Vertisols experience significant mixing of soil due to shrinking and swelling of clays. This mixing suppresses horizon formation and makes for a rather featureless soil. The thin, humus-rich Ah has smaller aggregates than the underlying horizon but little colour differentiation. The underlying Bv has experienced significant mixing of soil, and the Bss (ss for slickensides) has large peds with polished surfaces caused by peds being displaced over each other by soil movement. Often the horizon have low levels of calcium carbonate present throughout.
Contributor: Roly St. Arnaud
This Humic Vertisol is very similar to the Vertisol image except that the Ah horizon is at least 10 cm thick. This soil is dry and exhibits the deep cracks characteristic of the shrinking phase of the Vertisol order. Surface soil falls into these cracks and then is mixed into the lower soil when the soil swells during wetter phases. This tends to distribute organic matter throughout the upper soil.
Contributor: Darwin Anderson