Vertisol

Vertisols are common in semiarid steppes 
that have distinct wet and dry seasons

Photo credit: Soil Science Division at the University of Idaho
Used with permission

Vertisols are dark black soils rich in expandable clay minerals. The clay readily swells upon wetting and shrinks when dried. Though found in every type of climate they are often found in steppe and wet/dry tropical climates where the soil develops deep cracks as it dries. Surface fragments fall into the cracks and are "swallowed" when the soil swells during wetting. It then develops an "inverted profile" with organic material typically found near the surface of the profile is now found at depth. (See also soil order)