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).
Eye Gravel Pit no public access. Eye Gravel Pit Eye Gravel Pit is a 0.4 hectare geological Site of Special Scientific Interest in Eye Green in Cambridgeshire. It is a Geological Conservation Review site, and part of it overlaps Eye Green Local Nature Reserve. This former gravel quarry in the East Anglian Fens has marine and a few non-marine shells laid down when the area was under the North Sea, probably during the warm Eemian period, 130,000 to 115,000 years ago. It is described by Natural England as important because it lies at the junction between fluvial and glacial deposits. The site is