Silt three grades fine, medium and coarse 0.002 mm to 0.006 mm to 0.020 mm to 0.063 mm). In actuality, silt is chemically distinct from clay, and unlike clay, grains of silt are approximately the same size in all dimensions; furthermore, their size ranges overlap. Clays are formed from thin plate-shaped particles held together by electrostatic forces, so present a cohesion. Pure silts are not cohesive. According to the U.S. Department of Agriculture Soil Texture Classification system, the sand–silt distinction is made at the 0.05 mm particle size. The USDA system has been adopted by the Food and Agriculture Organization (FAO).
Campden Tunnel Gravel Pit Midlands and the Upper Thames terraces (Evenlode Valley). The site also links with others in the Moreton-in-Marsh area, for example Stretton-on-Fosse. The site is considered precious so it must only be used for research purposes. Campden Tunnel Gravel Pit Campden Tunnel Gravel Pit () is a geological Site of Special Scientific Interest in Gloucestershire, notified in 1988. The site is listed in the 'Cotswold District' Local Plan 2001-2011 (on line). The site exposes a mixture of gravels, sands and silts which make up the Campden Tunnel Drift (Pleistocene period). These are glacial sediments which fill a deep channel. The melt