Karoo Supergroup of the country, and in the Lebombo mountains along the Mozambique border. Once the layer of hard lava was eroded away, the softer Karoo sediments over the rest of the basin eroded even faster. However, the dolerite sills resisted erosion, protecting the softer Beaufort and Ecca shales beneath them. This created numerous and widespread flat topped hills, known as Karoo Koppies ("koppie" being the Afrikaans term for hill), which are iconic of the Karoo, and, by extension, the South African landscape. The dykes, or vertical fissures which brought the lava to the surface stand out today as linear ridges extending
Karoo desert ephemerals, spaced 50 cm or more apart, and becoming very sparse going northwards into Bushmanland and, from there, into the Kalahari Desert. The driest region of the Karoo, however, is its southwestern corner, between the Great Escarpment and the Cederberg-Skurweberg mountain ranges, called the Tankwa Karoo, which receives only 75 mm of rain annually. The eastern and north-eastern Karoo are often covered by large patches of grassland. The typical Karoo vegetation used to support large game, sometimes in vast herds. Today, sheep thrive on the xerophytes, though each sheep requires about 4 ha of grazing to sustain itself. The