soil is placed in the groups by performance characteristics. A-1 is the best and A-7 is the worst. A-1 to A-3 are sands and gravels, A-4 to A-7 are silts and clays. There is a A-8 which is reserved for unusable peat. The following is the chart to use to find the designated soil group.

coarse-grained soils are classified as follows: Less than 5 percent ..... GW, GP, SW, SP More than 12 percent ..... GM, GC, SM, SC 5 to 12 percent ..... Borderline cases requiring dual symbols . PLASTICITY CHART . 60 ,,/ ~ ~ 50 ~ CH / / >< 40 . w . V" ALINE: C . Vp1 = on(LL-20)

*For all soil types - Add with "w/Cobbles" if >= 15% Cobbles (3 - 12 inches) **For all soil types - Add with "w/Boulders" if >= 15% Boulders (>12 inches) SILTS & CLAYS (Little or no water

Munsell Soil Color Charts developed by the U.S. Soil Conservation Service classify soil colors and are also used in the classification of natural products such as rocks, archeological specimens, and more.; Grain Size Chart classifies particles in accordance with the Wentworth Grading Scale.Particles are identified in six ranges from silt to very coarse sands.

significant components in the soil. Figure 3-2 is a flow chart for assigning typical names and group symbols for inorganic fine-grained soils; figure 3-3 is a flow chart for organic fine-grained soils; figure 3-4 is a flow chart for coarse-grained soils. Refer to tables 3-1 and 3-2 for the basic group names without modifiers. If