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).
Granular dogfish Granular dogfish The granular dogfish, "Centroscyllium granulatum", is a little-known, very small dogfish shark of the family Etmopteridae, endemic to the Falkland Islands. The granular dogfish has no anal fin, two dorsal spines with the second one much larger than the first, a large second dorsal fin, a long abdomen, small pectoral and pelvic fins, a large eye, prominent nostrils and spiracles, and brownish-black coloration. It is very small, growing to only 28 cm. They have only been found around the Falkland Islands in the South Atlantic. Almost nothing is known about this shark. It has been caught at around