Everything about North Asia totally explained
North Asia or
Northern Asia is sometimes defined as a
subregion of
Asia consisting only of the Asian portion of
Russia. The term isn't widely used. Sometimes, North Asia is instead used to designate parts of East Asia and/or Central Asia, with Asian Russia lumped with
Eastern Europe instead.
The
Phillips Illustrated Atlas of the World 1988 defines it as being most of the former
USSR, the part that's to the east of the
Ural Mountains. A definition pre-dating the USSR is an 1882 one by Keane and Temple, who defined it as "the two great administrative divisions of West and East
Siberia, whose capitals are
Omsk and
Irkutsk respectively". It was, according to them "one vast political system, comprising nearly one-third of the whole continent, and, with a few trifling exceptions, directly administered by Russia".
Demographics
In 1875, Chambers reported the population of Northern Asia to be 8 million.
Most estimates nowadays are that there are around 40 million Russians east of the Urals.
Geography
There are no mountain chains in Northern Asia to prevent air currents from the Arctic flowing down over the plains of
Siberia and
Turkestan.
Geomorphology
The geomorphology of Asia in general is imperfectly known, although the deposits and mountain ranges are well known.
To compensate for new
sea floor having been created in the
Siberian basin, the whole of the
Asian Plate has pivoted about a point in the
New Siberian Islands, causing compression in the
Verkhoyansk mountains, which were formed along the eastern margin of the Angara Shield by
tectonic uplift during the
Mesozoic Era. There is a southern boundary to this across the northern margin of the
Alpine folds of Iran, Afghanistan, India, Nepal, and Bhutan, which at the east of
Brahmaputra turns to run south towards the
Bay of Bengal along the line of the
Naga hills and the
Arakan Yoma, continues around
Indonesia, and follows the edge of the
continental shelf along the eastern seaboard of
China. The
Eurasian Plate and the
North American Plate meet across the neck of
Alaska, following the line of the
Aleutian Trench, rather than meeting at the
Bering Straits.
Northern Asia is built around the Angara Shield, which lies between the
Yenisey River and the
Lena River. It developed from fragments of
Laurasia, whose rocks were mainly pre-
Cambrian crystalline rocks,
gneisses, and
schists, and
Gondwana. These rocks can be found in the Angara Shield, the
Inner Mongolian-Korean Shield, the
Ordes Shield and the
South-East Asia Shield. The fragments have been subject to
orogenesis around their margins, giving a complex of plateaux and mountain ranges. One can find
outcrops of these rocks in unfolded sections of the Shields. Their presence has been confirmed below Mesozoic and later sediments.
There are three main periods of mountain building in Northern Asia, although it has occurred many times. The outer fold mountains, that are on the margins of the Shields and that only affected Asia north of the line of the
Himalayas, are attributed to the
Caledonian and
Hercynian orogenies of the late
Palaeozoic Era. The Alpine origeny caused extensive folding and faulting of Mesozoic and early
Tertiary sediments from the
Tethys geosyncline. The Tibetan and Mongolian plateaux, and the structural basins of
Tarim,
Qaidam, and
Junggar, are delimited by major east-west lithospheric faults that were probably the results of stresses caused by the impact of the
Indian Plate against Laurasia. Erosion of the mountains caused by this orogeny has created a large amount of sediment, which has been transported southwards to produce the
alluvial plains of India, China, and Cambodia, and which has also been deposited in large amounts in the Tarim and
Dzungarian basins.
Northern Asia was
glaciated in the
Pleistocene, but this played a less significant part in the geology of the area compared to the part that it played in
North America and
Europe. The Scandanavian ice sheet extended to the east of the Urals, covering the northern two thirds of the
Ob Basin and extending onto the Angara Shield between the
Yenesei River and the
Lena River. There are legacies of mountain glaciation to be found on the east Siberian mountains, on the mountains of the
Kamchatka Peninsula, on the
Altai, on
Tien Shan, and on other small areas of mountains,
ice caps remain on the islands of
Severnaya Zemlya and
Novaya Zemlya, and several
Central Asian mountains still have individual glaciers. Siberia itself has
permafrost, ranging in depths from 30
m to 600m and covering an area of 9.6 million
km².
Several of the mountainous regions are volcanic, with both the
Koryat mountains and the Kamchatka Peninsula having active
volcanoes. The
Anadyr plateau is formed from
igneous rocks. The
Mongolian plateau has an area of
basaltic
lavas and
volcanic cones.
The Angara Shield also underlies the lowlands of the
Ob River, but to the south and east in the Central Asian mountains and in the East Siberian mountains there are folded and faulted mountains of Lower Palaeozoic rocks.
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