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Unified Soil Classification System (USCS) <br /> MAJOR DIVISIONS BOL TYPICAL DESCRIPTION <br /> i W GW <br /> Clean Gravels 4 Well-graded gravels,gravels,gravel-sand mixtures,little or no fines <br /> Gravels (less than 5% Gp <br /> (more than 50% fines) Poorly graded gravels,gravel-sand mixtures,little or no fines <br /> of coarse fractionIli GM <br /> retained on No.4 Gravels with '= Siltygravels,gravel-sand-silt mixtures <br /> COARSE sieve) Fines <br /> el <br /> GRAINED (more than 12% ;,;d; GC <br /> SOILS <br /> fines) 1 Clayey gravels,gravel-sand-clay mixtures <br /> (more than 50% :-: sW <br /> retained on Clean Sands Well-graded sands,gravelly sands,little or no fines <br /> No.200 sieve) Sands (less than 5% sp <br /> (50%or more fines) Poorly graded sand,gravelly sands,little or no fines <br /> of coarse fraction <br /> passes the No.4 Sands with 0 sM <br /> - Silty sands,sand-silt mixtures <br /> sieve) Fines <br /> (more than 12% sc <br /> fines) Clayey sands,sand-clay mixtures <br /> ML Inorganic silts of low to medium plasticity,sandy silts,gravelly silts, <br /> or clayey silts with slight plasticity <br /> Silts and Clays Inorganic CL Inorganic clays of low to mediumplasticity,gravellyclays,sandyclays <br /> (liquid limit less g y y' y <br /> FINE GRAINED than 50) silty clays,lean clays <br /> SOILS OL <br /> Organic Organic silts and organic silty clays of low plasticity <br /> (50%or more <br /> passes the MH Inorganic silts,micaceous or diatomaceous fine sands or silty soils, <br /> No.200 sieve) elastic silt <br /> Silts and Clays Inorganic CH <br /> (liquid limit 50 or Inorganic clays of medium to high plasticity,sandy fat clay, <br /> more) or gravelly fat clay <br /> OH <br /> Organic Organic clays of medium to high plasticity,organic silts <br /> HIGHLY ORGANIC Primarily organic matter,dark in color, PT <br /> SOILS and organic odor Peat,humus,swamp soils with high organic content(ASTM D4427) <br /> Classification of Soil Constituents <br /> Grain Size Definitions <br /> Description Sieve Number and/or Size <br /> MAJOR constituents compose more than 5o percent, Fines <#200(0.08 mm) <br /> by weight,of the soil. Major constituents are capitalized Sand <br /> (i.e.,SAND). <br /> -Fine #200 to#40(o.o8 to 0.4 mm) <br /> Minor constituents compose 12 to 5o percent of the soil -Medium #40 to#10(0.4 to 2 mm) <br /> and precede the major constituents(i.e.,silty SAND). -Coarse #10 to#4(2 to 5 mm) <br /> Minor constituents preceded by"slightly"compose Gravel <br /> 5 to 12 percent of the soil(i.e.,slightly silty SAND). -Fine #4 to 3/4 inch(5 to 19 mm) <br /> Trace constituents compose o to 5 percent of the soil -Coarse 3/4 to 3 inches(19 to 76 mm) <br /> (i.e.,slightly silty SAND,trace gravel). <br /> Cobbles 3 to 12 inches(75 to 305 mm) <br /> Boulders >12 inches(305 mm) <br /> Relative Density Consistency <br /> (Coarse Grained Soils) (Fine Grained Soils) <br /> N,SPT, Relative N,SPT, Relative <br /> Moisture Content Definitions <br /> Blows/FT Density Blows/FT Consistency <br /> 0-4 Very loose Under 2 Very soft <br /> 4-10 Loose 2-4 Soft Dry Absence of moisture,dusty,dry to the touch <br /> 10-30 Medium dense 4-8 Medium stiff <br /> 3o-5o Dense 8-15 Stiff Moist Damp but no visible water <br /> Over 5o Very dense 15-3o Very stiff <br /> Over 3o Hard Wet Visible free water,from below water table <br /> Cobalt Geosciences,LLC <br /> P.O.Box 82243 <br /> ;.. Kenmore,WA 98028 Soil Classification Chart Figure C1 <br /> ~- (206)331-1097 <br /> COBALT www.cobaltgeo.com <br /> GEOSCIENCES cobaltgeo0gmail.com <br />