The geological structure and topography of Central Africa are not very diversified. The central part of the region is occupied by a vast collapse of the Precambrian soil. They are filled with sedimentary rocks of various ages. In the lowest part, which is the bottom of the Congo Basin, these are contemporary river and lake sediments, older rocks reveal themselves on gently rising wings. On the outskirts of the Congo Basin they are not very high, undulating highlands built of Precambrian rocks. These rocks hide numerous mineral resources, of which the most important are: gold, diamonds, copper ore, cobalt, tin, uranium, manganese and iron. The extraction of raw materials developed in Central Africa at the end of the 19th century. – initially in Katanga in the south-east of what is now the Republic of the Congo, thanks to the rich deposits of non-ferrous metals, mainly copper. One of the largest mining and industrial districts in Africa has developed on the border of Congo and Zambia. Mining has developed in the west of the region in recent decades. There are, among others,. crude oil (Cameroon, Gabon, Congo), manganese and iron ore (Gabon) and potassium salts (Congo).
The core of this part of the continent is the old one, Precambrian Crystalline Shield, built of folded metamorphic rocks and granites. On it lie layers of younger sedimentary rocks. Numerous magma intrusions and rock metamorphization resulted in the accumulation of many minerals. South Africa is in this respect the richest region of the continent. Stocks of some raw materials (gold, platinum, diamonds, chromium, wanadu, manganese, antimony, uranium) are among the largest in the world. Most of them are located in a strip stretching from central Zambia (Copperbelt) south through Zimbabwe, Transvaal and Oran (RPA), the main accumulation is in South Africa. Half of the mining output of all Africa is mined here.
Water – the gift of life
Africa is one of the few regions in the world, in which rivers are the unifying and organizing element of the natural space. More than 30% of the continent's surface are drainless areas (most of the Sahara and the western part of the Kalahari, some areas within the Great African Rift Valley), located within the extremely dry tropical climate zone. Seasonal watercourses and dry valleys are typical here, the so-called. wadi, filling with water only after occasional rains. The eastern edge of this zone is drained by the hydrographic system of the lower Nile. On 1/3 on the continent's surface there are constant rivers associated with the humid equatorial zone and the subequatorial zones. The largest river in West Africa is the Niger, to whose shores five countries have access: Guinea, Mali, Niger, Benin i Nigeria. Niger has large seasonal fluctuations in flows, especially in the upper and middle reaches. In years, droughts happen, that it carries only a dozen m3 / s of water, therefore, in the middle section, shipping is only possible seasonally; from Ansongo in Mali to Djebbc in Nigeria it ceases completely due to rapids and rapids. The river is navigable all year round only downstream. In Central Africa, the western fringes of the region are drained into the Atlantic via such rivers, like Ogowe, Sanaga i Benue (tributary of the Niger). Small fragments lie in the catchment area of Lake Chad or in the Nile basin, and most of the region belongs to the Congo Basin (4320 km long and 369 100 km2 of the basin area). Like on other African rivers, Waterfalls and rapids occurring in places are a great difficulty in navigation, where the Congo crosses the boundary of rocks of varying resistance.
The river network is poor in South Africa, and most watercourses are periodic or episodic in nature. Significant periodic fluctuations in flows are characteristic. Most rivers have uneven slopes and numerous waterfalls. Short rivers in particular are characterized by a significant decline, flowing down from the Great Edge. Hydropower resources are significant. The largest river is the Zambezi (2660 km long and 1 330 000 km2 of the basin area), on which two large hydrological lines were built: Kariba i Cabora Bassa. Orange (1860 km long and 1 020 000 km2 of the basin area) it carries the waters west to Adantic through increasingly drier areas, and its flow gradually diminishes; downstream, the river often dries up. Water supply is one of the most serious problems of modern Africa. In countries like Ethiopia, Sudan, Central African Republic, Uganda or Mozambique less than 30% the population has the option of using drinking water, and only Libya and Egypt are high (80%) water availability indicator.