Sedimentary Rocks Sedimentary rocks are the most abundant rock type exposed at the surface of the earth and cover about 99 percent of Kentucky. They were formed by the accumulation of rock fragments, shell fragments, plant material, muds, and sands, which were transported to their present locations by water, air, wind, or ice to form clays , sandstones , shales , coals , and conglomerates .
Clays are ultra fine-grained deposits generally composed of complex silicates.
Coal is a very common sedimentary rock formed from plant material, and different coals are formed from variations in temperature and pressure. Limestone was formed in marine depositional environments and as a chemical precipitate from seawater. Dolostone is a limestone that has been chemically altered. Evaporites such as anhydrite, gypsum, and salt were precipitated by the evaporation of water in arid environments. Other sedimentary rocks accumulated because of physical processes where rivers, deltas, and beaches produced sand deposits and conglomerates.