Africa, the earth’s second largest continent; 30 million km2, over 1 billion. residents (2010). According to ABBREVIATIONFINDER, the continent is surrounded by the Atlantic Ocean, the Indian Ocean and the Mediterranean; bounded by Asia by the Red Sea and the Suez Canal. The continent also includes the nearby islands, The Canary Islands, Cape Verde, Madagascar, Mauritius, Reunion and Seychelles. A table of African countries, capitals, population and area can be found on Countryaah – Countries in Africa.
Africa is plagued by poverty; first the slave trade and since colonial times led to a severe underdevelopment of the continent. In the second half of the 1900-t. Almost all African countries have become independent, but many continue to be plagued by major problems, including political unrest. The vast Sahara desert separates the real Africa “the black Africa” from North Africa, which historically, politically and culturally belongs to the Mediterranean region and the Middle East. The name Africa was originally the name of the Roman province in the then Carthage area.
Africa geology
Africa – geology, The continent’s geological history stretches more than 3000 million. years back. It contains four Precambrian bedrock shields, which are surrounded by later mountain ranges and partly covered by inland basins with younger sedimentary deposits. The best known, the South African Shield, also has well-preserved remnants of early archaic life with the approximately 3400 million years old bacteria in Barberton Mountain Land, South Africa, and approximately 2900 million years old stromatol algae in Zimbabwe. Barberton Mountain Land contains magnesium-rich lavas, comatites, the formation of which is due to the very high heat production in the Earth’s interior in the early Archaeicum. The South African Shield contains the two large Precambrian magnesium- and iron-rich magmatic bodies, the Great Dyke in Zimbabwe (with chromium deposits) and the Bushveld intrusion in South Africa with the thin, platinum-containing zone, Merensky Reef. In southern Africa lies the diamond leaderkimberlite rocks, whose source areas are the Earth’s mantle beneath a thick, ancient continental crust.
The old shields are surrounded by younger mountain ranges that contain both remnants of older formations and newly formed continental crust. The most important are approximately 600 million years old, and in the Nama layer series from this period are fossils of Africa’s first shell-bearing animals.
Large basins play an important role inside the continent. For several geological periods, many km-thick, quartz-rich sediment packets have been deposited in shallow water during slow subsidence. One of the oldest is the Witwatersrand series of gold- and uranium-containing conglomerates (approximately 2400 million years old), which is the basis for South Africa’s largest gold mines. The page followed Katanga series (about 700 million. Years old) with large copper and koboltforekomster (see Copper Belt), which is influenced by the pan-African orogenese. In central and northern Africa, Chad, Congo and several other basins almost completely cover the ancient shields. The deposits, which consist of sandstone, claystone and limestone, include in particular the period Cambrian to Jurassic. There are signs of icing in the deposits from the Upper Precambrian, Ordovician and Carbon to Permian. The Nubian sandstones (Egypt and Sudan) originate from Perm.
Africa’s ancient shields gathered all under the Pan-African orogenese and was part of Gondwanaland, later in the super continent Pangea. Then, in the Late Cretaceous, Africa, South America, India (with Madagascar) and Antarctica were separated. In the Early Tertiary, the African continent collided with the European, and the Atlas Mountains along the north coast of Africa were formed (at the same time as the Alps in Europe).
Along the Rift Valley in East Africa, southern Africa, and Afar, fracture zones and burial sites with associated volcanism (Kilimanjaro, Mount Kenya, and other East African volcanoes that are still active) and sediment deposition have been developed since Carbon. The Karroo system from Karbon-Jura contains both sandstone and plateau basalts, Drakensberg in Lesotho. All of these events are typical precursors to the splitting of a continent along a rift system.
Africa is rich in mineral deposits. In addition to gold, platinum, diamond and copper deposits, nickel, lead, zinc and other metals are centered in the folded edge zones around the old shields. North Africa contains large phosphate deposits of organic origin; South Africa has large coal deposits. Significant oil discoveries have been made in the Sahara; both Algeria and Libya are among the world’s major oil producers. Africa has a total of 6-7% of the world’s known oil reserves (2004).
Africa – plant geography
Africa – plant geography, Africa’s flora is very diverse between regions, which is mainly due to differences in climate. In Egypt and in parts of Libya, the desert reaches all the way to the Mediterranean, but otherwise the plant growth in the coastal areas of North Africa is closely linked to the Mediterranean. In the past, the areas were predominantly forested with species of pine and evergreen oak, but today they are dominated by evergreen shrubs, maki and garrigue.
After the last ice age, when the border between the Mediterranean and the desert areas was further south than today, certain species from the Mediterranean flora have been isolated on mountains in central Sahara. On the coast of NW Africa, the desert reaches all the way to the Atlantic Ocean and here forms a barrier between the vegetation in the north and that in the south. The vegetation of the desert is sparse and species-poor; only in wadis and oases does lush plant growth occur with acacias and tamarisk.
The flora in the Macaronesian area, ie. Cape Verde, the Canary Islands, Madeira and the Azores are reminiscent of the Mediterranean flora, but also have tropical elements, such as dragon blood and succulent species of wart milk.
Africa’s rainforest area is concentrated along the Guinea coast and in the Congo Basin, where there is a lush, tropical lowland rainforest with many palm trees and tall trees in the pea flower and wart milk families. Ferns and orchids are dominant among the epiphytes; it is a common form of growth in the rainforest that allows the herbs to reach the light. As with wildlife, Africa’s rainforests have far fewer plant species than the rainforests of Asia and South America. In arid areas, the rainforest grows along the rivers as narrow belts of gallery forest, and the highlands are dominated by mountain rainforest with conifers, such as Podocarpus. Above the mountain rainforest in the mountains of East Africa is a subalpine zone with shrub or tree-like heather growths and Philippa. Even higher up is an alpine zone with “rosette trees” of the genera fire goblet and lobelia as well as northern species of star and fescue. The coffee bush originally comes from the Ethiopian Highlands.
North, east and south of the rainforest are large areas of dry forest and savannah. The low trees are leafless during part of the dry season; important genera are Acacia, Combretum and Brachystegia. On the savannah, perennial grasses dominate between the scattered groups of trees. Regular burns, by sweating or as a result of self-ignition, inhibit tree growth, but are beneficial for the spread of grasslands.
The Namib Desert is home to the highly unusual and interesting Welwitschia, a relative of the conifers, and the desert-like Karroo region of inland South Africa has a rich flora of succulent herbs.
The southwestern part of Africa, Cape Province, has a rich and distinctive flora of a type similar to the Mediterranean, with more than 500 species in the bell heather genus. Plant families such as Proteaceae and Restionaceae are prominent here, and the flora seems to be related to the South Australian.
Madagascar has a rich flora of predominantly tropical African character, but with a Malaysian touch. The flamboyant tree, now cultivated throughout the tropics, originates here.
