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
Tirari Desert and the Sturt Stony Desert runs aligned with the Birdsville track to the north east. The desert experiences harsh conditions with high temperatures and very low rainfall (mean annual rainfall is below ). The main vehicular access to the desert is via the unpaved Birdsville Track which runs northwards from Marree to Birdsville. The Mungerannie Hotel is the only location between the two towns that provides services. The Tirari Desert region has a number of large cattle stations which are stopping points on the Channel Country aviation mail run. Dulkaninna Station has been run by the same family for 110