The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.
In southern Africa, rocks of the Karoo Supergroup cover almost two thirds of the present land surface, making part of the 75% of sediments or sedimentary rocks covering the earth including all of Lesotho, almost the whole of Free State, and large parts of the Eastern Cape, Northern Cape, Mpumalanga and KwaZulu-Natal Provinces of South Africa. Karoo supergroup outcrops are also found in Namibia, Eswatini, Zambia, Zimbabwe and Malawi, as well as on other continents that were part of Gondwana. The basins in which it was deposited formed during the formation and breakup of Pangea. The type area of the Karoo Supergroup is the Great Karoo in South Africa, where the most extensive outcrops of the sequence are exposed. Its strata, which consist mostly of shales and sandstones, record an almost continuous sequence of marine glacial to terrestrial deposition from the Late Carboniferous to the Early Jurassic. These accumulated in a retroarc foreland basin called the "main Karoo" Basin. This basin was formed by the subduction and orogenesis along the southern border of what eventually became Southern Africa, in southern Gondwana. Its sediments attain a maximum cumulative thickness of 12 km, with the overlying basaltic lavas (the Drakensberg Group) at least 1.4 km thick.
