Fauna of South Africa the world’s seventeen megadiverse countries. In the extreme northwest of the country is true desert, which is the southernmost end of the Namib desert, a desert that is at least 55 million years old, making it the oldest desert in the world. This arid corner intergrades into the extensive semi-arid Karoo found across much of South Africa, covering the Northern Cape and into parts of the Western Cape, Eastern Cape and the Free State. This biome used to be extensive grassland in the past, but has become dominated by small shrubs and succulents due to centuries of overgrazing. To the
Karoo sediments. This exposed the dolerite sills, which were more resistant to erosion than the Karoo sediments, forming one of the most characteristic features of the Karoo landscape, namely the flat topped hills, called "Karoo Koppies". The geology of the region bears no resemblance to that of the Great Karoo (see the diagram on the left, of a NS geological cross-section through the Little and Great Karoos). The valley is an integral part of the Cape Fold Mountain Belt, with the two ranges on either side composed of extremely hard, erosion-resistant, quartzitic sandstone belonging to the 450- to 510-million-year-old Table Mountain