Environmental Engineering Reference
In-Depth Information
TABLE 7.2
Distribution of Principal Soil Deposits in the United States
Origin of
Symbol
Physiographic
Physiographic Features
Characteristic Soil
Principal
for Area
Province
Deposits
Soil Deposits
in
Figure 7.1
Alluvial
Al
Coastal plain
Terraced or belted
Marine and continental
coastal plain with
alluvium thickening
submerged border on
seaward. Organic soils
Atlantic. Marine plain
on coast. Broad clay
with sinks, swamps, and
belts west of Mississippi.
sand hills in Florida
Calcareous sediments on
soft and cavitated
limestone in Florida
Alluvial
A2
Mississippi
River floodplain and
Recent alluvium, fine
alluvial plain
delta
grained and organic in
low areas, overlying
clays of coastal plain
Alluvial
A3
High Plains
Broad intervalley
Outwash mantle of silt,
section of Great
remnants of smooth
sand, silty clay, lesser
Plains province
fluvial plains
gravels, underlain by
soft shale, sandstone,
and marls
Alluvial
A4
Basin and range
Isolated ranges of
Desert plains formed
province
dissected block
principally of alluvial
mountains separated by
fans of coarse-grained
desert plains
soils merging to playa
lake deposits. Numerous
nonsoil areas
Alluvial
A5
Major lakes of
Intermontane
Lacustrine silts and clays
basin and range
Pleistocene lakes in
with beach sands on
province
Utah and Nevada,
periphery. Widespread
Salton Basin in
sand areas in Salton
California
basin
Alluvial
A6
Valleys and basins
Intermontane lowlands,
Valley fills of various
of Pacific border
Central Valley,
gradations, fine grained
province
Los Angeles Basin,
and sometimes organic
Willamette Valley
in lowest areas near
drainage system
Residual
R1
Piedmont
Dissected peneplain
Soils weathered in place
province
with moderate relief.
from metamorphic and
Ridges on stronger
intrusive rocks (except
rocks
red shale and sandstone
in New Jersey). Generally
more clayey at surface
Residual
R2
Valley and ridge
Folded strong and weak
Soils in valleys weathered
province
strata forming
from shale, sandstone,
successive ridges and
and limestone. Soil thin
valleys
or absent on ridges
Residual
R3
Interior low
Mature, dissected
Soils weathered in place
plateaus and
plateaus of moderate
from shale, sandstone,
Appalachain
relief
and limestone
plateaus
Residual
R4
Ozark plateau,
Plateaus and plains of
Soils weathered in place
Ouachita,
moderate relief, folded
from sandstone and
province portions
strong and weak
limestone predominantly,
of Great Plains and
strata in Arkansas
Numerous non soil areas
central lowland,
and shales secondarily.
in Arkansas
Wisconsin
driftless section
