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
Dravo Gravel Site Dravo. The inhabitants' technology prompted their classification as a people of the middle of the Late Archaic Period. In 1978, the Dravo site was listed on the National Register of Historic Places, qualifying because of its archaeological significance. Dravo Gravel Site The Dravo Gravel Site (33HA377) is an archaeological site located above the Great Miami River in Miami Township, Hamilton County, Ohio, United States. Discovered in the middle of a gravel pit, the site is a leading example of the local manifestation of the Archaic period. The site lies atop a Miami River terrace outside the village of Cleves, occupying