Unified Soil Classification System group symbol. For example, GW-GM corresponds to "well-graded gravel "with silt"." If the soil has more than 15% by weight retained on a #4 sieve (R > 15%), there is a significant amount of gravel, and the suffix "with gravel" may be added to the group name, but the group symbol does not change. For example, SP-SM could refer to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel." Unified Soil Classification System The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size
Natchez silt loam the bluff hills that border the Mississippi Delta floodplains. They formed in silty loess material that ranges from strongly acid to neutral in the upper part and neutral to slightly alkaline in lower parts. Average annual precipitation is 52 inches. Average annual air temperature is 63 °F (17 °C). The soil has developed in the upper Pleistocene age material. Natchez silt loam In 1988, the Professional Soil Classifiers Association of Mississippi selected Natchez silt loam soil to represent the soil resources of the State. These soils exist on 171,559 acres (0.56% of state) of landscape in Mississippi. The Natchez Silt