Environmental Engineering Reference
In-Depth Information
interpreted with experience, significant knowledge regarding the engineering characteris-
tics of the formations and materials becomes available.
Preliminary map assessment
permits conclusions regarding:
1.
Abandonment of the site to avoid extremely hazardous conditions
2.
Location of structures to avoid unfavorable conditions
3.
General requirements for foundations and excavation
4.
Formulation of the program of subsurface investigation
Map Preparation
Using a topographic map as a base map, select a scale convenient to the study area and
purpose. Plot the data obtained from terrain analysis including boundaries of the various
soil and rock types, major structural features, areas of shallow groundwater and rock, and
locations of hazards such as sinkholes and landslides. A suggested nomenclature for the
identification of various soil and rock formations is given in Table 2.7.
TABLE 2.7
Suggested Map Symbols for Engineering Geology Maps
Classification
Symbol
Modifiers Based on Coarseness or Occurrence
Residual soil
R
Rm — massive
Rs — saprolite
Rc — coarse-grained (granular)
Rf — fine-grained (clayey or cohesive)
Colluvial soil
C
Cr — originally residual soil
Cm — originally glacio-marine soils
Cl — originally glacio-lacustrine soils
T — talus
Alluvail soil
A
Ao — oxbow lake
At — terrace
Ar — recent alluvium; usually silt-sand mixtures with organic matter
Ac — coarse grained; sand and gravel mixtures
Am — medium grained; sand-silt mixtures
Af — fine grained; silt-clay mixtures
Eolian soil
E
El — loess
Ed — dunes
Glacial soils
G
Gm — moraine
Gt — till
Gs — stratified drift (outwash plains)
Gk — kane
Ge — esker
Gl — lakebed
Organic soils
O
Om — marsh
Os — swamp
Man-made fill
F
High watertable
Hg
Rock symbols
Igneous
Sedimentary
Metamorphic
gr — granite
sg — conglomerate
qz — quartzite
ry — rhyolite
ss — sandstone
ma — marble
sy — syenite
si — siltstone
hr — hornfeld
mo — monzonite
sh — shale
gn — gneiss
di — diorite
ls — limestone
sc — schist
ga — gabbro
ak — arkose
ph — phyllite
ba — basalt
do — dolomite
sl — slate
