Unified Soil Classification System (ASTM D-2487)

SOIL CLASSIFICATION CHARTGroup SymbolGroup Name

COARSE GRAINED SOILMore than 50% retained on No. 200 sieveGravels> 50% retained on No. 4 (4.75 mm) sieveClean GravelsLess than 5% (fines) smaller than No. 200 sieveCU 4; 1 CC 3GWWell graded Gravel

CU < 4; 1 > CC > 3GPPoorly graded Gravel

Gravels w/ FinesMore than 12% finesFines ML or MHGMSilty Gravel

Fines CL or CHGCClayey Gravel

Sands 50% passing on No. 4 (4.75 mm) sieveClean SandsLess than 5% (fines) smaller than No. 200 sieveCU 6; 1 CC 3SWWell graded Sand

CU < 6; 1 > CC > 3SPPoorly graded Sand

Sands w/ FinesMore than 12 % finesFines ML or MHSMSilty Sand

Fines CL or CHSCClayey Sand

FINE GRAINED SOIL50% or more passes No. 200 sieve

Silt and ClayLiquid limit < 50INORGANIC

PI > 7 Plots aboveA lineCLLean Clay

Plots belowA lineMLSilt

ORGANIC

< 0.75OLOrganic Clay/ Organic Silt

Silt and ClayLiquid limit 50INORGANICPlots above A

CHFat Clay

Plots below A

MHElastic Clay

ORGANIC

< 0.75OHOrganic Clay/ Organic Silt