Africa | geology and geography

Geology and geography

Satellite photo of Africa. The Sahara Desert in the north can be clearly seen.
A composite satellite image of Africa (centre) with North America (left) and Eurasia (right), to scale

Africa is the largest of the three great southward projections from the largest landmass of the Earth. Separated from Europe by the Mediterranean Sea, it is joined to Asia at its northeast extremity by the Isthmus of Suez (transected by the Suez Canal), 163 km (101 mi) wide.[77] (Geopolitically, Egypt's Sinai Peninsula east of the Suez Canal is often considered part of Africa, as well.)[78]

The coastline is 26,000 km (16,000 mi) long, and the absence of deep indentations of the shore is illustrated by the fact that Europe, which covers only 10,400,000 km2 (4,000,000 sq mi) – about a third of the surface of Africa – has a coastline of 32,000 km (20,000 mi).[79] From the most northerly point, Ras ben Sakka in Tunisia (37°21' N), to the most southerly point, Cape Agulhas in South Africa (34°51'15" S), is a distance of approximately 8,000 km (5,000 mi).[80] Cape Verde, 17°33'22" W, the westernmost point, is a distance of approximately 7,400 km (4,600 mi) to Ras Hafun, 51°27'52" E, the most easterly projection that neighbours Cape Guardafui, the tip of the Horn of Africa.[79]

Africa's largest country is Algeria, and its smallest country is Seychelles, an archipelago off the east coast.[81] The smallest nation on the continental mainland is The Gambia.

African plate

Africa
The African Plate
TypeMajor
Approximate area61,300,000 km2 (23,700,000 sq mi)[82]
FeaturesAfrica, Atlantic Ocean, Mediterranean Sea

The African Plate is a major tectonic plate straddling the equator as well as the prime meridian. It includes much of the 10 million years ago, the Somali Plate began rifting from the African Plate along the East African Rift.[83] Since the continent of Africa consists of crust from both the African and the Somali plates, some literature refers to the African Plate as the Nubian Plate to distinguish it from the continent as a whole.[84]

Geologically, Africa includes the Arabian Peninsula; the Zagros Mountains of Iran and the Anatolian Plateau of Turkey mark where the African Plate collided with Eurasia. The Afrotropic ecozone and the Saharo-Arabian desert to its north unite the region biogeographically, and the Afro-Asiatic language family unites the north linguistically.

Climate

Africa map of Köppen climate classification[85]

The climate of Africa ranges from tropical to subarctic on its highest peaks. Its northern half is primarily desert, or arid, while its central and southern areas contain both savanna plains and dense jungle (rainforest) regions. In between, there is a convergence, where vegetation patterns such as sahel and steppe dominate. Africa is the hottest continent on Earth and 60% of the entire land surface consists of drylands and deserts.[86] The record for the highest-ever recorded temperature, in Libya in 1922 (58 °C (136 °F)), was discredited in 2013.[87][88]

Fauna

Africa boasts perhaps the world's largest combination of density and "range of freedom" of wild animal populations and diversity, with wild populations of large carnivores (such as lions, hyenas, and cheetahs) and herbivores (such as buffalo, elephants, camels, and giraffes) ranging freely on primarily open non-private plains. It is also home to a variety of "jungle" animals including snakes and primates and aquatic life such as crocodiles and amphibians. In addition, Africa has the largest number of megafauna species, as it was least affected by the extinction of the Pleistocene megafauna.

Ecology and biodiversity

Tropical beach in Trou-aux-Biches, Mauritius

Africa has over 3,000 protected areas, with 198 marine protected areas, 50 biosphere reserves, and 80 wetlands reserves. Significant habitat destruction, increases in human population and poaching are reducing Africa's biological diversity and arable land. Human encroachment, civil unrest and the introduction of non-native species threaten biodiversity in Africa. This has been exacerbated by administrative problems, inadequate personnel and funding problems.[86]

Deforestation is affecting Africa at twice the world rate, according to the United Nations Environment Programme (UNEP).[89] According to the University of Pennsylvania African Studies Center, 31% of Africa's pasture lands and 19% of its forests and woodlands are classified as degraded, and Africa is losing over four million hectares of forest per year, which is twice the average deforestation rate for the rest of the world.[86] Some sources claim that approximately 90% of the original, virgin forests in West Africa have been destroyed.[90] Over 90% of Madagascar's original forests have been destroyed since the arrival of humans 2000 years ago.[91] About 65% of Africa's agricultural land suffers from soil degradation.[92]