Environmental Engineering Reference
In-Depth Information
TABLE 7.2
(
Continued
)
Origin of
Symbol
Physiographic
Physiographic Features
Characteristic Soil
Principal
for Area
Province
Deposits
Soil Deposits
in
Figure 7.1
section. Varved silt and
clay deposits at Cleveland,
Toledo, Detroit, Chicago,
northwestern Minnesota
Glacial
G3
Areas in southern
Dissected old till plains
Old glacial drift, sorted
central lowland
and unsorted, deeply
weathered, overlying
sedimentary rocks
Glacial
G4
Western area of
Deeply dissected
Varved clay, silt, and sand
northern Rocky
mountain uplands with
in intermontane basins,
Mountains
intermontane basins
overlain in part by coarse-
extensively glaciated
grained glacial outwash
Glacial
G5
Puget trough of
River valley system,
Variety of glacial deposits,
Pacific border
drowned and
generally stratified,
province
glaciated
ranging from clayey silt
to very coarse outwash
Glacial
G6
Alaska peninsula
Folded mountain chains
In valleys and coastal
of great relief with
areas widespread deposits
intermontane basins
of stratified outwash,
extensively glaciated
moraines, and till.
Numerous nonsoil areas
Hawaiian Island
Coral islands on the
Coral islands generally
group
west, volcanic islands
have sand cover. Volcanic
on the east
ash, pumice, and tuff
overlie lava flows and
cones on volcanic islands.
In some areas, volcanic
deposits are deeply
weathered
Nonsoil
Principal
Mountains, canyons,
Locations in which soil
areas
mountain masses
scablands, badlands
cover is very thin or has
little engineering
significance because of
rough topography or
exposed rock
Source
:
Design Manual DM-7, Soil Mechanics, Foundations, and Earth Structures, Naval Facilities Engineering
Command, Alexandria, VA, 1971.
analysis. Classes of drainage patterns in soil formations are described in
Table 7.3,
and the
typical drainage patterns for various soil types and formations are given in
Table 7.4.
Gully characteristics are illustrated in
Figure 7.2.
7.2
Residual Soils
7.2.1
Introduction
General
Residual soils develop
in situ
from the disintegration and decomposition of rock (see
Section 6.7).
The distinction between rock and soil is difficult to make when the transition
