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The pattern of Asia’s landforms is quite complex. It contains the widest variations in relief ranging from the highest mountains and the deepest depressions in the world. Mt. Everest (Sagarmatha) is 29,028 feet (8,848 meters) high, the highest in the world, and the Dead Sea lies at about 1,300 feet (400 meters) below sea level.
Nearly three-fourths of the territory of the mainland is uplands, plateaus, and mountains; the remaining in the form of river-and- coastal plains. Most of the islands that lie in Asia’s southern and southeastern sections (in the Pacific and the Indian Oceans) have also mountainous cores. In the broadest sense, the mountain systems of the mainland may be grouped in three large belts. One extends from Asia’s eastern extremity through several mountains of northeastern Siberia westward to southern Siberia (the Sayan, the Altai) and to the Tien Shan and the Pamirs.
The second belt lies in the western part of the continent from the western extremity in Turkey going generally eastward along Turkey’s northern and southern shores, the Pontic and the Taurus Mountain respectively enclosing the Anatolian Plateau and converging in Armenian Knot, and thence passing through the Elburz Mountains of northern Iran and the Zagros along Iran’s southern coast (with Iranian Plateau between these two ranges), moving eastward through the Hindu Kush in northeast direction to meet the Pamir Knot.
Thus, these two belts make the Pamirs as a pivot, as does the third belt which moves eastward of the Pamirs in a form of several radiating ranges: the Tien Shan in a northeasterly direction, the Himalaya in the southeast, and the Kunlun roughly in the easterly direction.
These mountain systems extend some 5,000 miles (8,000 km) and constitute the largest body of highlands in the world. Within the series of the third belt are located some of the world’s highest, and most rugged mountains, elevated plateaus, low-lying basins and deserts in the “core” or the “heartland” of the continent which form a huge continental barrier difficult to penetrate.
The origin and development of these mountains and other surface features are largely puzzling. The generally accepted theory is that of plate tectonics which is invoked to explain the massive crustal rearrangements that periodically took place in the earth’s geological past, eventually leading to the formation of Asia and world’s other continents.
The beginnings are traced to a single super-continent, known as Pangae which subsequently broke apart into two massive landmasses: Laurasia in the northern hemisphere and Gondwanaland in the southern hemisphere. These two contained several “plates”, which later on separated at the “weak zones” and drifted in various directions.
According to the plate tectonics theory of mountain-building there existed a huge geosynclinal depression or sea, known to the geologists as “Tethys”, between the two vast landmasses—the Laurasian and the Gondwanaland. In the latter contained the African, the Arabian and the Indian plates, into which were poured sediments by the rivers of the two flanking plates.
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The colossal infilling of the sediments in the geosyncline disturbed the gravity equilibrium of the crust of the plates and along with the collision of the plates created forces of mountain-building. As the Gondwana plate moved to the north and the Laurasian plate drifted to the south, the two collided in the zone of convergence, and the sediments in the intervening geosyncline were buckled to form mountain belts. It is believed that the Himalaya and the other ranges of Central Asia were formed by such a collision of the plates.
Subsequent splintering and movement of the plates in the Gondwanaland eventually resulted in the present-day peninsulas of Arabia, Deccan (India), as also the continent of Africa, and parts of Brazil, Australia and Antarctic. This theory maintains that the evolution of the continent’s present surface occurred some 50 million years ago as a result of the plates’ collision, although the plate tectonic forces as far back as hundreds of millions of years ago.
The evolution of plains of North India (the Indus-Ganga plains) is traced to the subsequent history of the plates. As the Himalaya was rising under the impact of the advancing plate from the north, erosional processes were removing sediments in the marine gulfs, separating the northern (Laurasian) plate from the southern, Gondwanaland one of the present-day Indus-Ganga plains resulted from the deposited infilling by the sediments in the geosyncline subsequent to the erosional history of the mountains.
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The erosional processes, it may be noted, are still continuing and the deposits from the Himalaya are being accumulated in the North Indian plains. As the plains are being depressed by the sediments, the lightened Himalaya is rising to maintain equilibrium.
East of the Himalaya, the arrangement of the land forms is convoluted. Part of the Himalaya chain turns into southeastern Asia, and follows topographically into the islands of Indonesia. Mountain chains and hill-lands in China follow, in general northeasterly direction, and are lower in elevation, although the mountains east and north of Tibet including the Nanshan, the Tienshan, and further east the Qinling trend east-westward.
The plateaus and highlands east of Tibet are enclosed, surrounded by higher mountains, somewhat comparable to the plateaus of Anatolia and Iran. The topography in the northeastern section of the continent in eastern Siberia has its own sequence, with several mountain ranges maintaining a northeast- southwest orientation.
The vast “heartland” of the continent has a complex mountain “core”, which acts as a gigantic wheel, the spokes of which are formed by some of the greatest rivers of the world that fan outward from the snow-capped mountains (Hindu Kush, Pamirs, Himalaya, Karakoram, Altun Shan). But some five million square miles (12.9 million sq. km) of the continent’s interior have only inland or landlocked drainage, that is, without any outlet to the open seas.
The rivers rise within or in the margins of Asia’s mountain core, flow for several hundred miles across the deserts and steppe lands and disappear into the great saline lakes, or swamps or into the Aral or the Caspian seas (both inland water bodies).
Rivers Syr and Amu drain into the Aral Sea; whereas several short, swift rivers from the Elburz Mountains in North Iran drain into the southern shore of Caspian Sea; and the Ili River coming from the Tien Shan and flowing through the Taklamakan desert in western China, into Lake Balkhash. The Tarim flows into Lake Lop Nor. Most of these interior inland drainage systems contain relatively small, irrigated oases offering some opportunities for settlement.
A striking feature of Asia’s mainland’s relief is the location of its three peninsulas: the plateau of Arabia, the Deccan in South India and that of Indo-China, composed of old and stable blocks of massifs differing in age, composition, and configuration than the mountain systems in the core of the continent. The pattern of surface configuration of the outlying islands and archipelagoes, mostly located off the southeastern and eastern coasts of the continent, is complicated, consisting mostly of, with few exceptions, mountainous territory, narrow coastal plains, active volcanoes and deeply indented, inhospitable coasts.
Asia’s major rivers, particularly that flow eastward and southward of the complex mountain core in the heartland, have had a profound influence on the distribution of population, and human activity. These river lowlands were settled at very early times in history and played a crucial role in the evolution of Asia’s cultural and economic patterns. Prominent among the rivers are: the Indus, the Ganga and the Brahmaputra (together with their tributaries) in the Indian subcontinent; and the three major rivers of China, viz., the Huanghe, the Chang Jiang (Yangtze Kiang), and Xijiang. Within the valleys of these rivers have developed some of world’s most enduring civilizations and modern nations, and it is in them that most of Asia’s people live.
In Southeast Asia, the Irrawaddy, the Salween and the Mekong are the main rivers. In the North, the rivers that flow northward to the Arctic Ocean are the Ob, the Yenseiy, and the Lena. The lesser streams rise in the mountains in southern Siberia, cross the extensive Siberian lowlands, and freeze over in winter. In spring widespread flooding occurs. The river basins are too cold for human occupation and attempts to exploit forest and mineral resources have been made by the Soviet government only during the last century or so with some success.
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For its size, Asia’s coast is small; the ratio of surface area to the coastline (sq. miles of surface area to the linear miles of coast) is 500 to 1 compared with less than 200 to 1 in Europe. Nearly a fifth of the coast fronts the frozen Arctic Ocean and is commercially useless for practically the entire year.
The waters on the Pacific coast are stormy and in part snowbound during winter. Not surprisingly, these seas were not tempting enough for the early and medieval navigators as the Mediterranean or the Norwegian waters were. If we compare Asia and Europe in terms of the climatic and commercial impact of their coasts, we find strikingly different situations.
The Atlantic and the Mediterranean coasts penetrate deep into Europe’s interior, extending maritime influences far into the land encouraging communications, exchange of ideas and products. In sharp contrast, the Asian waters on the Pacific Ocean are ice-blocked, storm-ridden and confining; separating peoples of different nations instead of linking them, even though the Indian Ocean and its connecting water bodies were not as constricting as the Pacific Ocean has been.
The Asian islands are mostly mountainous. Several of these contain active volcanoes, and are frequented by earthquakes. The highlands of Sri Lanka and Malaysia reach 8,279 feet (2,524 meters) and 13,451 feet (4,101 meters) respectively. The famous peak of Japan Fuji-san reaches the altitude of 12,385 feet (3,776 meters).
Many of the volcanoes in Sumatra and Java (both in Indonesia), and Mindanao in the Philippines reach the altitude of 10,000 feet (3,000 meters). Other larger islands lying off the coast of East Asia—Kurile, Sakhalin, Japan, Taiwan and Hainan—are also mountainous, and several contain volcanoes. While the broad pattern of Asia’s landforms is presented here, details of the surface features of the continent are given in the section dealing with the individual countries.