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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.
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