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UNIFIED SOIL CLASSIFICATION SYSTEM Major Group Typical Field Identification Procedures Information Required for i Divisions Symbols Names {excluding particles larger than 3 Inches Describing Soils and basing fractions on estimated weights) i 2 3 4 5 6 m GW Well-graded gravels,gravel-sand mixtures,little or Wide range in grain sizes and substantial amounts of For undisturbed soils add information on no fines. all intermediate particle sizes. stratification,degree of compactness,cementation, .a g moisture conditions,and drainage characteristics. .. GP Poorly graded gravels or gravel-sand mixtures,little Predominantly one size or a range of sizes wilh some Of no fines. Olermediate sizes missing. [7 m GM Silty gravels,gravel-sand-silt mixture. Nonplastic lines Or fines with low plasticity Give typical name: Indicate approximate e• (tor identification procedures see ML below) percentage sand and gravel,maximum size; e angularity,surface condition,and hardness of the m 'e LL m ° GC Clayey gravels,gravel sand-clay mixtures. Plastic fines(for identification see CL below) coarse grains;local or geologic name and other �d 7a pertinent descriptive information;and symbol in 9I _ SW Well-graded sands•gravelly sands,little or no Wide range in grain size and substantial amounts of parentheses. R m fines. all intermediate particle sizes. g = g SP Poorly graded sands or gravelly sands,little or no Predominantly one size or a range of sizes with some Example: a 3 lines, intermediate sizes missing. Silty s9nd,gravelly;about 20%hard,angular ? gravel particles 112 in.maximum size;rounded and SM Silty sands,sand-silt mistures. Nonplastic fines or lines with low plasticity subangular sand grains,course to fine;about 15% m (for ideotification procedures see ML below) nonplastic fines with low dry strength;well compacted and moist In place;alluvial sand;(SM). SC Clayey sands,sand-clay mixtures. Plastic fines (for identification procedures see CL ,g below) Identification Procedures on Fraction Smaller than No.40 Sieve Size Dry Strength Dilatancy Toughness (Crushing (Reaction (Consistency characteristics) to shaking) near PLf ML Inorganic silts and very line sands,rock flour,silty None to slight Ouick to slow None For undisturbed soils add information on structure, c 'or clayey'line sands or clayey silts with slight strat1ication,consistency In undisturbed and U e plasticity, remolded states,moisture and drainage conditions. CL Inorganic clays of low to medium plasticity,gravelly Medium to Nona 10 very Medium clays,sandy clays,silty clays,lean clays. high slow tZ .`l OL Organic silts and organic silly clays of low Slight to Siow Slight Give typical name;indicate degree and character LL plasticity, medium of plasticity;amount and maximum size of coarse grains;color in wet condition;odor,if any;total or o MH Inorganic sills,micaceous or diatomaceous line Slight to Srow to none Slight to geologic name and other pertinent descriptive sandy or silty soils,elastic silts. medium medium information;and symbol in parentheses. m CH Inorganic clays of high plasticity,lot clays. High to None High very high - OH Organic clays and silts of medium to high plasticity. Medium to Nona to Slight to Example: high vary slow medium Clavev sill,brown;slightly plastic;small percentage of fine sand;numerous vartical root holes;firm and Highly Organic Soils Pt Peat and other highly organic soils. Readily Identified by color,odor,spongy feel and dry in plata;loess;(ML). frequently by fibrous texture. Roux ASS MATH G i