in geological terms, the karoo supergroup refers to an extensive and geologically recent (180–310 million years old) sequence of sedimentary and igneous rocks, which is flanked to the south by the cape fold mountains, and to the north by the more ancient ventersdorp lavas, the transvaal supergroup and waterberg supergroup. it covers two-thirds of south africa and extends in places to 8000 m below the land surface, constituting an immense volume of rocks which was formed, geologically speaking, in a short period of time.