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 pugolovka Granular pugolovka The granular pugolovka ("Benthophilus granulosus") is a species of gobiid fish widespread in the Caspian Sea. It is a small fish, with a length up to TL. It was listed as Least Concern by the IUCN in 2008: there are no known major threats. Granular pugolovkas are very abundant in their habitat due to their size and lack of natural predators. The common name 'pugolovka' is a Ukrainian word for tadpole. "Benthophilus granulosus" has a flat head with a flat barbel on the chin that is often described as being leathery. The body colors depend on the habitat