Himalayas(redirected from Himalayan Mountains)
Also found in: Dictionary, Thesaurus.
Himalayas(hĭmäl`əyəz, hĭməlā`əz) [Sanskrit,=abode of snow], great Asian mountain system, extending c.1,500 mi (2,410 km) E from the Indus River in Pakistan through India, the Tibet region of China, Nepal, E India, and Bhutan to the southern bend of the Brahmaputra River in SE Tibet. For most of its length, the Himalayas comprise two nearly parallel ranges separated by a wide valley in which the Indus and Sutlej rivers flow westward and the Brahmaputra flows eastward. The northern range is called the Trans-Himalayas. The southern range has three parallel zones: the Great Himalayas, the perpetually snow-covered main range in which the highest peaks (average elevation 20,000 ft/6,100 m) are found; the Lesser Himalayas with 7,000 to 15,000 ft (2,130–4,570 m) elevations; and the southernmost Outer Himalayas, 2,000 to 5,000 ft (610–1,520 m) high. A relatively young and still growing system subject to severe earthquakes, the Himalayas' main axis was formed c.25 to 70 million years ago as the earth's crust folded against the northward-moving Indian subcontinent. Some 30 peaks rise to more than 25,000 ft (7,620 m), including Mt. EverestEverest, Mount,
peak, 29,029 ft (8,848 m) high (as officially recognized by China and Nepal; rock height only, 29,016 ft/8,844 m), on the border of Tibet and Nepal, in the central Himalayas. It is the highest elevation in the world.
..... Click the link for more information. (29,029 ft/8,848 m) and KanchenjungaKanchenjunga,
, or Kinchinjunga
, mountain, on the India-Nepal border, E Himalayas; geologically regarded as part of the main axis of the Himalayan range.
..... Click the link for more information. (28,208 ft/8,598 m), the world's highest and third highest peaks. Himalayan peaks have long been the goal of mountaineers. The towering ranges are penetrated by many roads and tracks, and air flights reach remote towns. Railroads reach only the southern foothills; from there the main route follows footpaths across primitive bridges, ropeways, and high mountain passes. Improved roads run between Kashmir and China and from India through Nepal to China, and there are major airports at Katmandu and Srinagar. The aridity of the Tibetan plateau and the Tarim basin of W China results from the interception of the moisture-laden northwest monsoon by the Himalayas' southern face. Consequently, the northern slopes receive relatively light snowfall and have little drainage, while the snow-covered and extensively glaciated southern slopes give rise to the Indian subcontinent's major rivers, including the Indus, Sutlej, Ganges, and Brahmaputra. Little of the region is inhabitable or of great current economic value. The southern piedmont plains of Tarai and Duars were formerly malarial jungle and swamps but have been converted to agriculture, with many wild animals in nature preserves. Grazing is possible on some of the gentler slopes, and extensive farming is carried on in the valleys; there is some lumbering in the forests found below 12,000 ft (3,660 m). Limited amounts of iron ore, gold, and sapphires are worked in the west. The Himalayan rivers offer much scope for hydroelectric power and irrigation. Hill resorts such as Shimla, Naini Tal, Mussoorie, and Darjeeling are popular summer retreats from the heat of the Indian plains. The Himalayas are associated with many legends in Asian mythology (see abominable snowmanabominable snowman
, humanlike creature so named because it is associated with the perpetual snow region of the Himalayas. A figure unknown except through tracks ascribed to it and through alleged encounters, it is described as being 6 to 8 ft (1.8 to 2.
..... Click the link for more information. ); on isolated slopes are found the retreats of rishis (holy sages), gurus (teachers), and Tibetan monks.
the highest mountain system in the world, located in the territories of India, China, Nepal, and Pakistan, between the Tibetan Plateau on the north and the Indo-Gangetic Plain on the south. The Himalayas are the world’s greatest mountain system, with the tallest peaks, the greatest differences in elevation over short distances, and the deepest gorges (as much as 4-5 km). Length, more than 2,400 km; width, from 180 to 350 km; area, about 650,000 sq km. The average height is about 6,000 m, and there are 11 peaks higher than 8,000 m (Mount Chomolungma [Everest], 8,848 m, is the world’s highest peak).
The Himalayas have precise morphological and physical-geographical borders: on the north, the longitudinal tectonic valleys of the upper courses of the Indus and Tsangpo (Brahmaputra) rivers; on the south, the northern edge of the Indo-Gangetic Plain; on the northwest, the Hindu Raj Range; and on the east, the gorge of the Brahmaputra River. The Himalayas are the major orographic, climatic, and floristic barrier between the deserts of Central Asia and the tropical landscapes of south Asia. However, because antecedent gorges of the Indus, Sutlej, Karnali, and Arun rivers flow through the range, the watershed of the Indian Ocean basin and of an indefinite region of Central Asia passes not through the Himalayas but through the mountain systems bordering it on the north—the Karakoram and the Trans-Himalayas.
Relief. The Himalayas rise sharply over the Indo-Gangetic Plain in three vast steps. The first step is formed by the southern foothills of the Himalayas, the Siwalik Range, strongly dissected by deeply cut gorges of numerous rivers (the width on the west is 120 km; to the east, from 88° E long., it narrows to 5-10 km). The average height is 900-1,200 m. This range is separated from the next step by a large fault, along which there are a series of intermountain basins that were occupied by lakes in the past. The second step is the Lesser Himalayas, a system of separate mountain massifs and ranges (average height 3,000-4,000 m, peaks as high as 6,000 m). The mountains are strongly dissected and are characterized by sheer southern and more gently declining northern slopes. The western part, the Pir Panjal range, is a serrated narrow crest on a broad outlying foundation. In the central part (the Dhaoladhar and the Mahabharat ranges) the mountains rise sharply (to 5,000 m); sharp crests and deep valleys are characteristic. To the east of the tectonic valley of the Tista River, the southern slope is divided by hanging valleys named duars (doors). The second step is divided from the third by a wide depression with a chain of tectonic intermountain depressions and ancient glacial hollows (such as Katmandu and Srinagar). The third step, the Great Himalayas (the major Himalayan range), has a width of 50-90 km. It begins to the northwest of the Nanga Parbat massif (8,126 m), where it is the broadest (more than 300 km); it has raised edges, between which lie high uplands (such as Deosai and Rupshu). To the southeast of the valley of the Sutlej River, the Great Himalayas form a powerful crest, with a series of very high glacier-covered massifs and peaks. To the east of the Tista River, the Great Himalayas become much lower. Here usually deep river valleys and comparatively little dissected massifs and dome-shaped peaks are found.
Geological formations and mineral resources. In its geological structure, the Himalayas are divided (from north to south) by a series of parallel tectonic zones. Along the south of the foot of the hills stretches the sub-Himalayan (Indo-Gangetic) foothill depression, filled by Cenozoic terrigenous deposits of the molasse type, with a total thickness of as much as 10 km. The bedding of the rock is horizontal on the south and inclined on the north, with folds and thrusts overturned toward the south in the Siwalik Range.
The main boundary fault (of the deep type) divides the sub-Himalayan depression from the zone of development of the Precambrian metamorphic rock of the Lesser and Great Himalayas. Among the Precambrian rock of the Lesser Himalayas are tectonically compressed blocks of Paleozoic formations (Krol suite), and presumably Mezozoic formations (Tal suite); here are found continental accumulations of the Gondwana system (Upper Paleozoic) and effusive rocks of the main complex (Panjal traps). Incidents are known of the movement of certain thicknesses on others from the north to the south, but the true amplitude of these movements cannot be determined, since the stratigraphy of ancient thicknesses has been inadequately studied. Many researchers (A. Gannsser and others) consider these to be large movements and overthrust overlappings. The complex of Precambrian rocks of the Great Himalayas (the southern slope and the axis of the Great Himalayan range) are gneiss, crystalline shale, phyllite, and other extremely metamorphized layers; complicated by microplication and plication, they form large dome-shaped rises.
The main boundary fault (sometimes referred to as “the structural joint of the Indus”) is a system of sheer gaps, inclined to the north and accompanied by ophiolite; it separates the next tectonic zone (the Tibetan Himalayas, which occupy the northern slope of the Great Himalayan Range), a part of the Vale of Kashmir, and the upper reaches of the Indus and the Brahmaputra; it is composed of an uninterrupted succession of slightly metamorphized sedimentary rocks from the upper Precambrian to the Cretaceous and Paleogenic inclusively. With regard to structure, this is a system of large synclinoria complicated on the wings by smaller folds, overturning the core of the synclinoria to the side. The best section has been studied in the valley of the Spiti River (a tributary of the Sutlej River).
The geological history of the Himalayas is interpreted by researchers in various ways. The Soviet geologists M. V. Muratov, I. V. Arkhipov, G. P. Gorshkov, and others relate the Himalayas to the alpine geosynclinal (folded) region, which arose inside the Tethys geosyncline; many scholars, including the Soviet scientists B. P. Barkhatov, D. P. Rezvoi, V. M. Sinitsyn, and B. A. Petrushevskii and the Swiss scientist A. Gannsser, see the fact that typical geosynclinal sedimentary formations of Alpine age are not found in the Himalayas as an indication that the Himalayas were formed as the result of reworking and activization in the Neocene Anthropogenic period of the northern part of the Precambrian Indus platform; in this the Himalayas are sharply distinguished in the history of their geological development from the Sulaiman to the southwest and the Arakan Yoma to the southeast, rising out of the alpine geosynclines.
Mineral resources are represented by deposits of copper, gold, chromite, and sapphire, associated with the complex of metamorphic and magmatic rock of the Lesser and Great Himalayas. In the sub-Himalayan foothill flexure there are deposits of oil and gas.
Climate. The Himalayas form a sharp climatic division between the equatorial monsoon region of Hindustan and the continental region of Central Asia. The climate of the western Himalayas is characterized by sharp fluctuations in temperature and by strong winds. The winter is cold (average January temperature, −10° C to −18° C), with violent snowstorms above 2,500 m. The summer is warm (average temperature in July is about 18° C) and dry. The influence of the monsoons is not great and is noticeable only in a certain increase in humidity and cloudiness in July and August. Precipitation (about 1,000 mm per year) is associated with cyclones, during which three to four times less rain falls in the valleys and depressions than on the mountain slopes. The major passes are free of snow at the end of May. In the western Himalayas at an altitude of 1,800 to 2,200 m are located most of the climatic health resorts of India (Shimla, for example). The eastern area has a hotter and more humid climate, with monsoon rainfall; 85-95 percent of the yearly precipitation falls from May to October. In summer, at a height of 1,500 m, temperatures on the slopes reach 35° C; in the valleys, temperatures reach 45° C. Rain falls almost continually. On the southern slopes (at a height of 3,000 to 4,000 m), precipitation ranges from 2,500 mm in the west to 5,500 mm in the east; in the interior regions, it is about 1,000 mm. In winter, at a height of 1,800 m, the average January temperature is 4° C; higher than 3,000 m, the temperatures are below freezing. Snowfall occurs annually above 2,200-2,500 m elevation; in the valleys, there are dense fogs. The northern slopes of the Himalayas have a cold mountain-desert climate. The daily temperature ranges as much as 45° C; rainfall is about 100 mm per year. In summer, at a height of 5,000 to 6,000 m, the temperature is above freezing only during the day. The relative humidity of the air is 30-60 percent. In winter, the snow often evaporates without melting.
Rivers and lakes. The network of rivers is more extensive on the southern slope. The upper courses of rivers are fed by snow and glaciers, with a sharp fluctuation in flow over a 24-hour period; the middle and lower currents are fed by rain, with the maximum flow in summer. The valleys are narrow and deep. There are many rapids and waterfalls. Lakes of tectonic origin are found, as well as glacial lakes, which are especially numerous in the western Himalayas (Wular, Tso Morari, and others).
Glaciers. The total area of glaciers is more than 33,000 sq km. The longest glaciers are located in the massifs of the Chomolungma (up to 19 km) and Kanchenjunga (26 and 16 km); in the Kumaon Himalayas there are the glaciers Milam (20 km) and Gangotri (32 km); in the Punjab Himalayas, Durung-Drung (24 km) and Barmal (15 km). In Kashmir, the lower border of the glaciers is 2,500 m; in the central Himalayas, 4,000 m. Glaciers are more developed in the western Himalayas. On the west, the altitude of the snow line on the southern slope is 5,000 m and on the northern slope, 5,700-5,900 m; on the east, it is 4,500-4,800 and 6,100 m, respectively. The glaciers, primarily of the Dendrite (Himalayan) type, descend to 1,300-1,600 m below the snow line. Glaciers of the Turkestan type are found; they have néé basins, small compared to the regions of flow, which are fed primarily by avalanches and the sliding of hanging glaciers. On the northern slopes, gigantic curtains of fluted ice are characteristic, covering many peaks to their summit.
Landscapes. The landscapes of the Himalayas are especially varied, particularly on the southern slopes. Along the foothills from the east to the valley of the Jamuna River stretches a marshy strip of tree-bush undergrowth (jungles) of soapwood, mimosa, fan palm, bamboo, banana, and mango in black-silt soil. Higher, up to 1,000 to 1,200 m on the windy slopes of mountains and in river valleys, there are evergreen tropical rain forests of palm, laurels, screw-pines, treelike ferns, bamboo, and twining lianas (as many as 400 species). Above 1,200 m in the west and 1,500 m in the east, a strip of evergreen broad-leaved forest grows, consisting of various species of oak and magnolia; above 2,200 m there are temperate forests, with deciduous trees (alder, hazel, birch, and maple) and conifers (Deodar cedar, blue pine, silver spruce), with moss and lichen covering the soil and tree trunks. At a height of 2,700 to 3,600 m, conifer forests are predominant, including silver noble fir, larch, tsugi, and juniper, with a thick undergrowth of rhododendrons. Red earth is characteristic of the lower part of the forested belt; brown forest soil is found higher up. In the subalpine belt there is juniper-rhododendron undergrowth. The highest border of alpine meadows is about 5,000 m, although sparse vegetation (Arenaria, edelweiss) is found above 6,000 m.
The landscapes of the western Himalayas are more xerophytic. Terai-type vegetation is absent; the lower slopes are occupied by rare xerophytic forests and bushes; higher up there are monsoon deciduous trees, with sal predominating. From 1,200 to 1,500 m, Mediterranean subtropical species appear: evergreen stone oak, golden-leaved olive trees, and acacia; in the coniferous forests, Deodar cedar, long-needled pine (chir pine), and Macedonian blue pine. The brush undergrowth is sparser than in the east, and the alpine vegetation is richer. In the forested belt, red soil and brown soil with little humus predominate; higher, there is brown pseudopodzol, and in the alpine belt, mountain meadow. In the forests of the lower slopes and in the Terai, there are large mammals: elephants, rhinoceros, buffalo, wild boars, and antelopes. Predators include tigers and leopards. There are many primates (primarily macaques and langurs [Presbytis]) and birds (peacocks, pheasants, and parrots).
On the northern slopes of the Himalayas, mountain-desert landscapes predominate, with sparse, dry grass and bushes. Trees (groves of low poplars) are found primarily in river valleys. Representatives of Tibetan fauna predominate: Himalayan bears, wild goats, wild sheep, and yaks. There are many rodents. The slopes are cultivated as high as 2,500 m. Plantation culture predominates: tea bushes and citrus. Rice is grown on irrigated terraces. In the northern Himalayas, hull-less barley is found at altitudes up to 4,500 m.
REFERENCESRiabchikov, A. M. Priroda Indii. Moscow, 1950.
Spate, O. H. K. Indiia i Pakistan. Moscow, 1957. (Translated from English.)
Arkhipov, I. V., M. V. Muratov, and E. S. Postel’nikov. “Osnovnye cherty stroeniia i istorii razvitiia alpiiskoi geosinklinal’noi oblasti.” In Mezhdunarodnyi geologicheskii kongress, 22-i. [N. p.] 1964.
Doklady sovetskikh geologov—Problema 11: Gimalaiskii i al’piiskii orogenez. Moscow, 1964.
Rezvoi, D. P. “O velikom georazdele Aziatskogo materika.” Ibid.
Rezvoi, D. P. “Tektonika Gimalaev.” In Skladchatye oblasti Evrazii (Materialy soveshchaniia po problemam tektoniki v Moskve). Moscow, 1964.
Gannsser, A. Geologiia Gimalaev. Moscow, 1967. (Translated from English.)
Dyhrenfurth, G. Tretii polius. Moscow, 1970. (Translated from German.)
L. I. KURAKOVA, A. M. RIABCHIKOV, and D. P. REZVOI (geological structure and mineral resources)