The surface area of South Africa falls into two major physiographic features: the interior plateau, and the land between the plateau and the sea. The Great Escarpment forms the boudary between these two areas. Its hight above sea level varies from about 1500m in the south-west to 3 482m in the Drakensberg.
Inland from the escarpment lies the interior plateau, which is the southern continuation of the great African plateau, which stretches north to the Sahara desert. The plateau comprises wide plains, with an average hight of 1200m above sea level. Surmounting the plateau in places are a number of well-defined upland blocks. The Lesotho plateau is the most prominent of them (more than 3000m above sea level). In general, the escarpment forms the highest parts of the plateau.
The area between the Great Escarpment and the sea varies in width from a mere 60 to 80km in the west to 80 to 240km in the east and south. There are 3 major subdivisions - the western plateau slopes, the Cape folded belt and adjacent regions, and the eastern plateau slopes.