http://www.pjfr.com/blog Wed, 09 Apr 2008 18:29:28 +0000 http://backend.userland.com/rss092 en According to the Unified Soil Classification System (USCS), a soil classification system used in geology and engineering to describe texture and grain size of soil, there are 15 soil types. Well Graded Gravel/Fine to Course Gravel (GW) - Clean gravel with greater than 50% of coarse fraction retained on No. 4 sieve. Poorly ... http://www.pjfr.com/blog/15-soil-types-characteristics