Encyclopaedia Britannica Online
Africa
continent
Table of Contents
Introduction
Geologic history
Land
People
Economy
Africa, the second largest continent (after Asia), covering about one-fifth of the total land surface of Earth. The continent is bounded on the west by the Atlantic Ocean, on the north by the Mediterranean Sea, on the east by the Red Sea and the Indian Ocean, and on the south by the mingling waters of the Atlantic and Indian oceans.
AfricaEncyclopædia Britannica, Inc.
Africa’s total land area is approximately 11,724,000 square miles (30,365,000 square km), and the continent measures about 5,000 miles (8,000 km) from north to south and about 4,600 miles (7,400 km) from east to west. Its northern extremity is Al-Ghīrān Point, near Al-Abyaḍ Point (Cape Blanc), Tunisia; its southern extremity is Cape Agulhas, South Africa; its farthest point east is Xaafuun (Hafun) Point, near Cape Gwardafuy (Guardafui), Somalia; and its western extremity is Almadi Point (Pointe des Almadies), on Cape Verde (Cap Vert), Senegal. In the northeast, Africa was joined to Asia by the Sinai Peninsula until the construction of the Suez Canal. Paradoxically, the coastline of Africa—18,950 miles (30,500 km) in length—is shorter than that of Europe, because there are few inlets and few large bays or gulfs.
Off the coasts of Africa a number of islands are associated with the continent. Of these Madagascar, one of the largest islands in the world, is the most significant. Other, smaller islands include the Seychelles, Socotra, and other islands to the east; the Comoros, Mauritius, Réunion, and other islands to the southeast; Ascension, St. Helena, and Tristan da Cunha to the southwest; Cape Verde, the Bijagós Islands, Bioko, and São Tomé and Príncipe to the west; and the Azores and the Madeira and Canary islands to the northwest.
The continent is cut almost equally in two by the Equator, so that most of Africa lies within the tropical region, bounded on the north by the Tropic of Cancer and on the south by the Tropic of Capricorn. Because of the bulge formed by western Africa, the greater part of Africa’s territory lies north of the Equator. Africa is crossed from north to south by the prime meridian (0° longitude), which passes a short distance to the east of Accra, Ghana.
In antiquity the Greeks are said to have called the continent Libya and the Romans to have called it Africa, perhaps from the Latin aprica (“sunny”) or the Greek aphrike (“without cold”). The name Africa, however, was chiefly applied to the northern coast of the continent, which was, in effect, regarded as a southern extension of Europe. The Romans, who for a time ruled the North African coast, are also said to have called the area south of their settlements Afriga, or the Land of the Afrigs—the name of a Berber community south of Carthage.
The whole of Africa can be considered as a vast plateau rising steeply from narrow coastal strips and consisting of ancient crystalline rocks. The plateau’s surface is higher in the southeast and tilts downward toward the northeast. In general the plateau may be divided into a southeastern portion and a northwestern portion. The northwestern part, which includes the Sahara (desert) and that part of North Africa known as the Maghrib, has two mountainous regions—the Atlas Mountains in northwestern Africa, which are believed to be part of a system that extends into southern Europe, and the Ahaggar (Hoggar) Mountains in the Sahara. The southeastern part of the plateau includes the Ethiopian Plateau, the East African Plateau, and—in eastern South Africa, where the plateau edge falls downward in a scarp—the Drakensberg range. One of the most remarkable features in the geologic structure of Africa is the East African Rift System, which lies between 30° and 40° E. The rift itself begins northeast of the continent’s limits and extends southward from the Ethiopian Red Sea coast to the Zambezi River basin.
Africa contains an enormous wealth of mineral resources, including some of the world’s largest reserves of fossil fuels, metallic ores, and gems and precious metals. This richness is matched by a great diversity of biological resources that includes the intensely lush equatorial rainforests of Central Africa and the world-famous populations of wildlife of the eastern and southern portions of the continent. Although agriculture (primarily subsistence) still dominates the economies of many African countries, the exploitation of these resources became the most significant economic activity in Africa in the 20th century.
Climatic and other factors have exerted considerable influence on the patterns of human settlement in Africa. While some areas appear to have been inhabited more or less continuously since the dawn of humanity, enormous regions—notably the desert areas of northern and southwestern Africa—have been largely unoccupied for prolonged periods of time. Thus, although Africa is the second largest continent, it contains only about 10 percent of the world’s population and can be said to be underpopulated. The greater part of the continent has long been inhabited by black peoples, but in historic times there also have occurred major immigrations from both Asia and Europe. Of all foreign settlements in Africa, that of the Arabs has made the greatest impact. The Islamic religion, which the Arabs carried with them, spread from North Africa into many areas south of the Sahara, so that many western African peoples are now largely Islamized.
This article treats the physical and human geography of Africa, followed by discussion of geographic features of special interest. For discussion of individual countries of the continent, see such articles as Egypt, Madagascar, and Sudan. African regions are treated under the titles Central Africa, eastern Africa, North Africa, Southern Africa, and western Africa; these articles also contain the principal treatment of African historical and cultural development. For discussion of major cities of the continent, see such articles as Alexandria, Cairo, Cape Town, Johannesburg, and Kinshasa. Related topics are discussed in the articles literature, African; literature, South African; architecture, African; art, African; dance, African; music, African; theatre, African; art and architecture, Egyptian; Islam; arts, Islamic; and Islamic world. Davidson S.H.W. Nicol The Editors of Encyclopaedia Britannica Geologic history General considerations
The African continent essentially consists of five ancient Precambrian cratons—Kaapvaal, Zimbabwe, Tanzania, Congo, and West African—that were formed between about 3.6 and 2 billion years ago and that basically have been tectonically stable since that time; those cratons are bounded by younger fold belts formed between 2 billion and 300 million years ago. All of those rocks have been extensively folded and metamorphosed (that is, they have been modified in composition and structure by heat and pressure). Precambrian rock outcrops appear on some 57 percent of the continent’s surface, while the rest of the surface consists of largely undeformed younger sediments and volcanic rocks.
Ruwenzori RangeRugged peaks of the Ruwenzori Range, east-central Africa.P. Jaccod/DeA Picture Library
The oldest rocks are of Archean age (i.e., about 4.6 to 2.5 billion years old) and are found in the so-called granite-gneiss-greenstone terrains of the Kaapvaal, Zimbabwe, and Congo cratons. They consist of gray, banded gneisses, various granitoids, and rather well-preserved volcanic rocks that show evidence of submarine extrusion (i.e., emission of rock material in molten form) and formation under high temperatures. The rock type komatiite is particularly diagnostic of those volcanic sequences and is almost exclusively restricted to the Archean Eon. The cratons were tectonically stabilized by voluminous granite intrusions toward the end of the Archean and were then covered by clastic sediments, some of which contain economically important gold and uranium deposits (e.g., the Witwatersrand System in South Africa).