<P> Much of Africa is made up of plains of the pediplain and etchplain type often occurring as steps . The etchplains are commonly associated with laterite soil and inselbergs . Inselberg - dotted plains are common in Africa including Tanzania, the Anti-Atlas of Morocco, Namibia, and the interior of Angola . One of the most wideaspread plain is the African Surface, a composite etchplain occurring across much of the continent . </P> <P> The area between the east and west coast highlands, which north of 17 ° N is mainly desert, is divided into separate basins by other bands of high ground, one of which runs nearly centrally through North Africa in a line corresponding roughly with the curved axis of the continent as a whole . The best marked of the basins so formed (the Congo basin) occupies a circular area bisected by the equator, once probably the site of an inland sea . </P> <P> Running along the south of desert is the plains region known as the Sahel . </P> <P> The arid region, the Sahara--the largest hot desert in the world, covering 9,000,000 km (3,500,000 sq mi)--extends from the Atlantic to the Red Sea . Though generally of slight elevation, it contains mountain ranges with peaks rising to 2,400 m (7,900 ft) Bordered N.W. by the Atlas range, to the northeast a rocky plateau separates it from the Mediterranean; this plateau gives place at the extreme east to the delta of the Nile . That river (see below) pierces the desert without modifying its character . The Atlas range, the north - westerly part of the continent, between its seaward and landward heights encloses elevated steppes in places 160 km (99 mi) broad . From the inner slopes of the plateau numerous wadis take a direction towards the Sahara . The greater part of that now desert region is, indeed, furrowed by old water - channels . </P>

How many vegetation zones are there across africa