ABSTRACT
The word Vertisol was coined by Lehman of the University of Ghent and introduced in 1956 at the Sixth International Congress of Soil Science at Paris (Eswaran et al. 1999). In 1960, the Americans adopted it to characterize one of the major categories of their 7th Approximation. The term is now universally used in all classifications. It comes from the Latin vertigo (turning movement). These soils are affected by movements that we shall examine below. They are black, clayey and spectacular in many ways. They represent 2.5 per cent of the soils of the world or 335 million ha, according to FAO. Present in nearly all latitudes, they are most abundant in the dry subtropical zone where dry and humid seasons alternate.
