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SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962
Table 7. Unified soil classification system. Corps of Engineers [9]
Major Divisions
Group
Symbool Typical Names
Coarse
grained Soils
More than
half of
material is
larger than
No. 200 sieve
size9
Clean Gravels GW
(Little or no
Gravels fines) GP
More than half
of coarse frac-
tion is larger Gravels with GM
than No. 4 Fines (Appre-
size 2 ) ciable amount GG
of fines)
Well-graded gravels, gravel-sand
mixtures, little or no fines
Poorly graded gravels or gravel-sand
mixtures, little or no fines
Silty gravels, gravel-sand-silt mix
ture
Clayey gravels, gravel-sand-silt
mixtures
Sands
More than half
of coarse frac
tion is smaller
than No. 4
sieve size 2 )
Glean Sands
(Little or no
fines)
Sands with
Fines (Appre
ciable amount
of fines)
SW
SP
SM
SG
Well-graded sands, gravelly sands,
little or no fines
Poorly graded sands or gravelly
sands, little or no fines
Silty sands, sand-silt mixtures
Clayey sands, sand-clay mixtures
Fine-grained
Soils
More than
half of
material is
smaller than
No. 200 sieve
size 9
ML
Silts and Clays CL
Liquid limit is less than 50
OL
Inorganic silts and very fine sands
rock flour, silty or clayey fine sands
or clayey silts with slight plasticity
Inorganic clays of low to medium
plasticity, gravelly clays, sandy clays,
silty clays, lean clays
Organic silts and organic silty clays
of low plasticity
MH
Inorganic silts, micaceous or diato-
maceous fine sandy or silty soils,
Silts and Clays
elastic silts
Liquid limit is greater
CH
Inorganic clays of high plasticity,
than 50
fat clays
OH
Organic clays of medium to high
plasticity, organic silts
Highly Organic Soils Pt Peat and other highly organic soils
9 The Nos. 200 sieve size is about the smallest particle visible to the naked eye.
9 For visual classification, the 1 / 4 -in, size may be used as equivalent to the No. 4 sieve size.
Table 8. Slope classification
S
L
0
P
E
Greater than 16°/ 0
16% to 4%
4% to 0% •
0% to -4%
0о/
U /0
Steep
Gentle
Plane
Depression
Basin
Rolling
Rolling
Undulating
Undulating
Flat
