Botswana and 30°E. The country is predominantly flat, tending toward gently rolling tableland. Botswana is dominated by the Kalahari Desert, which covers up to 70% of its land surface. The Okavango Delta, one of the world's largest inland deltas, is in the northwest. The Makgadikgadi Pan, a large salt pan, lies in the north. The Limpopo River Basin, the major landform of all of southern Africa, lies partly in Botswana, with the basins of its tributaries, the Notwane, Bonwapitse, Mahalapye, Lotsane, Motloutse and the Shashe, located in the eastern part of the country. The Notwane provides water to the capital through
Libyan Desert Algeria. The sand seas contain dunes up to 512 meters in height, and cover approximately one quarter of the total desert region. Other features are the Aswad al Haruj (the "Black Desert"), a large circular region of black volcanic shield in the centre of the country, and the Hamada al Hamra (the "Red Desert") a rocky plateau to the west, on the Tunisian border, coloured by iron oxide deposits. To the southeast, between Kufra and the Libya-Egypt-Sudan border, lies the Jebel Arkenu, with the associated Arkenu structures, thought to be caused by meteorite strikes. North of the Gilf Kebir plateau,