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).
Gravel chub type of habitat, increasing the turbidity of the current and the amount of silt in rivers and streams. Populations in southern Minnesota are experiencing a great amount of stress due to the large amount sediment deposit from the Mississippi River that disturbs flow regimes. The Minnesota DNR has been continuing to monitor and improve water quality of rivers and streams in southern Minnesota. Iowa and New York also have put extra conservation efforts towards the gravel chub. In Iowa the gravel chub was once threatened, but now abundant all over the state. In New York there has been a strong