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
Black Rock Desert Black Rock Desert The Black Rock Desert is a semi-arid region "(in the Great Basin shrub steppe eco-region)", of lava beds and playa, or alkali flats, situated in the Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area, a silt playa north of Reno, Nevada that encompasses more than of land and contains more than of historic trails. It is in the northern Nevada section of the Great Basin with a lakebed that is a dry remnant of Pleistocene Lake Lahontan. The Great Basin, named for the geography in which water is unable to flow out and remains in