Karoo Karoo The Karoo ( ; from a Khoikhoi word, possibly "garo" "desert") is a semi desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its extent is also not precisely defined. The Karoo is partly defined by its topography, geology and climate, and above all, its low rainfall, arid air, cloudless skies, and extremes of heat and cold. The Karoo also hosted a well-preserved ecosystem hundreds of million years ago which is now represented by many fossils. The Karoo formed an almost impenetrable barrier to the interior from Cape Town, and 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