Africa

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Highlands

The highest elevations in Africa are found in the various ranges of East Africa. After Kilimanjaro, the next highest peaks are Mount Kenya (5,199 m/17,057 ft), north of Kilimanjaro in central Kenya; Margherita Peak (5,109 m/ 16,762 ft) in the Ruwenzori Range on the border between Uganda and the Democratic Republic of the Congo (DRC); Ras Dashen (4,620 m/ 15,157 ft) in the Ethiopian Highlands of northern Ethiopia; Mount Meru (4,565 m/ 14,977 ft), close to Kilimanjaro in Tanzania; and Mount Elgon (4,321 m/ 14,177 ft) on the Uganda-Kenya border.

Africa’s other major mountainous regions occur at the northern and southern fringes of the continent. The Atlas Mountains, a system of high ranges, extend for 2,200 km (1,400 mi) across Morocco, Algeria, and Tunisia, roughly parallel to the northern coast. These ranges enclose a number of broad inland basins and plateaus. In the west, the High (or Grand) Atlas contains Toubkal (4,165 m/ 13,665 ft), the highest peak of the system. Toward the east, the Atlas consists of two parallel ranges: the Tell Atlas to the north and the Saharan Atlas to the south.

In southern Africa, the U-shaped Great Escarpment extends 5,000 km (3,000 mi) along the coast from Angola to Mozambique (an escarpment is a ridge that is steep on one side and slopes down gently on the other). The Drakensberg Mountains form the most pronounced relief of the Great Escarpment, rising to 3,482 m (11,424 ft) at Thabana Ntlenyana in Lesotho.

Cameroon Mountain is the highest peak in West Africa at 4,095 m (13,435 ft). To the north, isolated highlands occur in the desert land of the Sahara, including the Ahaggar Mountains in southern Algeria and the Tibesti in northern Chad.

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Great Rift Valley

The Great Rift Valley is one of the most distinctive features of African topography. Formed where Earth’s crust is being pulled apart by the action of convection currents beneath the surface, rift valleys are long, deep valleys bounded by parallel faults, or fractures, in Earth’s crust. The Great Rift Valley system begins in Syria, in the Middle East, and extends southward, down the length of the Red Sea. It enters Africa at the Afar Depression on the coast of Eritrea and Djibouti, and winds some 5,600 km (3,500 mi) to the coast of southern Mozambique. In its middle section, it breaks into two major branches, the Eastern Rift Valley and the Western Rift Valley. The rift valley is flanked by towering escarpments of up to 1,000 m (3,000 ft) in southern Ethiopia, 1,500 m (4,900 ft) along the Eastern Rift in central Kenya, and 1,300 m (4,300 ft) in the northern part of the Western Rift, along the DRC’s border with Uganda, Rwanda, and Burundi. The southern extremities of the rift system are much less spectacular in size and appearance. For more information, see the Faulting and Rift Valleys section of this article.

Several major lakes, typically long and narrow, are located on the floors of the Western and Eastern rift valleys. The Western Rift contains Lake Albert, Lake Edward, and Lake Kivu to the north, Lake Tanganyika in the middle, and Lake Malawi (Lake Nyasa) to the south. The lakes of the Eastern Rift tend to be smaller and include Lake Naivasha, Lake Natron, and the southern part of Lake Turkana.

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Deserts

The Sahara is the world’s largest desert. It stretches from the Atlantic Ocean to the Red Sea, and from the Mediterranean Sea and Atlas Mountains southward for 2,000 km (1,000 mi) until it merges imperceptibly into the semidesert Sahel region. Most of the desert consists of extensive plains covered with loose gravel and boulders, called reg. The rest of the desert is made up of areas of shifting sand dunes, called erg, interspersed with stretches of bare, rocky areas called hamada.

The Namib and Kalahari deserts of southern Africa are much smaller than the Sahara. The Namib Desert stretches along the Atlantic coast for 1,500 km (930 mi) from southern Angola along the entire length of Namibia, and into western South Africa. The nearby Kalahari Desert, in Botswana, Namibia, and South Africa, is a semiarid region in the center of the Kalahari Basin.

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Coastline

Generally, Africa’s coastline is very even, with few good natural harbors. The coastal plain is narrow around much of the continent, particularly in the south and east. Major escarpments run parallel to the coast in several areas. Most of the Red Sea and Indian Ocean coastline is fringed by coral reefs, which are an obstacle to ships. On the Atlantic coast, waters are generally too cold for coral development. Africa’s best natural harbors are found in the many deep coastal inlets between Senegal and Liberia, especially at the mouths of rivers. Lagoon coasts, with a coastal barrier beach backed by lagoons, are common between Liberia and Nigeria.

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Formation of Africa

Scientists use the theory of plate tectonics to explain the formation of Africa and the other continents. According to this theory, the crust of Earth’s surface consists of a collection of 14 rigid plates floating on an underlying mantle. These plates are in constant motion—moving apart, colliding, and thrusting beneath one another. Africa sits at the center of the African Plate, one of the largest of Earth’s plates.

For much of Earth’s history, the land made up one vast supercontinent known as Pangaea. About 220 million years ago, tectonic activity broke Pangaea apart into the supercontinents of Gondwanaland and Laurasia. Gondwanaland subsequently broke apart as well: First Antarctica, Australia, Madagascar, and the Indian subcontinent broke away, followed by South America. Africa, at the core of Gondwanaland, assumed roughly its present-day shape about 15 million years ago when the formation of the Red Sea split off the Arabian Peninsula.

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