The Park both below and above the Great Escarpment is situated on the Beaufort group of rocks, which form part of the Karoo geological system of deposits. The Beaufort sediments were laid down on a vast alluvial plain covering much of what was to become Southern Africa, when it was still part of Gondwana, beginning about 280 million years ago, and ending about 240 million years ago. These 6 km thick sediments were deposited by rivers similar in size and number to the Ganges, Brahmaputra, and Indus rivers which drain the Himalaya mountains on the Indian subcontinent today. In Gondwana, when the Beaufort sediments were being laid down, the Himalaya-sized mountains were to the south of the present South African coastline, on what is geologically known as the Falklands Plateau, now separated from South Africa by continental drift, and lying as severely eroded islands in the south western Atlantic Ocean. A large variety of amphibians and reptiles lived on the lush vegetation of these well-watered plains, the most interesting of which were the mammal-like reptiles, which have made the Karoo paleontologically famous. Their fossils have been found all over the Karoo. Some of these fossils are on display in the Park, though none of them have been found there.