One of the properties by which a B horizon can be recognized is the accumulation of clay by illuviation. This may occur both by eluviation from above and by lateral migration of dispersed clay from more elevated parts of the landscape.
Marked enrichment with clay results in strong blocky or prismatic structure, cutanic character (clay skins), and a clear transition from the overlying horizon. Such soils have duplex (double-story) character and the B horizon is commonly an impediment to both root growth and water movement.
Clay dispersibility brings with it problems of poor structure, surface crusting and erodibility. Climate is usually sub-humid to semi-arid (Soil forms: Estcourt, Klapmuts, Sterkspruit, Sepane, Valsrivier, Swartland).