Abstract: Studies on clay types in the soils of Arkansas show differences that are important to the soil properties in the soils of the various regions. Part of the agricultural importance of these soils may be related to their mineralogical composition.
The Mississippi River delta area has deposits of soil materials high in montmorillonite-type clay and possessing strong expansion and shrinkage properties. The Arkansas River valley has materials high in illite clay types with montmorillonite. Soils of the Coastal Plain predominate in kaolinite mineral but have sufficient quantities of vermiculite clay to dominate the chemical properties. The Ozark upland soils contain kaolinite and illite in varying proportions.
Much of the state is covered with a silt mantle of varying thickness in which the clay mineral composition is mainly that of montmorillonite and illite.