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 the winter. Grasses are uncommon, making most of the biome unsuitable for grazing. The low rainfall, in fact, discourages most forms of agriculture. An exception is the thriving ostrich-farming industry in the Little Karoo, which is heavily dependent on supplementary feeding with lucerne. The difference between the Succulent Karoo biome and the Nama Karoo biome is that the former receives the little rain that falls as cyclonic rainfall in winter, which has less erosive power than the infrequent but violent summer thunderstorms of the Nama Karoo. Frost is also less common in the Succulent Karoo biome than in the Nama