According to ethnicityology, the South African territory includes the whole southern portion of “high” Africa, to the S of the Limpopo valley and the Kalahari depression. It rests on a very ancient base of Precambrian crystalline rocks, veined by rich gold and uranium veins in the Witwatersrand (Transvaal) region; however, this substratum is largely covered by sediments of the Karroo formation, widespread throughout southern Africa but especially characteristic of the Cape region. From Carboniferous (Paleozoic) to Jurassic age (Mesozoic), these strata are economically very important due to the presence of vast coal deposits. Therefore essentially tabular in structure, the South African territory corrugates only in the extreme southern section of the Cape, where it aligns, due to the Hercynian orogeny, a series of chains, with a trend mostly from E to W, separated by long valleys: in the depressions formed by the capide corrugation, the Great Karroo and the Piccolo Karroo extend. The prevailing morphological element, however, is the raised edge of the plateau; although in several places dismembered by erosion (the main modeling agent of the territory, which was no longer affected by marine ingressions after the Paleozoic, except for slight marginal episodes) in isolated massifs, such as the Bontberg (1922 m) and the Kompasberg (2502 m), the continental edge forms an imposing wall to the E, with the Dragons Mountains, or Drakensberg, characterized by powerful basaltic effusions and with various peaks above 3000 m (the maximum altitudes are however found in Lesotho). Towards the west this raised margin, the Great Escarpment or Grande Scarpata, it progressively lowers up to the terraced shelves of the west coast, while towards the south it is faced by the aforementioned chains of the Cape. A narrow coastal alluvial belt borders almost the whole country; the coast is very regular and generally important, except in the southern area, where the Cape ranges directly overlook the sea. Here the marine erosion has carved the sandstone reliefs in a picturesque way, giving rise to a succession of promontories, with cliff-like coasts, and short stretches of low coasts; the famous Cape of Good Hope, however, is an ancient rocky island welded to the continent. The interior planks are rather monotonous, with an average height between 1200 and 1800 m; they are almost perfectly tabular plateaus, carved by the courses of kopjes, which only the presence at the top of a hard rock cap has spared it from a complete leveling. However, some large regions can be distinguished such as the Transvaal plateau, between the Limpopo valley and the Witwatersrand ridge, followed by the Orangeplateau, closed by the Great Escarpment, and, towards the NW, the offshoots of the sandy desert of the Kalahari.
Hydrographically, the country, although divided between different basins, essentially pays tribute to the Atlantic Ocean, especially through the Orange (1860 km), the main river in South Africa, which originates in Lesotho from the Maluti Mountains and whose vast basin (1,020,000 km²) corresponds to a large part of the plateaus; the course of the river, however, is bumpy by rapids and waterfalls that make navigation difficult, also hampered by the very irregular regime. Among its tributaries, the Vaal (1200 km) and the Molopo are of some importance (approx. 1000 km), which marks the border with Botswana for a long stretch, but which is almost always dry. The Olifants also descends to the Atlantic, which flows into the bay of Sant’Elena after having collected the waters of the Grande Karroo. Among the tributaries to the Indian Ocean, the main one is the Limpopo (1600 km), which originates from the Witwatersrand with the name of Krokodil and which drains the northern section of the Transvaal, then widely affecting Mozambique; also for the Limpopo the irregularity of the profile and the regime jeopardizes navigation. The other rivers almost all originate on the Great Escarpment and have a normal course to the coast (among the many the Tugela is famous which originates on the border with Lesotho and forms, with a series of jumps, the homonymous waterfalls, second in the world for height, with 948 m) except those of the Cape area, poorts), which offered easy routes for road and rail communications. Finally, the north-western areas are arid and practically devoid of rivers.