediment;
seasonal high
water table.
Good to fair:
15 to 30 inches.
of silt loam.
Fair: contains
strata of silt f
and sand.
Poor: high water
table; thick
silty and sandy
sediment.
Good to fair:
silt loam in
uppermost 20
to 30 inches;
very gravelly
material in
substratum.
TABLE 7.-Engineering
Road subgrade
Fair in substra-
tum; seasonal
high water
table; stones.
Good: thin
surface layer
of silt loam.
Fair to poor:
seasonal high
water table.
Good to fair:
15 to 30 inches
of silt loam.
Highway
location
Seasonal high
water table.
A few stones;
irregular slopes
in places.
Seasonal high
water table;
susceptible to
occasional
flooding in
places.
Shallow to
gravelly
material in
substratum.
Good ____________ Susceptible to
Poor: high water
table.
Fair: silt loam
in uppermost
20 to 30 inches.
flooding.
High water table;
susceptible to
flooding.
Hilly, or moderately
steep and steep
in places.
l
SUSITNA VALLEY ARIEA, ALASKA 57
interpretations of the soils-Continued
Soil features affecting-Degree and kind of limitation for-
Embankments, Pond reservoir Drainage of Grassed Foundations for Septic tank ab-Sewage
dikes, and areas cropland and waterways low buildings sorption fields lagoons
levees pasture
Susceptible to Seasonal high Seasonal high Seepage spots ___ Poorly drained; Severe: sea-Severe: coarse
piping in up-water table; water table. seasonal high sonal high material in
permost 15 porous water table. water table; substratum;
to 30 inches; material in ground water rapid perme-
porous mate-substratum may be con-ability.
rial in sub-permits ex-taminated.
stratum. cessive
seepage.
Susceptible to Very porous Not applicable __ Shallow to very Shallow to Slight if slope is Severe: rapid
piping in material in gravelly sand; rapidly perme-0 to 7 percent; permeability;
uppermost 10 substratum cobblestones. able material moderate if coarse mate-
to 15 inches; permits in substratum. slope is 7 to 12 rial; moderate
very gravelly excessive percent; severe to steep
porous mate-seepage. if slope is more slopes in
rial in sub-than 12 per-places.
stratum. cent; ground
water may be
contaminated.
Susceptible to Seasonal high Subject to Poorly drained __ Poorly drained; Severe: seasonal Severe: rapid
piping. water table; occasional subject to high water permeability
lateral flooding; occasional table; ground in substratum;
seepage. seasonal high flooding in water may be high water
water table. places; sea-contaminated. table.·
sonal high
water table.
Susceptible to Porous mate-Not applicable __ Very gravelly Moderate perme-Moderate: Severe: coarse
piping in rial in sub-material ability in seasonal high material;
uppermost 15 stratum below a depth uppermost 15 water table at rapid per-
to 30 inches; permits of 15 to 30 to 30 inches; a depth of 4 to meability
porous mate-moderate to inches. low shear 6 feet; ground below a depth
rial in sub-excessive strength; very water may be of 15 to 30
stratum. seepage. gravelly sand contaminated. inches.
in substratum.
Porous materiaL __ Porous ~aterial; Not applicable __ Not applicable __ Susceptible to Severe: suscep-Not applicable.
excess1ve flooding in tible to flooding.
seepage. places; variable
texture.
Susceptible to High water Not applicable __ Not applicable __ Not applicable ____ Severe: high Not applicable.
piping; fair to table; exces-water table;
poor stability. sive lateral susceptible to
seepage. flooding.
Highly suscep-Porous materi-Not applicable __ Highly erodible; Moderate perme-Slight if slope is Severe: rapid
tible to piping al in sub-gravelly ability and 0 to 7 percent; permeability;
in uppermost stratum spots. susceptibility moderate if moderately
20 to 30 inches; permits ex-to liquefaction slope is 7 to 12 steep to
porous mate-cessive seep-in uppermost percent; severe steep in
rial in substra-age. 20 to 30 inches; if slope is more places.
tum. rapid perme-than 12 percent;
I
ability in sub-ground water
stratum. may be con-
taminated.
58
Soil series and map symbols
Nancy: Cont.
N
R
NcA, NcB, NcC, NeD,
NeE.
iklason: Nk _______________
abideux:
RaA, RaB, RaC, RaD,
RaE, RaF.
RbA, RbB, RbC, RbD, RbE_
RdA, RdB, RdC, RdD,
RdE.
s alamatof: Sa ______________
s chrock: ShA _______________
Topsoil
Good: sandy
material below
a depth of 20
to 30 inches.
Fair in uppermost
10 to 30 inches;
stratified silt
and fine sand.
Good: very
gravelly mate-
rial below a
depth of 20 to
30 inches.
Fair: 15 to 20
inches of silt
loam over
gravelly mate-
rial.
Good: sandy
material in sub-
stratum.
Unsuitable:
peat.
Good: stratified
silt loam and
fine sand.
SOIL SURVEY
Suitability as a source of-
Sand Gravel
Good: silt loam Poor: sandy
in uppermost substratum.
20 to 30 inches;
fine sand in
substratum
mixed with silt
in places.
Fair: sandy and Good in sub-
silty material stratum:
mixed with sandy and
gravel and silty in upper-
cobblestones in most 10 to 30
substratum. inches.
Fair in sub-Good in sub-
stratum: stratum: un-
sandy and suitable rna-
silty material terial in up-
mixed with permost 20 to
gravel; un-30 inches.
suitable in up-
permost 20 to • 30 inches.
:Fair: silty rna-Good: 15 to 20
terial mixed with inches of silt
gravel and cob-loam over ~
blestones below gravelly mater-
a depth of 15 ial; cobble-
to 20 inches. stones. f
Fair: silt loam Unsuitable: no
over fine sand gravel.
in uppermost
15 to 25
inches.
Unsuitable: Unsuitable:
peat. peat.
Poor: excessive Unsuitable: no
fines. gravel.
Slikok: Sm _________________ Fair: high water Unsuitable: no Unsuitable: no
gravel. table. sand.
TABLE 7.-Engineering
Road subgrade
Fair: silt loam
over fine sand
in uppermost
20 to 30 inches.
Good ____________
Good below a
depth of 20 to 30
inches.
Good below a
depth of 15 to 20
inches.
Fair below a depth
of 15 to 25
inches; fine sand
mixed with silt
in places.
Unsuitable:
peat.
Poor: silt
loam.
Poor: mucky
silt loam; high
water table.
Highway
location
Highly erodible
on exposed em-
bankments;
hilly or moder-
ately steep in
places.
Susceptible to
occasional
flooding in
places.
Hilly, or mod-
erately
steep or
steep in
places.
Hilly and mod-
erately steep
in places.
Hilly and mod-
erately
steep in
places; highly
erodible on
exposed em-
bankments.
Unstable peat;
high water
table.
Erodible on ex-
posed embank-
ments.
Unstable mate-
rial; high water
table; suscep-
tible to frost
action.
SUSITNA VALLEY ARIEA, ALA:SKA 59
;:-.. Soil features affecting-Degree and kind of limitation for-
Embankments, Pond reservoir Drainage of Grassed Foundations for Septic tank ab-Sewage
dikes, and areas cropland and waterways low buildings sorption fields lagoons
levees pasture
Susceptible to Porous mate-Not applicable __ Highly erodible __ Moderate perme-Slight if slope is Severe: rapid
piping in rial in sub-ability and sus-0 to 7 percent; permeability;
uppermost 20 stratum per-ceptibility to moderate if moderately
to 30 inches; mits ex-liquefaction in slope is 7 to 12 steep to steep
porous sandy cessive seep-uppermost 20 percent; severe in places.
material in age. to 30 inches; if slope is more
substratum. rapid perme-than 12 percent;
ability in sub-ground water
stratum. may be con-
taminated.
Susceptible to Excessive seep-Not applicable __ Shallow to mod-Well drained; Slight to severe: Severe: rapid
piping in upper-age. erately deep rapid perme-subject to permeability.
most 10 over very ability below a flooding in
to 30 inches; gravelly depth of 10 to places; ground
porous grav-material. 30 inches; sus-water may be
elly material ceptible to occa-contaminated.
in substratum. sional flooding in
places.
Uppermost 20 to Porous material Not applicable __ Highly erod-Moderate permea-Slight if slope is Severe: rapid
30 inches sus-in sub-ible. bility and sus-0 to 7 percent; permeability;
ceptible to pip-stratum per-ceptibility to moderate if moderately
ing; very por-mits liquefaction in slope is 7 to 12 steep to
ous gravelly excessive seep-uppermost 20 percent; severe steep in
material in age. to 30 inches; if slope is more places.
substratum. porous mater-than 12 per-
ial in sub-cent; ground
stratum. water may be
contaminated.
Uppermost 15 to Porous mate-Not applicable __ Shallow to Shallow to very Slight if slope is 0 Severe: rapid
20 inches sus-rial in sub-very gravel-gravelly por-to 7 percent; permeability;
ceptible to stratum per-ly material; ous material. moderate if moderate to
piping; porous mits execs-cobble-slope is 7 to 12 steep slopes
very gravelly sive seepage. stones. percent; se-in places.
material in sub-vere if slope is
stratum. more than 12
percent.
Uppermost 15 to Porous mate-Not applicable __ Highly erod-Moderate permea-Slight if slope is 0 Severe: rapid
to 25 inches rial in sub-ible; sandy bility and sus-to 7 percent; permeability
highly sus-stratum per-spots. ceptibility to moderate if below a
ceptible to pip-mits execs-liquefaction in slope is 7 to 12 depth of
ing; porous sive seepage. uppermost 15 cent; severe if 15 to 25 in-
sandy material to 25 inches; slope is more ches; moder-
in substratum. loose fine sand than 12 percent. ate to mod-
in substratum. erately steep
slopes in
places.
Unstable peat ____ Peat; high wa-Not applicable __ Not applicable __ Not applicable ___ Severe: high wa-Not applicable.
ter table. ter table.
Susceptible to Moderate per-Not applicable __ Moderate per-Moderate per-Slight: moder-Moderate:
piping. meability; meability; meability; mod-ate permea-moderate
moderate moderate erate shear bility; ground permeabil-
seepage. available strength. water may be ity.
water ca-contaminated.
pacity.
Unstable mate-High water Patches of Poorly drained; Not applicable ____ Severe: high Severe: high
rial. table; high stones; high high water water table; content of
content of or-water table. table. ground water organic mat-
ganic matter. may be con-ter; high
taminated. water table.
60
Soil series and map symbols
*Susitna: Ss, Sw ___________ _
For properties of Niklason
soils in the Sw mapping
unit, refer to Niklason
series in this table.
Topsoil
Fair to good:
variable
texture.
Terrace escarpments: Te _____ Poor: generally
coarse textured.
SOIL SURVEY
Suitability as a source of-
Sand
Poor: contains
many strata of
silty material.
Poor: mixed
with silt and
gravel.
Gravel
Unsuitable:
gravel.
no
Fair: mixed
with silt and
sand.
TABLE 7.-Engineering
Road subgrade
Fair: stratified
sand and silt.
Good, but
difficult to
excavate
because of
steep slopes.
Highway
location
Susceptible to
flooding in
places.
Severe erosion
hazard; steep
slopes.
Tidal fiats: Tf_ _____________ Unsuitable _______ Unsuitable _______ Unsuitable _______ Unsuitable _______ Subject to fre-
quent flooding
by exception-
ally high tides;
unstable
material.
Tidal marsh: Tm ____________ Poor: clayey; Unsuitable _______ Unsuitable _______ Poor: high
susceptible to
flooding.
Wasilla: Wa----------------Good ____________ Poor: excessive
Whitsol: WhA, WhB, WhC,
WhD, WhE.
fines.
Good ____________ Ppor: silt loam
in the upper-
most 40 to 60
inches.
Unsuitable, deep
silty and
clayey materiaL.
Poor: silt loam
in the upper-
most 40 to 6c!
inches.
water table.
Poor: moderate
shrink-swell
potential.
Poor in upper-
most 40 to 60
inches; good
in substratum.
Susceptible to
frost heaving;
high water
table ;subjeet
to occasional
flooding.
Susceptible to
frost action.
Erodible on
exposed em-
bankments; hilly
and moderately
steep slopes
in places.
SUSITNA VALLEY AREA, ALASKA 61
interpretations of the soils-Continued
Soil features affecting-Degree and kind of limitation for-
Embankments, Pond reservoir Drainage of Grassed Foundations for Septic tank ab-Sewage
dikes, and areas cropland and waterways low buildings sorption fields lagoons
levees pasture
Susceptible to Excessive Not applicable __ Moderate Moderate Slight to severe: Severe: rapid
piping; porous seepage. permeability; permeability; subject to permeability
very gravelly moderate subject to flooding in in substratum.
material in available flooding in places; ground
substratum. water places. water may be
capacity. contaminated.
Variable texture; Not applicable __ Not applicable __ Not applicable __ Not applicable ____ Severe: steep Not applicable.
generally is slopes.
gravelly, stony,
and porous.
Clayey material; Not applicable __ Not applicable __ Not applicable __ Not applicable ____ Severe: high Unsuitable.
variable water table;
shrink-swell variable
potential. permeability.
Clayey material; High water Not applicable __ Not applicable __ Poorly drained; Severe: slow Severe: subject
variable table. slow perme-permeability; to occasional
shrink-swell ability; clayey high water flooding; high
potential. rna terial; high table. water table.
water table.
Fair stability; Seasonal high Moderately Poorly drained __ Poorly drained; Severe: seasonal Severe: sub-
susceptible to water table. slow perme-seasonal high high water ject to
piping. ability. water table. table; moder-flooding;
ately slow seasonal high
permeability. water table.
Susceptible to Moderate Not applicable __ Highly erodible_ Moderate Slight if slope is Severe: rapid
piping. permeability; permeability 0 to 7 percent; permeability
moderate and suscepti-moderate if in substratum;
seepage. bility to slope is 7 to 12 moderate to
liquefaction in percent; severe moderately
uppermost 40 if slope is 12 steep slopes
to 60 inches; to 20 percent; in places.
very porous ground water
gravelly rna te-maybe
rial in sub-contaminated.
stratum.
62 SO:TIL SURVEY
The tests for liquid limit and plastic limit measure the
effect of water on the consistence of soil material. As the
moisture content of a clayey soil increases from a very dry
state, the material changes from a semisolid to a plastic
state. As the moisture content is further increased, the
material changes from a plastic to a liquid state. The
plastic limit is the moisture content at which the soil
material passes from a semisolid to a plastic state. The
liquid limit is the moisture content at which the material
passes from a plastic to a liquid state. The plasticity indew
is the numerical difference between the liquid limit and
the plastic limit. It indicates the range of moisture content
within which a soil material is in a plastic condition.
Engineering properties of the soils
Table 6lists the soil series in the survey area and the map
symbols for each mapping unit and gives estimaJtes of soil
properties that are significant to engineering. The esti-
mates are based partly on test data in table 5 and partly
on experience with soils within the Area and that gained
in working with and observing similar soils in other areas.
In general, the estimates in table 6 apply only to the soil
depths indicated in the table, but these data are reasonably
reliable for soil material to a depth of about 5 feet. Depth
to bedrock is more than 10 feet for all the soils in the
survey area. Therefore, except for very deep excavations,
bedrock does not affect use of the soils.
Soil texture is described in table 6 in the standard terms
used by the Department of Agriculture. These terms take
into account relative percentages of sand, silt, and clay in
soil material that is less than 2.0 millimeters in diameter.
"Loam," for example, is soil material that is 7 to 27 percent
clay, 28 to 50 percent silt, and less than 52 percent sand.
If the soil contains gravel or other particles coarser than
sand, an appropriate modifier is added, as for example,
"gravelly loamy sand." "Sand," "silt," "clay," and some
of the other terms used in USDA textural classifications
are defined in the Glossary of this soil survey.
In table 6, permeability is estimated in inches of water
percolation per hour. The data are based on uncompacted
soils from which free water has been removed. The esti-
mates are based largely on texture, structure, and
consistence.
Available water capacity, expressed as inches of water
per inch of soil depth, is the capacity of a soil to hold water
available for use by most plants. It is the estimated amount
of water held in a soil between field capacity and the per-
manent wilting point of plants.
Reaction is the degree of acidity or alkalinity of a soil,
expressed as a pH value. The pH value and relative terms
used to describe soil reaction are explained in the Glossary.
In table 6 shrink -swell potential indicates the volume
change to be eX'pected of a soi•l with change in moisture
content. The estimates are based primarily on the amount
and kind of clay in the soil.
Engineering interpretations of the soils
Table 7 gives ratings of the soils according to their
suitability as a source of topsoil, sand, gravel, and road
subgrade. It also lists soil features that ·affect the suitabil-
ity of the soils...fgr several engineering practices. In S~ddi
tion, ratings of the limitations of the soils for use as sites
for septic tank absorption fields and sewage lagoons
given. The ratings and other interpretations are based
test data ·in table 5, on estimated soil properties in table
and on field experience.
Topsoil refers to soil maJterial, preferabiy rich in
matter, that is used as ·a topdressing on slopes, ~~·ww . ....,._
ments, lawns, gardens, and the like. The suitrubility
are based mainly on the texture and on the· """"."-'-'""·'"'"'
content of the soil. In this survey area, however, all of
soil materi•al used for topsoiiJ. generally needs additions
fertilizer for satisfactory results.
The ratings for sand and gravel are based on the
bility that ma;pped areas of the soils contain deposits
sand and gravel. The ratings do not reflect the quality
extent of the deposits. In the Susitna Valley Area,
soils on river terraces generally are underlain by l'"'"""~nrl
gravel, most of which is less ~than 3 inches in uutmetE~r
some places, however, the deposits contain many
stones. The gravelly material on moraines commonly
tains more fine-grained particles than that in other
and in places it contains many large stones and uvt.uu'"'""
Road subgrade refers to soil material that is used
build embankments. The suitabiEty ratings are based
the performance of soil material moved from borrow .
for this purpose. ·
Soil features considered in rating the soils for highway
locations are those that affect the overall performance of
the soils. The ratings are based on undisturbed soils.
Although the hazard of frost action is not considered in
the ratings indicated in t•able 7, it is a major concern where
the soils in this survey area are used for engineering pur-
poses. Most of the uplands is under a cover of wind-laid
silt •loam that raflges from less than 10 inches thick in
Homestead soils to more than 40 inches thick in \Vhitsol
soils. This material consists mainly of silt particles ·and is
susceptible to severe frost action. It generally is not good
ma;terial for cm~truction. The materia:! is soft and slippery
when wet and may not support heavy equipment, and it is
dusty when dry. In most of the well-drained soils on
uplands the silt loam generally is underlain by very
gravelly or sandy materia:l that is not susceptible to frost
a;ction.
The poorly drained soils in depressions, on flood plains,
and in seepage spots on moraines ·and terraces generally
are highly susceptible to frost action. About one-third of
the survey area is occupied by peaJt soHs in muskegs. These
soils are wet to the surface during most of the year and
are difficult to drain. Pe3it has no value as construction ma-
terial or as foundation material. If feasible, it should be
excavated before construction work begins.
Because it ·is difficult to maintain proper control of
moisture for compaction when soils are frozen, frost-
susceptible mruteria;l should not be used in constructing
embankments and other earthworks in winter.
Embankments, dikes, and levees are low structures de-
signed to impound or to divert waJter. The soil features
considered in rating the soils for these purposes are mainly
those that affect use of disturbed soil material for con-
structing earth fills.
The main feature considered in determining the suita-
bility of •the soils for pond reservoir areas is permea;bility
of the undisturbed soil, which affects seepage.
SUSITNA VALLEY ARIEA, ALASKA 63
The £.acto rs considered for providing drainage for crop-
land and pasture ·are the fe atures that affect the installa-
tion and performance of surface and subsurface drainage
system s. Among these features are permeability, seasonal
high water table, restricting layers, and r .elief. Drainage
of the soil s of this survey area for cropland and pasture
i s physically possi ble, but it cannot be justified economi-
cally until a greater percentage of the acreage of the
uplands is cl eared of vegeta;tion . Drainage of peat soils for
farming in the Area is not a;dvisaJble.
For grassed waterways, the soil features considered a re
those that affeot the establi shment, g rowth, and mainte-
nance of plants ·and the construction of waterways. Among
these features are stability (fig. 6), runoff, texture, and
stones on and in the soil.
Foundations for low buil dings are a ffected chiefly by
f eatures ·of t he undisturbed soil that influence its capacity
to support low buildings that hav.e normal foundation
loads. The substratum of the soil is evaluated beca,u se this
layer generally provides the b as e for foundations . Specific
values of bearing strength are not considered .
Septic tank absorption fields and sewage lagoons a re
influenced mainly by su ch soil f eatures as seasonal high
water table, su sce ptibility to flooding , permeability, and
slope. In tabl e 7 ratings of slight, moderate, and severe
indicate the degree to which these featu res limit the u se
of the soil s in this survey area for septic tank absorption
fi elds and se wage lagoons.
Formation and Classification of Soils
In this section the fa ctors that have a ffe cted the form a-
tion of soils in the Susitna Valley Area are discu sse d, and
important processes in the differentiation of soil horizons
are b6efly d esc ribed. Then, the current system of soil classi-
fication i s explained , and the soil se ries represented in the
survey area are p l aced in some of the categories of this
system . The soil series of the Susitna Valley Area, includ-
ing a profile r epresentative of each series, are d esc ribed in
the section "Descriptions of the Soils."
Factor s of Soil Formation
Soil is produced by the action of soil-forming processes
on materials d epo sit ed or acctmmlated by geologic forces .
The characteristics of the soil at any given point are deter-
mined by the inter action of five major factors : (1) p ar-
ent material , ( 2) climate, ( 3) p l ants and animal s, ( 4)
r elief , and ( 5 ) time.
Climate and plants and animals are the active factors
of so il form ation. They act on the parent material that
has accumulated through the weathering of rocks and
slowly change it into a natural body with genetically r e-
l ated horizons. The effects of climate and plants and ani-
mal s are conditioned by r elief. The parent material also
affects the kind of profil e that can be formed and, in ex-
treme cases, determines it al mo st entirely. Fina lly, tim e
Figur e G.-Ex p osed roadbru1ks in a Nan cy s ilt loa m, sandy s ubstratum. T h ese soils are highly s u scep t ible to eros ion .
64 .SO:FL SURVEY
is needed for the changing of parent material into a soil.
It ma:y be ID"';1C~ or little, but ~orne time is always required
for drfferentiatwn of s01l honzons. Generally, a long time
is needed for distinct horizons to form.
Parent material.-Parent material is the unconsolidated
mass from which ·a soil forms. It determines the limits
of the chemical and mineral composition of the soil.
In the Susitna Valley Area, the dominant soils on up-
lands formed in a mantle of silty deposits over sandy or
gravelly m!l-terial o.n t~rr~ces and glacial till (10). The
loess deposits contam sigmficant amounts of volcanic ash
_(15). The thickness of the loess ranges from 5 inches, as
m the Homestead soils, to more than 40 inches as in the
Whitsol soils. The loess deposits generally are ~hallow in
the southeastern section of the Area and thick in the cen-
tral part. Most of the underlying terrace material consists
of rounded gravel, cobblestones, and sand. In several large
areas of Rabideux and Nancy soils, however, the gravelly
material is covered by thick deposits of fine sand. Gen-
eraUy, the glacial till is loose and gravelly, but it contains
a somewhat higher proportion of fine-grained material
than the terrace deposits.
Soils <?n flood _Plains. along the major streams of the Area
for:ned m ~trati:fied silty and sandy water-laid sediment.
rhis material ranges from a few mches in thickness, as
m the Chena soils, to many feet in thickness as in the
Schrock and Susitna soils. The sediment wa; deposited
over very gravelly and cobbly stream deposits.
The peat soils in the Clunie and Salamatof series
formed principally from the remains of mosses sedges
and other low-growing plants. Peat deposits cdmmonly
are many feet deep and are in bogs or muskegs that range
from less than an acre to many square miles in size.
Olim_at~.-The climate of the Susitna Valley Area gen-
era_lly I~ mfluenced by the cold, dry, continental climate
of mterwr Alaska and the mild maritime climate of coastal
areas bordering the Gulf of Alaska. It is characterized
by C?O~ su!illllers and moderat~ly col~ winters. The annual
preCipitatiOn ranges from 20 mches m the extreme south-
eastern part of the Area to 29 inches in the extreme north-
ern p~rt. Snow generally covers the surface from about
the middle of October to the end of April, and accumula-
tions commonly are 2 to 5 feet deep throughout much of
the Area. Because e':aporation and transpiration rates are
~ow, mu?h ~f the ra~nfall perco.lates through the soil and
IS effective m leachmg. The soils therefore are acid and
low in major plant nutrients. There is no permafrost in
the Area.
Plants and animals.-Plants, burrowing animals in-
sects,_ bacteria, and fungi are important in the form~tion
of s01ls. They add to the ~upply of organic matter, nitro-
gen, and other plant nutrients and alter the structure and
porosity of the soils.
In this survey area the upland soils generally support
vege~ation mainly of paper birch, white spruce, and
quaking aspen. Many of the poorly drained soils support
black sp·rnce or dense pakhes of willow and alder. The
vegetation of most of the very poorly drained soils in
muskegs, howeve:, consists ~f thick moss, sedges, and low
~hrubs. _InformatiOn concernmg t~e vegetation in the Area
IS provided under "Woodland," m the section "Use and
ManagemenLoi._the Soils."
Because of the cool climate in the Susitna Valley Area,
biological activity is relatively slow. Woodland litter and
other plant remains decompose slowly because they tend
to accumulate on the surface of the soil. This mat of or-
ganic mruterial commonly is llh to 4 inches thiok on the
well-drained soils, and it is thicker on the poorly drained
soils. The insulating effect of the mat tends to delay thaw-
ing of the soils in spring.
Relief.-In this Area the influence of relief on soil
formation is strongest in its effect on natural drainage.
Soils in depressions and in low-lying areas commonly
show characteristics associated with wetness. Those on
uplands, including the Chulitna, Delyrrdia, Flat Horn
Homestead, Kashwitna, Nancy, Rabideux, and "Whitsol
soils, genemlly have colors and other characteristics that
in~icate good drainage. Differences among well-drained
soils are largely the result of factors other than relief.
For example, little consistent relationship exists between
thickness of the mantle of loess or the distinctiveness of
subsoil formation and steepness of slope or other features
of relief.
Time.-A long time is needed for formation of soils that
have distinct horizons. The length of time that parent
material has been in place generally is reflected in the
degree of formation of the soil profile.
All the soils of the Area formed after the recession of the
last ice sheet and the subsequent deposition of loess and
volcan~c ash. Profile formation in t~e uP.land soils gen-
erally Is.much ~ore advanced, especmlly m the Chulitna
and Rab1deux soils of the northern parts of the Area, than
it is in the soils of the Matanuska Valley Area, which lies
to the east ( 16). Although much of this difference in profile
formation can be attributed to the more intensive leaching
that results front heavier rainfall in the Susitna Valley
Area (15), time also is an important :factor. The processes
of soil formation have been at work for a much longer
~ime in the loess deposits of the Susitna Valley Area than
m those of mos) the Matanuska Valley Area, where loess is
still being deposited. Most of the weil-drained soils in the
Susitna Valley Area that formed in loess have a bisequal
profile, charact~rized by a buried sequum that has horizons
similar to those in the upper sequum. The distinct horizons
of the buried sequum indicate a long interim stage between
two separate periods of silt deposition.
Classification of Soils
Soils are classified so that we can more easily remember
their significant characteristics. Classification enables us to
assemble knowledge about soils; to see their relationship
to one another and to the whole environment; and to
develop principles that help us to understand their be-
havior and response to kinds of treatment.
Thus, in classification, soils are placed in narrow cate-
gories that are used <in detailed surveys so that knowledge
about the soils can be organized and applied in managing
farms, fields, and woodland; in developing rural areas ; in
engineering work; and in many other ways. The soils are
placed in broad classes to facilitate study and comparison
in large areas, such as countries and continents.
Two systems of classifying soils have been used in the
United States in recent years. The older system was
adopted in 1938 (B) and later revised (19). The system
currently used was adopted for general use by the National
'.
SUSITNA VALLEY AR'EA, ALASKA 65
·~.-.n""'·,..tive Soil Survey in 1965. It is under continual
Therefore, readers interested in this system should
the latest literature available (17, 131). The soil
of the Susitna Valley Area are placed in some cate-
of the current system in table 8.
and uniform in texture; by Typic Oryofouvents, which are
well drained and stratified; and by Typic Oryaquents,
which are poorly drained.
Histosols are composed primarily of organic material.
The current system of classification has six categories.
· · with the broadest, these categories are order,
They are represented in the Susitna Valley Area by T erric
Borofibrists, which are moderately deep over a mineral
substratum, and by Oryic Sphagnofibrists, which consist o£
deep sphagnum moss peat. group, subgroup, family, and series. In this
criteria used as a basis for classification are soil
that are observruble and measurable. The prop-
are chosen, however, so that the soils of similar origin
lnceptisols, soils in which the parent material has been
modified, have .weakly expressed horizons that are ohar-
acteristic of those in other orders. In the Susitna ¥alley
Area, the only Inceptisols that ·are recognized are soils
that formed under cold, wet conditions. These soils, the
Cryaquepts, are gray, bluish, or greenish and contain
brown or reddish-brown mottles and streaks. The Typic
Oryaquepts lack a thick dark upper horizon •and ·a thick
ma;t of organic material on •the surface. Aerie Oryaquepts
have characteristics associated with wetness, but they are
browner than the Typic Cryaquepts. Humic Oryaquepts
have a thick, dark-colored surface horizon. Histic
Oryaquepts have a fairly thick accumulation of organic
material on the surface.
grouped together. The placement of some soil series in
current system of classification, particularly in £am-
may change as more precise information becomes
"'.u'"'"""· The categories of the current system are briefly
in the paragraphs that follow:
Ten soil orders are recognized. They are Enti-
ertisols, Inceptisols, Aridisols, Mollisols, Spodosols,
·~""""'"u' Ultisols, Oxisols, and Histosols. The properties
to differentiate the soil orders are those that tend to
broad climatic groupings of soils. Two exceptions, the
.cwc~wv•o and the Histosols, occur in many kinds of climate.
Spodosols are soils in which leaohing ( eluvia-tion) has
resulted in an accumulation of organic carbon, together
with iron and aluminum, in one horizon of the profile. This
hor.izon generally is dark brown or dark reddish brown.
kbove the illuvial horizon a light-gray eluvial horizon
commonly is at the surface of the mineral soil.
The four soil orders represented in the Susitna Valley Area
are Entisols, Histosols, Inceptisols, and Spodosols.
· Entisols have few, if any, clearly expressed characteris-
In the Susitna Valley Area, Entisols occur on alluvial
in material recently deposited by water. They are
o:repr(\SeJo.ted by Typic Oryorthents, which are well drained
Series
:··Bernice _______ _
CaswelL ______ _
·· Chena ________ _
Chulitna ______ _
Clunie ________ _
Coal Creek ____ _
Delyndia ______ _
Dinglishna ____ _
Flat Horn _____ _
Homestead ____ _
Jacobsen ______ _
Kalifonsky ____ _
Kashwitna ____ _
Killey _________ _
Lucile _________ _
Moose River_ __ _
Nancy ________ _
Niklason ______ _
Rabideux _____ _
SalamatoL ____ _
Schrock _______ _
Slikok _________ _
Susitna ________ _
Wasilla ________ _
WhitsoL ______ _
TABLE 8.-0lassijication of soil series of Susitna Valley Area
Current classification 1938 classification
l-----------------------------------------------.----------1-----------------
Family
Sandy-skeletal, mixed ___________________ _
Coarse-loamy, mixed ____________________ _
Sandy-skeletal, mixed ___________________ _
Coarse-silty, mixed _____________________ _
Loamy, mixed, euic _____________________ _
Coarse-silty, mixed, acid ________________ _
Sandy, mixed __________________________ _
Sandy, mixed, ortstein __________________ _
Coarse-loamy, mixed ____ -----------------Loamy-skeletal, mixed __________________ _
Loamy-skeletal, mixed, acid _____________ _
Coarse-silty over sandy or sandy-skeletal,
mixed, acid.
Coarse-silty over sandy or sandy-skeletal,
mixed.
Coarse-loamy over sandy or sandy-skeletal,
mixed, acid.
Coa~se-silty over sandy or sandy-skeletal,
m1xed.
Coarse-loamy, mixed, acid _______________ _
Coarse-silty over sandy or sandy-skeletal,
mixed.
Coarse-loamy over sandy or sandy-skel-
etal, mixed, acid.
Coarse-silty over sandy or sandy-skeletal,
mixed. Dysic _________________________________ _
Coarse-loamy, mixed ____________________ _
Coarse-silty, mixed, acid ________________ _
Coarse-loamy, mixed, acid _______________ _
Fine-loamy, mixed, acid _________________ _
Coarse-silty, mixed ______________________ _
Subgroup Order Great group
Typic Cryorthods __________ Spodosols_____ Podzols.
Sideric Cryaquods _________ Spodosols_____ Podzols.
Typic Cryorthents _________ Entisols ______ Alluvial soils.
Typic Cryorthods_ _ _ _ _ _ _ _ _ Spodosols_____ Podzols.
Terrie Borofibrists__ _ _ _ _ _ _ _ Histosols_____ Bog soils.
Humic Cryaquepts ________ Inceptisols ____ Humic Gley soils.
Typic Cryorthods _________ Spodosols _____ Podzols.
Typic Cryaquods__ _ _ _ _ _ _ _ _ Spodosols_____ Ground-Water Podzols.
Typic Cryorthods_ _ _ _ _ _ _ _ _ Spodosols_____ Podzols.
Typic Cryorthods_ _ _ _ _ _ _ _ _ Spodosols_ ___ _ Podzols.
Histic Cryaquepts _________ Inceptisols ____ Humic Gley soils.
Typic Cryaquepts _________ Inceptisols ____ Low-Humic Gley soils.
Typic Cryorthods_ _ _ _ _ _ __ _ Spodosols____ _ Podzols.
Aerie Cryaquepts__________ Inceptisols____ Low-Humic Gley soils.
Sideric Cryaquods_ _ _ _ _ _ _ _ _ Spodosols_____ Podzols.
Typic Cryaquents _________ Entisols ______ Low-Humic Gley soils.
Typic Cryorthods_ _ _ _ _ _ _ _ _ Spodosols_____ Podzols.
Typic Cryofluvents ________ Entisols ______ Alluvial soils.
Typic Cryorthods _________ Spodosols _____ Podzols.
Cryic Sphagnofibrists_ _ _ _ _ _ Histosols_____ Bog soils.
Typic Cryorthods _________ Spodosols _____ Brown-Podzolic soils.
Histic Cryaquepts _________ Inceptisols ____ Humic Gley soils.
Typic Cryofluvents_ _ _ _ _ _ _ _ Entisols_ _ _ _ _ _ Alluvial soils.
Humic Cryaquepts ________ Inceptisols ____ Low-Humic Gley soils.
Typic Cryorthods _________ Spodosols _____ Podzols.
66 SOlL SURVEY
During the process of formation, these soils have become
very strongly acid. In this survey ,area most of the
Spodosois have a bisequal solum. The upper sequence of
horizons generally ranges from 8 to 10 inches in thickness
and rests on a buried sequum rubout 8 to 12 inches thick.
In general, the characteristics of Spodosols are more
strongly e:x!pressed in soils in the northern ·and western
parts of the Area. These soils have darker ill uvial horizons
and contain more ·concretions of iron oxide than the more
weakly expressed Spodosols in the eastern part of the
Area.
Typia Oryorthods are well-drained Spodosols that are
present in cold regions ·and have ·a modemte amount of
organic ma;tter in the illuvial horizon. Typia Oryaquods
are cold Spodoso'ls that have characteristics associated
with wetness and, in ~addition, have a thick very firm
illuvia1 h?l'izon. Sfil:eria Oryaguods. are cold Spodosols
that contam mottles m the eluvial horizon-
S"?BORDERS. E~ch order is ~ivided into. s~borders, pri-
marl'ly on the basis of those sOil characteristiCs that seem
to produce classes having the greatest genetic similarity.
Suborders narrow the broad dimatic range of the orders.
The soil properties used to distinguish suborders are
mainly those that reflect the presence or absence of water-
logging or soil differences that result from the effects of
climllite or vegetation.
GREAT GROUPS. The suborders are divided into great
groups on the basis of uniformity in the kinds and sequence
of major soil horizons and features. The horizons used ~as
~ basi~ for distin~ishing between great groups are those
m wluch (1) clay, Iron, or humus have ~accumulated· (2) a
pan has formed that interferes with growth of' roots,
movement of water, or both; or (3) a thick, dark-colored
surface horizon has formed. The other features commonly
used are the self-mulching properties of clay, soil tem-
pera~ure, m~jor differe~ces in. chemical composition
(mamly calcmm, magnesmm, sodmm, and potassium), or
the dark-red or dark-brown colors associated with soils
formed in materia:l weathered from basic rock.
SUBGROUPS. Great soil groups are divided into sub-
groups. One of ·these represents the central, or typic, seg-
ment of the group. Other subgroups, ca'lled intergrades,
have properties of the group, but have one or more prop-
erties of another great group, suborder, or order. Sub-
groups may also 'be made for soils that have properties
that intergrade outside the range of any other great group,
suborder, or order.
F Al\HLIES. FamiEes ,are separated within a subgroup
primarily on the basis of properties important to the
growth of plants or to the behavior of soils when used for
engineering. Among the properties considered are tex-
tu~e, mineralogy,. reaction, soil te~perature, pe~eability,
thickness of horizons, and consistence. A family name
consists of a series of adjectives preceding the name of a
subgroup. The adjectives used are the class names for
texture, mineralogy, temperature, and so on.
SERIES. The se11ies is a group of soHs that formed from
a particu'lar kind of 'P'arent material and have major hori-
zons that, except for texture of the surface layer, are simi-
lar in important characteristics and in arrangement in the
profile. The soils are given the name of a geographic
location near~Iace where that series was first observed
and mapped.
General Nature of the Area
This section is provided mainly for those ~who are un-
familiar with the survey area. Factors discussed are
physiography and drainage; geology; clima;te; vegeta-
tion; and history, settlement, and industry.
Physiography and Drainage
The Susitna Valley Area includes the eastern part of
the lowlands along the Susitna River. It lies to the north
of Cook Inlet ·and extends northward between the Tal-
keetna Mountains and the Alaska Range. The Area gener-
ally slopes from north to south. Most of it is drained by the
Susitna River and its tributaries, but a few strea;ms that
flow directly into Cook Inlet drain the southeastern part.
Although most of the Area is between 50 to 500 feet above
sea level, extreme elev,ations range from sea level at the
tidal flats along Cook Inlet to slightly more than 1,300
feet on a few glacial moraines near Talkeetna.
The Susitna, the largest river in the Area, and its flood
plains range from ,about a half mile to several miles in
width. It is a braided, glacier-fed stream that is laden
with silt ~and originates in the Alaska Range. Two of its
major tr~butaries, the Chulitna and Yentna Rivers, also
flow from the Alaska Range. Other streams originate in
small glaciers in the Talkeetna Mountains to the east ( 14).
The Little Susitna River and 'a few other streams in the
southeastern part of the Area flow directly into Cook Inlet.
A few of the smaller streams begin in the lowlands or on
mountain foot slopes and generally are clear. The water
level in most of the larger rivers and streams in the Area
fluctuates rapidly. "'n many places the lowlands are sus-
ceptible to flooding during periods of glacial melting
or when rainfall is heavy in the mountains.
In the southern part of the Area and along major
streams, the relilff generally is nearly level to undulating.
Low hills where irregular slopes are rolling to steep ~are
dominant in the eastern and northern parts of the Area.
Ponds, lakes, anB. many muskegs where drainage is very
poor ocour throughout most of the •area.
The muskegs and a belt of low-lying tidal plains next
to Cook Inlet ·are treeless, but most of the Area is wooded.
Paper birch, _quaking aspen, and white spruce,are dominant
on uplands. Cottonwoods (balsam poplar and black cotton-
wood) are common on the flood plains of the larger streams,
and black spruce grows on the edges of muskegs.
Geology
The Susitna Valley Area is underlain by bedrock that
consists mainly of weakly consolidated coal-bearing rocks
of Tertiary age (934). All of the bedrock is covered by
thi~k deposits of glacial drift and alluvial sediment that
consist mainly of gravelly 'and sandy materia:} (12). Most
of the Area has a mantle of silty wind-raid deposits that
contain large quantities of volcanic ash. The loess ranges
from a few inches to 5 or 6 feet in thickness.
Broad terraces and outwash plains are dominant in the
southern part of the survey area ~and along the larger
streams in the northern part. Hilly moraines ·are common
in the eastern and northern sections; large tracts of ground
moraine are west of the Susitna River, and flood plains 'are
along the major rivers. Tidal plains as much as 2 miles
SUSITNA VALLEY ARIEA, AL.A!SKA 67
border Cook In'let. Irregularly shaped, very poorly
muskegs that range from a :few acres to several
rucres in size :are in most parts o:f the Area. Ponds
lakes are common. Mo~t o:f them are irregular in shape,
near the ground morame they generally are long and
and slope :from north to south.
nn.M""'""~"·" o:f gravel 'and sand on terraces and outwash
are well sorted and nearly :free o:f fine
Moramal deposits genera1ly consist o:f poo-rly
very gravelly and stony material. The sediment on
plains consists ma'inly o:f stratified deposits o:f silt
fine sand that range :from a :few inches to 6 :feet thick
gravel. The tid~l plains •are dominantly cl?-yey. Most
muskegs cons1st o:f coarse, extremely amd peat de-
mainly :from sphagnum moss and sedges. Despite
exph~rations :f~r oi'l in many. p1;1rts o:f the Area, the
geologica~ deposits of e?onoi?JC Importance are sand
gravel, wh1ch are used prnnari'ly :for road construction.
Climate 4
The climate o:f the Susitna Valley Area is influenced by
marine conditions in the south and by continental condi-
tions in the west, north, and east. The temperature ranges
:from 48° below zero to 93° above zero. 'Dhe average daily
maximum temperature in summer is in the mid to upper
60's, but temperatures of 32° F. or lower have been re-
corded during every month in summer. In winter the
average minimum temperature ranges :from about zero to
13°. The :freeze-free period averages about 80 to 95 days.
Tables 9 and 10, compiled :from records kept at Susitna
and at Talkeetna, give temperature and precipitation data
considered representative o:f the Susitna Valley Area.
The average annual precipitation o:f about 20 inches or
more greatly exceeds the amount o:f precipitation received
• By HAROLD W. SEARBY, regiooal climatologist for Alaska Na-
tional Wewther Service, U.S. Department of Commerce. '
TABLE 9.-Temperature and precipitation data
Month
January _______________
February ______________
~arch ________________
A ril Mtay_~~=============== June __________________
July __________________
August _______________
SepteiUber ____________
October _______________
November_ ____________
Deceinber _____________
Year _____________
January ________________
February _______________
March _________________
ApriL _________________
~~=================== i~~~;t:~~============= SepteiUber _____________
October ________________
Noveinber ______________
Deceinb~r ______________
Year ______________
Temperature 1
Average
daily
maximum
23
31
35
48
60
69
70
67
57
44
31
24
47
20. 1
25. 6
32. 2
44. 6
.56. 1
65. 9
68. 0
64. 4
55. 6
41. 4
26. 2
18. 6
43. 2
Average
daily
minimum
2
13
12
24
32
41
46
44
38
27
13
5
25
0. 6
3. 7
6. 3
29. 2
32.7
43. 8
47. 6
44. 7
37. 0
23. 9
8. 6
.2
23. 2
SusiTNA, ALASKA
Two years in 10 will have
at least 4 days with-
Maximum
temperature
equal to or
higher
than-
40
43
45
58
71
80
79
74
65
54
41
41
-----------
Minimum
temperature
equal to or
lower
than-
-30
-17
-9
10
20
33
38
34
27
3
-8
-27
------------
TALKEETNA, ALASKA
37 -27
41 -23
44 -19
55 -1
69 2:1
81 3'i
80 42
76 34
64 27
54 -2
40 -19
37 -31
------------------------
Average
total
Inches
1. 38
1. 28
1. 16
. 88
1. 46
1. 69
2. 55
5. 52
5. 07
3. 53
1. 82
1.71
28. 05
1. 86
1. 69
1. 51
. 98
1. 37
2. 11
3. 25
5. 14
4. 87
2. 63
1. 63
1. 57
28. 61
Precipitation
One year in 10 will
have-
Less
than-
Inches
0. 29
. 34
. 60
. 37
. !)9
. 52
1. 24
2. 52
2. 49
1. 84
. 16
.11
---------
0. 05
. 02
. 03
. 05
. 28
. 22
1. 13
. 97
1. 81
1. 03
. 09
18
----------
More
than-
Inches
4. 52
2. 13
1. 68
1. 61
2. 34
2. 94
3.77
9. 71
7. 84
4. 20
4.40
4. 20
---------
5. 55
3. 55
7. 22
3. 46
3.47
.5. 07
6. 49
11. 91
9. 91
4. 47
4. 46
4.. 14
----------
Days with
snow
cover
Nurnber
29
28
31
17
1
0
0
0
0
3
18
26
153
31
28
31
26
8
0
0
0
(2)
12
25
31
192
Average
depth of
snow on
ground
last day
of month
Inches
17
13
12
1
0
0
0
0
0
1
4
10
----------
29
3'i
2 7
8
0
0
0
0
0
5
13
22
----------
1 MaxlinUin a~d IniniinUin teiUperature data for Susitna are for period 1933-47. Maximuin and Ininiinuin teinperature data for Tal-
keetna are for penod 1941-62.
2 Less than 0.5 day.
68 SOIL SURVEY
TABLE 10.-Probability of specified temperatures in spring and in fall
SUSITNA, ALASKA
Dates for given probability and temperature of-
Probability
16° F. or 20° F. or 24° F. or 28° F. or 32° F. or
lower lower lower lower lower
Spring:
1 year in 10 later than __________________________ May3 May13 June 1 June 11 June 25 2 years in 10 later than ________________________ April30 May 11 May 29 June 7 June 22 5 years in 10 later than ________________________ April16 May5 May 18 May 31 June 13
Fall:
1 year in 10 earlier than _______________________ October 8 September 23 September 5 August 30 August 20 2 years in 10 earlier than ______________________ October 11 September 25 September 8 September 2 August 23 5 years in 10 earlier than ______________________ October 21 October 3 September 19 September 12 September 2
TALKEETNA, ALASKA
Spring:
1 year in 10 later than _________________________ May4 2 years in 10 later than ________________________ May 1 5 years in 10 later than ________________________ April19
Fall:
1 year in 10 earlier than _______________________ October 5 2 years in 10 earlier than ______________________ October 7 5 years in 10 earlier than ______________________ October 15
annuairly in Alaska's principal farming areas, except in the
southern :part of the Kenai Peninsula. The heaviest rain-
fall occurs late in the ·growing season, but moisture in the
soil from melted winter snow leaves the soil saturated dur-
ing the early part of the growing season. Thunderstorms
occur in summer, but hail is mre.
In summer surface winds generaJlly are light in inten-
sity. From time to time in winter, however, windspeeds
reach 20 to 40 miles ·an hour, and the ·average velocity is
12 miles or less per hQIUr. The prevail'ing direction of the
wind generally is from the north, though at times the
direction is from the south.
Vegetation
Less than 1 percent of the a'Creage in natural vegetation
in the Susitna Valley Area has :been 'Cleared for cro:ps or
for other uses. About three-fourths of the survey area is
wooded. The remaining one-fourth consists largely of mus-
kegs, where drainage is very poor, and of t'idal piLains that
support low-growing phnts. The root system of most
plants, including trees, generally is shrullow and is con-
centrated in the surface layer of the soil.
The kinds of trees in the Area and the age, density, and
rate of growth of the stands depend largely upon such
factors as characteristics of the sml, relief, past forest fires,
and harvesting prructices. The :principal woody vegetation
in the Area consists of a mixture of :paper birch and white
spruce (12). White spruce is the chmax tree, but only a
few pure stands remam, largely because of past forest fires
and cutting pra:ctices. Slow-growing black spruce is com-
mon along the~es of muskegs and in other areas where
drainage is poor. Quaking aspen is dominant on a few
May 5 May 18 May 29 June 13
May3 May 15 May 28 June 10
April 25 May7 May 23 June 3
September 27 September 19 September 4 August 15
October 1 September 22 September 7 August 19
October 9 September 29 September 17 August 30
well-drained sites, and cottonwood is common on low-lying
alluvial plains. Alder and willow grow in thrckets on
poorly drained so<ils along small streams. Most of the
stands have a dense understory of shrubs ·and other plants.
Additional infO'I'mation concerning kinds 'of trees in the
Susitna Valley Are'a is provided under "Woodland" in
the section "Use and Management of the Soils."
Muskegs, mainly very poorly dra:ined :peats, make up the
principal nonwobded areas. These areas genemlly have a
thick mat of sphagnum moss on the surface. Other plants
include cottongrass, Labrador-tea, bog birch, dwarf wil-
lorw, bog blueberry, crowberry, and (?Jloud'berry.
The tidal :plains ·along Cook Inlet also are not wooded.
The vegetation consists mainly of sedges, forbs, and
grasses ( 7) .
History, Settlement, and Industry
Before the discovery of gold late in the 19th century,
fur trading was the principal occupation in the Susitna
Vialley Area, and explorations generally were confined to
coastal regions. One of the first significant recorded ex-
peditions into the Area was made by W. A. Dickey and
party in 1896 (3). The group made geological investiga-
tions in sections of the valleys of the Susitna and Chulitna
Rivers. In addition, they described and named Mt.
McKinley.
Important gold discoveries in various parts of Alaska,
including the region around Cook Inlet, led to increased
prospecting and explorations (9). Placer gold was dis-
covered in the district around Willow Creek in 1897 and
in other nearby areas shortly thereafter. Although fur
trading stations had been previously established in Susitna
l
l
SUSITNA VALLEY AREA, .ALASKA 69
and in Talkeetna, the trading posts 1and roadhouses that
were constructed along trails and routes to the goldfields
were the first significant permanent settlements.
Other settlements were established following construc-
tion of the Alaska Railroad, which connects Seward and
Fairbanks. During the construction, which began on Knik
Arm in 1915, several railroad camps were erected along
the route. Kashwitna, Oaswell, Montana, Sunshine, and
Chase were the main camps in the Susitna Valley. Some of
these camps became small trading centers and were rail-
way stations for many years <after the construction period.
Though their names remain on a few maps of Alaska, most
of these places are now abandoned or serve only as rail-
road sidings.
Homesteading of Federal land in the Area reached a
peak in the 1950's. Most homesteads were near the railroad
and along the Petersville Road leading from the Susitna
River to placer mines about 40 miles to the west. Since
Alaska achieved statehood in 1959, most public lands have
been transferred to State jurisdiction, though a few areas
have been sold at public auctions. Homesteading resulted
in a few permanent rural settlements in the Area, but less
than a thousand acres are estimated to have been cleared
for crops. Many areas transferred to private ownership
consisted of small tracts for recreatioll!al or business uses.
The recent construction of a major highway almost
parallel to the Susitna River in the northern part of the
Area has resulted in increased recreational activities. Many
of the lakes, streams, and woodlands are more readily
accessible and are used for a variety of activities. The
Nancy Lake Recreational Area, a new State park, in-
Cludes land near Red Shirt Lake.
Talkeetna, the only village in the Area, is near the rail-·
road and is also accessible by a State highway. Talkeetna
serves <as a business and social center for the rural popula-
tion and also as a center for many recreational activities,
including fishing, hunting, and mountain climbing.
Except for widely scattered homesteads and cabin sites,
the southern half of the Area 'and a large part west of the
Susitna River are essentially unsettled. A few dirt roads
lead into these areas, but they are not maintained and
generally are not suitable for passenger cars.
Most of the roads and many of the trails were con-
structed as a result of intensive oil explorations, especially
in the southern half of the Area. Most of the drilling ac-
tivities and all of the presently producing oilwells, how-
ever, are outside the survey area.
Literature Cited
(1) AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS.
1961. STANDARD SPECIFICATIONS FOR HIGHWAY MATERIALS AND
METHODS OF SAMPLING AND TESTING. Ed. 8, 2 V.,
ill us.
(2) BALDWIN, MARK, KELLOGG, CHARLES, E., AND THORP, JAMES.
1938. SOIL CLASSIFICATION. Soils and Men, U.S. Dept. Agr.
Ybk.: 970-1001, illus.
(3) CAPPS, STEPHEN R.
1940. GEOLOGY OF THE ALASKA RAILROAD REGION. U.S. Geo-
logical Survey, Bul. 907. 201 pp., ill us.
( 4) F ARR, WILBUR A.
1967. GROWTH AND YIELD OF WELL-STOCKED WHITE SPRUCE
STANDS IN ALASKA. U.S. Forest Service Research
Paper PNW-53, 30 pp.
(5) FREEMAN, MERVIN L.
1967. LAND AND LIVING IN ALASKA. Cooperative Extension
Service, University of Alaska, Pub. No. 54, 16 pp.,
ill us.
(6) GREGORY, ROBERTA., AND HAAcK, PAUL M.
1965. GROWTH AND YIELD OF WELL-STOCKED ASPEN AND BIRCH
STANDS IN ALASKA. U.S. Forest Service Research
Paper Nor-2, 1965,28 pp., illus.
(7) HANSON, HERBERT C.
1951. CHARACTERISTICS OF SOME GRASSLAND, MARSH, AND
OTHER PLANT COMMUNITIES IN WESTERN ALASKA.
Ecological Monographs 21: 317-378.
(8) HUTCHINSON, KEITH 0.
1967. ALASKA'S FOREST RESOURCE. Institute of Northern
Forestry, Juneau, Alaska. U.S. Forest Service Re-
source Bul. PNW-19, 74 pp., illus.
(9) KARLSTROM, THOR N. V.
1953. UPPER COOK INLET REGION, ALASKA. U.S. Geological
Survey Cir. 289, pp. 3-5.
(10) KELLOGG, CHARLES E. AND NYGARD, IVER J.
1951. EXPLORATORY STUDY OF THE PRINCIPAL SOIL GROUPS OF
ALASKA. U.S. Dept. Agr. Mono. No. 7, 138 pp., illus.
(11) LAUGHLIN, W. M., TAYLOR, R. L., KLEBESADEL, L. J., AND
OTHERS.
1964. GENERAL RECOMMENDATIONS-FERTILIZERS FOR ALASKA.
Alaska Agr. Expt. Sta. Cir. No. 13, Revised.
(12) LUTZ, H. J.
1956. ECOLOGICAL EFFECTS OF FOREST FIRES IN THE INTERIOR OF
ALASKA. U.S. Dept. Agr. Tech. Bul. No. 1133, 121
pp., illus.
(13) MASSIE, MICHAEL R. C.
1966. MARKETING HARDWOODS FROM ALASKA'S SUSITNA
VALLEY. Institute of Social, Economic, and Gov-
ernment Research, University of Alaska, SEG
Report No. 9; 162 pp., ill us.
(14) RHODES, C. J. AND BARKER, W.
1953. ALASKA'S FISH AND WII,DLIFE. Fish <and Wildlife
Service, U.S. Dept. Int. Cir. 17, 60 pp., illus. ·
( 15) RIEGER, SAMUEL AND DEMENT, JAMES A.
1965. CRYORTHODS OF THE COOK INLET-SUSITNA LOWLAND,
ALASKA. Soil Sci. Soc. Amer. Proc., v. 29: 448-
453.
(16) RIEGER, SAMUEL AND JUVE, ROBERT L.
1961. SOIL DEVELOPMENT IN RECENT LOESS IN THE MATANUSKA
VALLEY, ALASKA. Soil Sci. Soc. Amer. Proc., v. 25:
243-248.
(17) SIMONSON, ROY W.
1963. SOIL CONSERVATION AND THE NEW CLASSIFICATION SYS-
TEM. Soil Sci. 96: 23-30.
(18) SKOW, DUANE.
1967. ALASKA AGRICULTURAL STATISTICS-1966. Alaska
Crop and Livestock Reporting Service. 23 pp., illus.
(19) THORP, JAMES AND SMITH, GUY D.
1949. HIGHER CATEGORIES OF SOIL CLASSIFICATION: ORDER,
SUBORDER, AND GREAT GROUPS. Soil Sci. 67: 117-
126, illus.
(20) UNITED STATES DEPARTMENT OF AGRICULTURE.
(21)
1951. SOIL SURVEY MANUAL. Agr. Handb. No. 18, 503 pp.,·
ill us.
1960. SOIL CLASSIFICATION, A COMPREHENSIVE SYSTEM, 7TH
APPROXIMATION. 265 pp., ill us. [Supplements issued
in March 1967 and September 1968]
(22) UNITED STATES DEPARTMENT OF DEFENSE.
1968. UNIFIED SOIL CLASSIFICATION SYSTEM FOR ROADS, AIR-
FIELDS, EMBANKMENTS AND FOUNDATIONS. MIL-
STD-619B, 30 pp., ill us.
(23) U.S. FOREST SERVICE, INSTITUTE OF NORTHERN FORESTRY.
1966. PRELIMINARY FOREST SURVEY STATISTICS FOR THE
SUSITNA RIVER VALLEY, ALASKA, 1965.
(24) WAHRHAFTIG, CLYDE.
1965. PHYSIOGRAPHIC DIVISIONS OF ALASKA. U.S. Geological
Survey Prof. Paper 482, 51 pp., ill us.
Glossary
Alluvium. Soil material, such as sand, silt, or clay, that has been
deposited on land by streams.
70 SOlL SURVEY
Available water capacity (also termed available moisture capacity).
The capacity of soils to hold water available for use by most
plants. It is commonly defined as the difference between the
amount of soil water at field capacity and the amount at wilting
point. It is commonly expressed as inches of water per inch
of soil.
Clay. As a soil separate, the mineral soil particles less than 0.002
millimeter in diameter. As a soil textural class, soil material
that is 40 percent or more clay, less than 45 percent sand,
and less than 40 percent silt.
Concretions. Grains, pellets, or nodules of various sizes, shapes,
and colors consisting of concentrations of compounds, or of
soil grains cemented together. The composition of some con-
cretions is unlike that of the surrounding soil. Calcium car-
bonate and iron oxide are examples of material commonly
found in concretions.
Consistence, soil. The feel of the soil and the ease with which a
lump can be crushed by the fingers. Terms commonly used to
describe consistence are--
Loose.-Noncoherent when dry or moist; does not hold together
in a mass.
Friable.-When moist, crushes easily under gentle pressure be-
tween thumb and forefinger and can be pressed together into
a lump.
·Firm.-When moist, crushes under moderate pressure between
thumb and forefinger, but resistance is distinctly noticeable.
Plastic.-When wet, readily deformed by moderate pressure but
can be pressed into a lump ; will fo))m a "wire" when rolled
between thumb and forefinger.
Sticky.-When wet, adheres to other material, and tends to
stretch somewhat and pull apart, rather than to pull free
from other material.
Hard.-When dry, moderately resistant to pressure; can be
broken with difficulty between thumb and forefinger.
Soft.-When dry, breaks into powder or individual grains under
very slight pressure.
O~nted.-Hard and brittle; little affected by moistening.
Dramage class (natural). Refers to the conditions of frequency and
duration of periods of saturation or partial saturation that
existed during the development of the soil, as opposed to altered
drainage, which is commonly the result of artificial drainage
or irrigation but may be caused by the sudden deepening of
channels or the blocking of drainage outlets. Seven different
classes of natural soil drainage are recognized.
Excessively drained soils are commonly very porous and rapidly
permeable and have a low water-holding capacity.
Somewhat ecccessiveZy drained soils are also very permeable and
are free from mottling throughout their profile.
WeZZ-drainea soils are nearly free from mottling and are com-
monly of intermediate texture.
Moderately weZZ arainea soils commonly have a slowly permeable
layer in or immediately beneath the solum. They have uni-
form color in the A and upper B horizons and have mottling
in the lower B and the C horizons.
Somewhat poorly arainea soils are wet for significant periods
but not all the time, and some soils commonly have mottling
at a depth below 6 to 16 inches.
Poorly drained, soils are wet for long periods and are light gray
and generally mottled from the surface downward, although
mottling may be absent or nearly so in some soils.
Very poorly arainea soils are wet nearly all the time. They have
a dark-gray or black surface layer and are gray or light
gray, with or without mottling, in the deeper parts of the
profile.
Erosion. The wearing away of the land surface by wind (sand-
blast), running water, and other geological agents.
Fertility, soil. The quality of a soil that enables it to provide com-
pounds, in adequate amounts and in proper balance, for the
growth of specified plants, when other growth factors such as
light, moisture, temperature, and the physical condition of
the soil are favorable.
Flood plain. Nearly levelland, consisting of stream sediments, that
borders a stream and is subject to flooding unless protected
artificially.
Glacial till (geology). Unassorted, nonstratiiD.ed glacial drift con-
sisting of clay, silt, sand, and boulders transported and de-
posited by ghteial ice.
Horizon, soil. A layer of soil, approximately parallel to the surface,
that has distinct characteristics produced by soil-forming
processes. These are the major horizons:
0 horizon.-The layer of organic matter on the surface of a
mineral soil. This layer consists of decaying plant residues.
A. horizon.-----,The mineral horizon at the surface or just below
an 0 horizon. This horizon is the one in which living
organisms are most active and therefore is marked by the
accumulation of humus. The horizon may have lost one or
more of soluble salts, clay, and sesquioxides (iron and
aluminum oxides).
B horizon.-The mineral horizon below an A horizon. The B
horizon is in part a layer of change from the overlying A to
the underlying C horizon. The B horizon also has distinctive
characteristics caused (1) by accumulation of clay, sesqui-
oxides, humus, or some combination of these; (2) by pris-
matic or blocky structure; (3) by redder or stronger colors
than the A horizon; or ( 4) by some combination of these.
Combined A and B horizons are usually called the solum, or
true soil. If a soil lacks a B horizon, the A horizon alone is
the solum.
a horizon.-The weathered rock material immediately beneath
the solum. In most soils this material is presumed to be like
that from which the overlying horizons were formed. If the
material is known to be different from that in the solum, a
Roma;n numeral precedes the letter C.
R layer.-Consolidated rock beneath the soil. The rock usually
underlies a C horizon but may be immediately beneath an
A or B horizon.
Loess. l!'ine-grained material, dominantly of silt-sized particles,
that has been deposited by wind.
Mottling, soil. Irregularly marked with spots of different colors
that vary in number and size. Mottling in soils usually indicates
poor aeration and lack of drainage. Descriptive terms are as
follows: Abundance--few, aomnnon, and many; size-ji1w,
medium, and coarse; and contrast-faint, distinct, and prom-
inent. The size measurements are these : fine, less than 5 milli-
meters (about 0.2 inch) in diameter along the greatest
dimension; medium, ranging from 5 millimeters to 15 milli-
meters (about 0.2. to 0.6 inch) in diameter along the greatest
dimension; aiJJd coarse, more than 15 millimeters (about 0.6
inch) in diameter along the greatest dimension.
Munsell notation. A system for designating color by degrees of the
three simple variables-hue, value, and chroma. For example,
a notation of 10YR 6/4 is a color with a hue of 10YR, a value
of 6, and a chr&:na of 4.
Nutrient, plant. Any element taken in by a plant, essential to its
growth, and used by it in the production of food and tissue.
Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur,
iron, manganese, copper, boron, zinc and other elements
obtained from the soil and carbon, hydrogen, and oxygen,
obtained largely from the air and water, are plant nutrients.
Parent materal. Disintegrated and partly weathered rock from
which soil has formed.
Permeability. The quality that enables the soil to transmit water
or air. Terms used to describe permeability are as follows:
very slow, slow, moderately slow, moderate, moderately rapid,
rapid, and very rapid.
pH value. A numerical means for designating acidity and alkalinity
in soils. A pH value of 7.0 indicates precise neutrality; a higher
value, alkalinity; and a lower value, acidity.
Reac~ion, soil. The degree of acidity or alkalinity of a soil, expressed
m pH values. A soil that tests to pH 7.0 is precisely neutral in
reaction because it is neither acid nor alkaline. An acid, or
"sour," soil is one that gives an acid reaction; an alkaline
soil is one that is alkaline in reaction. In words, the degrees
of acidity or alkalinity are .expressed thus :
Extremely acid--
Very strongly
acid.
Strongly acid ___ _
Medium acid ____ _
Slightly acid ____ _
pH
Below 4.5
4.5 to 5.0
5.1 to 5.5
5.6 to 6.0
6.1 to 6.5
Neutral ---------Mildly alkaline __
Moderately alka-
line.
Strongly alkaline_
Very strongly
alkaline.
pH
6.6 to 7.3
7.4 to 7.8
7.9 to 8.4
8.5 to 9.0
9.1 and
higher
Relief. Tille elevations or inequalities of a land surface, considered
collectively.
SUSITNA VALLEY AR'EA, AL.A!SKA 71
Runoff. The part of the precipitation upon a drainage •area that is
discharged from the area in stream channels. The water that
:flows off the land surface without sinking in is called surface
runoff; that which enters the soil before reaching surface
streams is called ground-water runoff or seepage flow from
ground water.
Sand. Individual rock or mineral fragments in a soil that range in
diameter from 0.05 to 2.0 millimeters. Most sand grains consist
of quartz, but they may be of any mineral composition. The
textural class name of any soil that contains 85 percent or more
sand and not more than 10 percent clay.
Sequum. A sequence consisting of an illuvial B horizon and the
overlying eluvial A horizon. If two sequa are present in a
single soil profile, it is said to have a bisequum.
Silt. Individual mineral particles in a soil that range in diameter
from the upper limit of clay (0.002 millimeter) to the lower
limit of very fine sand (0.05 millimeter). Soil of the silt tex-
tural class is 80 percent or more silt and less than 12 percent
clay.
Soil. A natural, three-dimensional formation on the surface of the
earth 1Jhat supports pl:ants and that has properties resulting
from the combined effect of climate and living matter acting on
earthy parent material, as conditioned by relief over periods
of time.
Soil separates. Mineral particles, less than 2 millimeters in equiv-
alent diameter and ranging between specified size limits. The
names and sizes of separates recognized in the United States
are as follows: Very coarse sana (2.0 to 1.0 millimeter) ; coarse
sana (1.0 to 0.5 millimeter) ; medium sana (0.5 to 0.25 milli-
meter) ; fine sana (0.25 to 0.10 millimeter) ; very fine sana
(0.10 to 0.05 millimeter) ; silt (0.05 to 0.002 millimeter) ; and
clay (less than 0.002 millimeter). The separates recognized by
the International Society of Soil Science are as follows: I (2.0
to 0.2 millimeters) ; II (0.2 to 0.02 millimeter); III (0.02 to
0.002 millimeter) ; IV (less than 0. 002 millimeter) .
Structure, soil. The arrangement of primary soil particles into
compound particles or clusters that are separated from ad-
joining aggregates and have properties unlike those of an
equal mass of unaggregated primary soil particles. The prin-
cipal forms of soil structure are-platy (laminated), pris-
matic (vertical axis of aggregates longer than horizontal),
columnar (prisms with rounded tops), blocky (angular or sub-
angular), and granular. Structureless soils are either single
grain (each grain by itself, as in dune sand) or massive (the
particles adhering together without any regular cleavage, as
in many claypans and hardpans) .
Subsoil. Technically, the B horizon; roughly, the part of the
solum below plow depth.
Substratum. Technically, the part of the soil below the solum.
Surface soil. The soil ordinarily moved in tillage, or its equivalent
in uncultivated soil, about 5 to 8 inches in thickness. The plowed
layer.
Terrace (geological). An old alluvial plain, ordinarily fiat or un-
dulating, bordering a river, lake, or the sea. Stream terraces
are frequently called second bottoms, as contrasted to flood
plains, and are seldom subject to overflow. Marine terraces
were deposited by the sea and are generally wide.
Texture, soil. The relative proportions of sand, silt, and clay parti-
cles in a mass of soil. The basic textural classes, in order of
increasing proportion of fine particles, are sana, loamy sana,
sanely loam, loam, silt loam, silt, sanely clay loam, clay loam,
silty clay loam, sanely clay, silty clay, and clay. The sand,
loamy sand, and sandy loam classes may be further divided by
specifying "coarse," "fine," or "very fine."
Tilth, soil. The condition of the soil in relation to the growth of
plants, especially soil structure. Good tilth refers to the friable
state and is associated with high noncapillary porosity and
stable, granular structure. A soil in poor tilth is nonfriable,
hard, nonaggregated, and difficult to till.
Water table. The highest part of the soil or underlying rock material
that is wholly saturated with water. In some places an upper,
or perched, water table may be separated from a lower one
by a dry zone.
Described Management group
Map on
symbol Mapping unit page Number Page
20 14 32
21 20 33
21 25 34
21 9 31
21 6 31
21 6 31
21 15 32
21 20 33
22 11 32
22 8 31
22 8 31
22 17 33
22 20 33
22 27 34
23 1 30
23 19 33
23 1 30
24 18 33
24 30 34
24 32 34
25 23 34
25 13 32
25 2 30
26 4 31
26 7 31
26 14 32
26 20 33
•
GUIDE TO MAPPING UNITS
For a full description of a mapping unit, read both the description of the mapping unit and that of the soil
series to which the mapping unit belongs. In referring to a management group, read the introduction to the
subsection it is in for general information about management of the soils. Facts about woodland, wildlife,
and recreation are provided in the subsections beginning on p. 35, p. 37, and p. 39, respectively. Other
information is given in tables as follows:
Acreage and extent, table 1, p. 5.
Estimated yields, table 2, pp. 28-29.
Engineering uses of the soils, tables 5, 6,
and 7, pp. 46 through 61.
Map
symbol Mapping unit
BeF
Ca
Ch
CIA
ClB
ClC
Cn
Co
DeA
DeB
DeC
DeD
Om
Dn
Dr
FhA
FhB
Ga
Gv
HoA
HoB
HoC
HoD
HoE
Ja
Ka
KsA
KsB
KsC
KsD
KsE
KsF
Kr
Lu
Me
~
N~
NaB
NaC
NaD
NaE
NaF
NcA
NcB
NcC
NeD
NeE
Nk
RaA
RaB
RaC
Bernice sandy loam, steep----------------------------------------------
Caswell silt loam------------------------------------------------------
Chena fine sandy loam--------------------------------------------------
Chulitna silt loam, nearly level---------------------------------------
Chulitna silt loam, undulating-----------------------------------------
Chulitna silt loam, rolling--------------------------------------------
Clunie peat------------------------------------------------------------
Coal Creek silt loam---------------------------------------------------
Delyndia silt loam, nearly level---------------------------------------
Delyndia silt loam, undulating----------------------------------~-----
Delyndia silt loam, rolling--------------------------------------------
Delyndia silt loam, hilly----------------------------------------------
Delyndia-Salamatof complex---------------------------------------------
Dinglishna sandy loam--------------------------------------------------
Dinglishna-Moose River complex-----------------------------------------
Flat Horn silt loam, nearly level--------------------------------------
Flat Horn silt loam, undulating----------------------------------------
Gravelly alluvial land-------------------------------------------------
Gravel pits------------------------------------------------------------
Homestead silt loam, nearly level-----------------------------------~-
Homestead silt loam, undulating----------------------------------------
Homestead silt loam, rolling-------------------------------------------
Homestead silt loam, hilly---------------------------------------------
Homestead silt loam, moderately steep-----------------------------,----
Jacobsen very stony silt loam------------------------------------------
Kalifonsky silt loam---------------------------------------------------
Kashwitna silt loam, nearly level--------------------------------------
Kashwitna silt loam, undulating-----------------------------------L ___ _
Kashwitna silt loam, rolling-------------------------------------------
Kashwitna silt loam, hilly---------------------------------------------
Kashwitna silt loam, moderately steep----------------------------------
Kashwitna silt loam, steep---------------------------------------------
Killey-Moose River complex---------------------------------------------
Lucile silt loam-------------------------------------------------------
Mixed alluvial land----------------------------------------------------
Moose River silt loam--------------------------------------------------
Nancy silt loam, nearly level------------------------------------------
Nancy silt loam, undulating--------------------------------------------
Nancy silt loam, rolling-----------------------------------------------
Nancy silt loam, hilly-------------------------------------------------
Nancy silt loam, moderately steep--~----------------------------------
Nancy silt loam, steep-------------------------------------------------
Nancy silt loam, sandy substratum, nearly level------------------------
Nancy silt loam, sandy substratum, undulating--------------------------
Nancy silt loam, sandy substratum, rolling-----------------------------
Nancy silt loam, sandy substratum, hilly-------------------------------
Nancy silt loam, sandy substratum, moderately steep--------------------
Niklason fine sandy lbam-----------------------------------------------
Rabideux silt loam, nearly level---------------------------------------
Rabideux silt loam, undulating-----------------------------------------
Rabid~ilt loam, rolling--------------------------------------------
Described
on
page
6
6
7
8
7
8
8
9
9
10
10
10
10
11
11
11
12
12
12
12
12
13
13
13
13
14
14
14
15
15
15
15
15
16
16
17
17
17
18
18
18
18
18
18
19
19
19
19
20
20
20
Management
Number
26
5
22
2
4
7
27
19
11
8
8
17
27
24
24
1
3
32
31
16
16
16
21
21
28
12
9
6
6
15
20
25
18
9
29
24
2
4
7
14
20
25
2
4
7
14
20
10
2
4
7
group
Page
34
31
33
30
31
31
34
33
32
31
31
33
34
34
34
30
30
34
34
32
32
32
33
33
34
32
31
31
31
32
33
34
33
31
34
34
30
31
31
32
33
34
30
31
31
32
33
32
30
31
31
150° 10'
I
T. 27 N.
150 ° 20'
I J
T. 26 N.
T. 25 N.
T. 23 N.
T. 22 N.
T . 21 N.
T. 20 N.
R. 4 W.
T. 19 N.
-61°40'
T. 18 N.
T. 17 N.
-61 °30'
-61 °20'
T. 14 N.
T. 13 N. R. 7 W. R. 6 W. R. 5 W.
-...
-62°20'
-62°10'
•
-62°00'
-61 ·so•
SOIL ASSOCIATIONS*
Rabideux -Sa la matof associati o n: Dom i nant l y nearly
l evel to steep, well -drained s ilt l ooms that are shal l ow
and m oderately deep ove r s and o r g r ave ll y sond and are
on up lands ; and nearl y l eve l , ve r y poorly drained, fibrous
peats in muskegs
Nancy-Kashwitna as soc ia tion: Dom inantly nearly level
t o steep, we ll-drained s ilt l ooms that are mode r ately
d eep and sha ll ow ove r sand o r g r ave ll y sa nd; on up l ands
Nancy-De l yndia as soc iat i o n: D om inantl y n e arly lev e l
t o steep, we 11-dra i ned and so mewhat excess iv e ly drained
s ilt l ooms that are moderate l y deep and shall ow over
s and o r g r ave II y s and; on up l ands
Kashwitna-H omestead ass oc iati on: Dominantly nearl y
I eve I to steep, we 11-dra ined s i It looms that are sha I l ow
and ve r y shall ow ove r g ra ve ll y sand o r g ravelly sandy
l oam ; on uplands
Sus i tna -Schrock associati on : Dominantly near l y l evel,
well-drained, s t rati f ied f i ne sandy l oom s and s il t l ooms
that are deep over sa nd o r gravel l y sand ; on a ll uvial
p lains
C luni e -Tidal Marsh a ssoc i at i o n: D o minantly near l y l eve l,
very poorly dra i ned, fibrous peats and poorly draine d,
c la yey sediment; o n tidal p lai ns
Sa la matof-Ja cobsen ass oc iat i on : Dom i nant l y nearly level,
ve r y poorly drained, fibr ous pe ats i n muskegs ; and nea rly
level, very poor l y drained, ver y stony s ilt l ooms al ong
the edges of muskegs
*Texture named i n so il assoc i at i ons i s that of su rface laye r.
Co mpil ed 1972
N
U. S. DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
UNIVERSITY OF ALASKA INSTITUTE OF AGRICULTURAL SCIENCES
GENERAL SOIL MAP
SUSITNA VALLEY AREA, ALASKA
Scale 1 : 380,160
0 1 2 3 4 5 6 M des
lt~d I I I I I I
This map is for general planning. It shows
only th e major soils and does not contain
s ufficie nt detail for operational planning .
T. 7 N .
• 26 N .
. 23 N.
T . 19 N .
Inset, sheet 24
T. 17 N.
T . 14 N .
T. 13 N. R. 7 W . R. 6W.
-61 °40'
-61 °30'
-61 °20'
R. 5 W.
..
N
INDEX TO MAP SHEETS
SUSITNA VALLEY AREA, ALASKA
Scale 1 : 380,16 0
0 2 3 4 5 6 M des
l,r!l I I I I I
26 N.
T . 21 N.
T. 19 N.
Inset, sheet 24
T . 17 N.
T . 14 N.
T. 13 N . R. 7 W. R. 5 W.
-6 ·0 10'
-61°40'
-61 °30'
-61 °20'
N
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U. S. DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
WORKS AND STRUCTURES
Highways and roads
Di vided ...
Good motor
Poor motor
Trail
Highway markers
N ational Interstate
U.S.
State or county
Railroads
Single track
Multiple track
Abandoned
Bridge s and crossings
Road
Trail
Railroad
Ferry
Ford
Grade
R. R. over
R. R. under
Buildings
School
Church
Min e and quarry
Gravel pit
Power line
Pipeline
Cemetery
Dams
Levee
Tank s
Well, oil or gas ..
Forest fire o r lookou t statio n
Windmill ...................... .
L ocated object
v
0
0
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======~FYi======
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0
CONVENTIONAL SIGNS
BOUNDARIES
National or state
County
Limit of soil survey
Reservation
Land grant
Small park, cemetery, airport
Land survey division corners L _L + ~
DRAINAGE
Streams. double-line
Perennial
Interm ittent
Streams, single-line
Perennial .....
Intermittent
Crossable with tillage
implements
Not crossable with tillage
implements
Unclassified
Canals and ditches
Lakes and ponds
Perennial ......•.
Intermittent
Spring
Marsh or swamp
Wet spot ..
Drainage end or alluv ia l fan
Escarpments
Bedrock
Other
Short steep slope
Prominent peak
Depressions
Crossable with tillage
implements
RELIEF
Not crossable with tillage
implements
Contains water most of
the time ................... .
-:;:::.::. -. :··--... ·--·---... ·--
__..-·---.... .----·-·--
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___.----· .. _ .. / ··-
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·-·-·-·
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Large Small
;~:~·:;~ 0
SUSITNA VALLEY AREA, ALASKA
SOIL SURVEY DATA
Soil boundary
and symbol
Gravel
{
Stony .....
Stoniness
Very stony
Rock outcrops ..
Chert fragments
Clay spot
Sand spot
Gumbo or scabby spot
Made land
Severely eroded spot
Blowout, wind erosion
Gully ......................... ..
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SYMBOL
BeF
Ca
Ch
C IA
C IB
CIC
Cn
Ca
De A
DeB
DeC
DeD
Dm
Dn
Dr
FhA
FhB
Ga
Gv
HaA
HaB
HaC
HaD
HaE
Ja
Ka
KsA
KsB
KsC
KsD
KsE
KsF
Kr
Lu
Me
UNIVERSITY OF ALASKA INSTITUTE OF AGRICULTURAL SCIENCES
SOIL LEGEND
The first capitol letter is the initial one of the soil nome. A second capito l letter,
A, B, C, D, E, or F, shows the slope. Most symbols without a slope letter are
those of nearly level soils, but some a re for land types that hove a considerable
range of slope.
NAME
Bern ice sandy loom, steep
Caswe ll silt loam
Chene f ine sandy loom
C hulitna silt loom, nearly leve l
Chulitna silt loom, undulating
Chu litna silt loam, rolling
Clunie peat
Coal C reek silt loom
De lyndio silt loom, nearly level
Delyndia silt loom, undulating
Delyndia s il t loam, rolling
De lyndia s ilt loam1 hi ll y
Delyndia-Sa !amatof complex
Dinglishno sandy loom
Dinglishna-Moose River complex
Flat Horn silt loam, nearly level
F lot Horn s i It loam, undu loti ng
Grave ll y alluvial land
Grovel pits
Homestead silt loom, nearly level
Homestead s i It loom, undulating
Homestead silt loam, rolling
Homestead silt loam, hilly
Homestead silt loam, moderately steep
Jacobsen very stony s ilt loom
Kolifonsky silt loom
Koshwitno silt loom , nearly level
Kashwitno s i It loom, undulating
Koshwitno silt loam, rolling
Kashwitno silt loam, hilly
Kashwitna si It loam, moderately steep
Koshwitna s i It loom, steep
Ki I ley-Moose River complex
Lucile s ilt loom
Mixed alluvial land
SYMBOL
RaA
RaB
RaC
RaD
RaE
RaF
RbA
RbB
RbC
RbD
RbE
RdA
RdB
RdC
RdD
RdE
Sa
ShA
Sm
Ss
Sw
Te
Tf
Tm
Wa
WhA
WhB
WhC
WhD
WhE
NAME
Rabideux silt loam, nearl y level
Rabideux s ilt loam, undulating
Rabideux s i lt loam, rolling
'Rabideux silt loom, hilly
Rabideux sil t loam, moderately steep
Rabideux si It loom, steep
Robideux s ilt loom , shallow, nearly level
Rabideux s ilt loam, shallow, undulating
Rabideux s ilt loom, shallow, roll ing
Rabideux s ilt loam, shallow, hilly
Rabideux s ilt loam, shallow, moderately steep
Robideux si It loam, sandy substratum, nearly level
Rab ideux si It loam, sandy substratum, undulating
Rabideux si lt loam, sandy substratum, rolling
Rabideux si It loam, sandy substratum, hilly
Robideux si It loom, sandy substratum, moderately
steep
So lamotof peat
Schrock silt loom, nearly level
Sl ikok mucky silt loo m
Sus itna fine sandy loom
Susitno and Niklason fine sandy looms, overflow
T erroce escarpments
Tidal flats
Tidal marsh
Wasilla si lt loom
Whitsel si lt loam, nearly level
Whitse l si lt loam, undulating
Wh itsel s ilt loam, ro lling
Whitsel si lt loam, hilly
Whitsel s ilt loom, moderately steep
Mr Moose River silt loam
NaA
NaB
NaC
NaD
NaE
NaF
NcA
NcB
NcC
NeD
NeE
Nk
Nancy si lt loam, nearly level
Nancy s ilt loam, undulating
Nancy s ilt loam, rolling
Nancy s i It loam, hi l ly
Nancy s i It loam, moderately steep
Nancy si lt loom, steep
Nancy s ilt loam, sandy substratum, nearly level
Nancy s i It loam, sandy substratum, undulating
Nancy silt loom, sandy substratum, rolling
Nancy silt loom, sandy substratum, hilly
Nancy si lt loam, sandy substratum, moderately
steep
Nik lo son fine sandy loam
T. 7 N .
li 26 N.
24 N.
T. 21 N.
T. 19 N.
Inset, sheet 24
T . 17 N.
T. 14 N.
T. 13 K R. 7 W. R. 6 W.
150"01D'
I
-6 "10'
-61"40'
-61 "30'
R. 5 W.
....--,--,-
N
INDEX TO MAP SHEETS
SUSITNA VALLEY AREA, ALASKA
Scale 1:380,160
0 1 2 3 4 5 6 Mdes
1,1!1 I I I I I I