Afro-Eurasia - Wikipedia
Africa's physical geography, environment and resources, and human East, and their tools have been excavated throughout Asia and Europe. Today, most of the population living in these regions is descended Nomadic pastoralists are people who continually move in order to find fresh grasslands or. Trade Routes between Europe and Asia during Antiquity Some areas had a monopoly on certain materials or goods. They also became cultural and artistic centers, where peoples of different ethnic and cultural backgrounds could meet and transmitted by people moving from one place to another to conduct business. Europe and Asia are sometimes referred to a single continent of Eurasia. Boundaries between continents are somewhat a matter of geographical convention. ones between Asia and Europe, between Africa and Asia, and between North and There is a significant uneven distribution of people between the two portions of.
Cyprus is also placed in Asia by some geographers although the country is often accepted as being included in the modern definition of Europe. The original continental separation was invented by ancient Greek Mariners who named the continents as Europe and Asia.
The two masses of land were separated by a complex waterway flowing from the Aegean Sea to the Sea of Azov. However, the Greeks viewed the continent as physical entities with minimal cultural significance or political content. The threefold system by Herodotus divided the old world into three: Europe, Africa, and Asia. However, the Europe-Asia boundary remained unusual even among the Greek geographers and even Herodotus. The convention was also followed by the Herodotus in the 5th BC. However, a new convention emerged in the following centuries drawing the continental boundaries along the Tanais or the modern Don River.
From the Middle Age through to the 18th century, the traditional division of the Eurasia into two continents followed Ptolemy with boundaries following along the Turkish Strait, the Black Sea, the Azov Sea, and the Don. Role Of Soviet Geographers By the midth century, three main conventions had emerged. The second convention, the boundary line following the Kuma-Manych Depression to the Caspian Sea, is the most popular convention today.
Soviet geographers recommended that the boundary between the two continents be drawn in textbooks from Baydaratskaya Bay, along the eastern foot of the Ural Mountains.
The Soviet definition of the boundary placed the Caucasus entirely in Asia while the Urals are entirely in Europe. Further, most Soviet Geographers preferred the boundary along the Caucasus Crest.
Conclusion Confusion surrounding the definition of the two continents leads to more geographers identifying six continents only, by merging Europe and Asia to form Eurasia. The splitting of Eurasia into Europe and Asia based on the true definition of a continent is now put on record.
Africa | People, Geography, & Facts | santemontreal.info
The separation of Europe from Asia was the effort of European geographers and scholars who sought to separate their region of the world. In fact, some readers find is difficult to accept the land mass forming Europe and Asia as separate continents in any context other than the study of the 20th-century history. In Europe and Asia, the historical boundaries trump the conventional continental criteria. This page was last updated on April 25, Rocks were accreted onto the ancient African continent, the margin of which was then near the present Nile Riverby subduction processes identical to those observed today.
Subduction involves the descent of the edge of one lithospheric plate beneath that of another where two such plates collide.
The interiors of the ancient cratons were not affected by the above tectonic events, and intracratonic sedimentary and volcanic sequences accumulated in large basins.
The most important of those are the Transvaal basin on the Kaapvaal craton that contains economically important iron ore deposits; the Congo basin; and the West African basin, with its thick late Proterozoic sediments including a prominent tillite horizon that marks a major glaciation event at the end of the Precambrian.
The best-preserved assemblages occur in the Kaapvaal and Zimbabwe cratons and contain large deposits of gold and sulfide minerals. The volcanic suites are dominated by basaltic and komatiitic lavas, often interlayered with metasediments and generally referred to as greenstone belts.
Those structures are often found together with layered gneisses, or they are intruded by granitoid plutons. Several generations of greenstones have been recognized. The oldest formed about 3. Some of the oldest traces of life are preserved as unicellular algae in Precambrian cherts of the Barberton greenstone belt in the Transvaal region of South Africa.
One of the most spectacular features marking the end of the Archean is the intrusion of the Great Dyke in Zimbabwea large, layered body of mafic-ultramafic rocks with substantial deposits of chromium, asbestos, and nickel. It is still not clear whether Archean evolution was characterized by the same plate tectonic processes that are seen today, and there are suggestions that the greenstone belts are remnants of ancient oceanic crust.
Cratonic essentially undeformed sediments appear in the stratigraphic record for the first time in the late Archean and are best developed in the Kaapvaal craton of Southern Africa. The early Proterozoic about 2. Of particular interest are extensive stromatolite-bearing limestones and economically important iron formations in the Transvaal sequence of South Africa that provide evidence for an oxygen-rich atmosphere by about 2. About 2 billion years ago the Bushveld Complex —which is one of the largest differentiated igneous bodies on Earthcontaining major deposits of platinumchromiumand vanadium —was emplaced in the northern Kaapvaal craton.
The middle part of the early Proterozoic was dominated by powerful orogenic mountain-building processes that gave rise to fold belts in which sedimentary and volcanic rocks originally deposited in deep basins along the continental margins were severely deformed, metamorphosed, intruded by granitoid plutons, and finally uplifted into mountain ranges, probably as a result of continental collision.
That Eburnian event was particularly active in western Africa, where it deformed the Birimian assemblages; but it was also active in eastern Africa, where it generated the Ubendian belt in southern Tanzaniaand in southwestern Africa, where it formed major rock units in Angola and northern Namibia.
By the end of the early Proterozoic, the Archean crustal blocks had grown into cratons of considerable size. The record of the middle Proterozoic about 1.
Undeformed or only mildly folded successions are found in Southern Africa Waterberg and Matsap sequencesin northern Zambia, and in the Democratic Republic of the Congo. Elsewhere, sedimentary and volcanic sequences were deposited in elongate basins that were later subjected to intense deformation and metamorphism during the Kibaran event. That important thermotectonic episode gave rise to the Kibaran-Burundian fold belt in east-central Africa, the Ruwenzori belt in Ugandaand the Namaqua-Natal belt in South Africa and Namibia.
The late Proterozoic about 1 billion to million years ago is again characterized by platform deposits in stable areas, such as the West African craton Taoudeni and Tindouf basinsthe Congo craton, the Kalahari craton Nama basin of Namibiaand the Tanzania craton Bukoban beds. Tectonic and magmatic activity was concentrated in mobile belts surrounding the stable areas and took place throughout the late Proterozoic, during the so-called Pan-African thermotectonic event.
Long, linear belts—such as the Damara-Katanga of central and southwestern Africa, the Mozambique belt of eastern Africa, and the Dahomey-Ahaggar belt of western Africa—formed during that time, and some of those belts contain diagnostic rock assemblages that indicate that they resulted from continental collisions.
Many late Precambrian sequences of Africa contain one or two beds of tillites sedimentary rocks that are composed of lithified clay and rock sediments produced by the action of icewhich are thought to have resulted from an extensive glaciation that covered much of Africa at that time.
How is the Border Between Europe and Asia Defined?
In the Arabian Eastern Desert of Egypt and in the Red Sea Hills of Sudana predominance of volcanic rocks and granitoids, together with frequent remnants of ancient oceanic crust, document an evolution similar to what is now occurring in the island-arc systems of the southwestern Pacific.
Those rocks clearly demonstrate that plate tectonic processes operated in the late Precambrian.Asia/Continent of Asia/Asia Geography
The continent of Africa may be said to have taken shape during the Paleozoic. A glacial period during the Ordovician is evidenced by widespread deposition tilliteswhich may be seen in southern Morocco, throughout western Africa, and in subequatorial Africa as far south as Namibia.
That tillite sequence marks the transition from the end of the Precambrian to the beginning of the Cambrian Period.
In Egypt and in the Arabian Peninsula their presence has been revealed by drilling. Elsewhere they remain unknown. During the Ordovician Period about to million years agofossiliferous marine sandstone completely covered northern and western Africa, including the Sahara.
The Table Mountain sandstone of South Africa constitutes its only other trace. That period is, in addition, remarkable for broad, large-scale deformation of the African crust, which raised the continental table of the central and western Sahara by approximately 5, feet 1, metres.
Each emergence resulted in the creation of valleys that became flooded when the continent subsided.
Toward the end of the period, the Sahara became glaciated, and tillites and sandstones filled the valleys. A complete change of sedimentation characterized the Silurian Period about to million years agowhich is indicated by the deposits of graptolitic shales those containing small fossil colonies of extinct marine animals of uncertain zoological affinity in the Arabian Peninsula and in northwestern Africa.
Marine fossils of the Devonian Period about to million years ago are found in North Africa and in the Sahara. Fossilized plants that include Archaeosigillaria ancient club mosses may be traced in formations of the earlier Devonian Period in the Sahara and in South Africa Witteberg Series. The Carboniferous Period about to million years ago was marked by the onset of several major tectonic events. Evidence of marine life that existed in the earlier part of the period comes from fossils found in North Africa, the central and western Sahara, and Egypt.
During the middle and later parts of the Carboniferous, the Hercynian mountain-building episodes occurred as a result of collision between the North American and African plates. The Mauritanide mountain chain was compressed and folded at that time along the western margin of the West African craton from Morocco to Senegal. Elsewhere, major uplift or subsidence occurred, continuing until the end of the Triassic Period i. Those structures were synformal folded with the strata dipping inward toward a central axis in the Tindouf and Taoudeni basins of western Algeria, Mauritania, and Mali and antiformal forming a mountainous spine or dome at Reguibat in eastern Western Sahara.
The late Carboniferous Period is represented throughout the Sahara by layers of fossilized plants and sometimes—as in Morocco and Algeria—by seams of coal. Different phenomena may be observed, however, in the region of subequatorial Africa, including the Dwyka tillite, which covers part of South Africa, Namibia, Madagascaran extensive portion of the Congo Basinand Gabon.
At several places in South Africa, the Dwyka strata are covered by thin marine layers that serve to demarcate the transition from the Carboniferous to the Permian Period and that form the beginning of the great Karoo System. Marine fossils of the Permian Period about to million years ago are visible in southern Tunisiain Egypt, in the Arabian Peninsula, on the coasts of Tanzania, and in the Mozambique Channel. Elsewhere, traces of the Permian are of continental rather than marine origin and are included in the Karoo System in South Africa.
There, the lower Permian strata are known as the Ecca Series and are divided into three groups: The upper Permian is represented by the lower part of the Beaufort Serieswhich continued forming into the early Triassic Period.
The Beaufort Series is almost 10, feet 3, metres thick and is famous for its amphibian and reptile fossils; a similar series is also found in southern Russia. The absence of primary marine formations throughout Southern Africa should be emphasized.