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
Gravel Run (Susquehanna River tributary) the United States Geological Survey quadrangle of Riverside. The stream is one of the main streams in Northumberland County. Gravel Run has been contained in Northumberland County since the county was formed in 1772, when Pennsylvania was still a colony. At the time, it was located in Augusta Township, but in 1785, Catawissa Township split off from Augusta, with Gravel Run part of the border between the two. Three years later, in 1788, Ralpho Township split from Catawissa, and included the land that bordered Augusta; Ralpho was renamed Shamokin a year later. In 1819, Rush Township was created by splitting