Karoo are exposed. These are locally known as the Cango Group, but are probably continuous with the Malmesbury Group that forms the base of Table Mountain on the Cape Peninsula, and similar outcrops in the Western Cape. In the Little Karoo, the outcrop is composed of limestone, into which an underground stream has carved the impressively extensive Cango Caves. The Great Karoo and Little Karoo lie almost entirely within two of South Africa’s eight botanical biomes, namely the Succulent Karoo biome and the Nama Karoo biome, both of which, like the Karoo Geological System, are more extensive than the geographical or
Ryn Desert can drop to a low of . Many small towns are scattered throughout the Ryn Desert, and population density is between 1 and 15 people per square mile. The Ryn lies in a semi-arid climate zone, and receives very little rainfall. High winds sweep across the desert, and in 2001 a dust storm in the Baltic Sea was determined as originating in the Ryn Desert. A study of long-range dust transportation to the Baltic Sea region—by analyzing dust pollution in Scandinavia, showed that aerosol concentrations there were influenced more by the Ryn Desert region than the Sahara Desert in Africa.