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2492) Himalayan Mountains

Gist

The Himalayas are a massive mountain range in Asia, forming a crescent-shaped arc that separates the Indian subcontinent from the Tibetan Plateau and stretches across five countries: India, Nepal, Bhutan, China (Tibet), and Pakistan. Known as the "abode of snow," they contain Earth's highest peaks, including Mount Everest, and influence the climate and rivers of South Asia. 

The Himalayas consists of four parallel mountain ranges from south to north: the Sivalik Hills on the south; the Lower Himalayan Range; the Great Himalayas, which is the highest and central range; and the Tibetan Himalayas on the north. The Karakoram are generally considered separate from the Himalayas.

Summary

The Himalayas, or Himalaya, is a mountain range in Asia separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the Earth's highest peaks, including the highest, Mount Everest. More than 100 peaks exceeding elevations of 7,200 m (23,600 ft) above sea level lie in the Himalayas.

The Himalayas abut on or cross territories of five countries: Nepal, India, China, Bhutan and Pakistan. The sovereignty of the range in the Kashmir region is disputed among India, Pakistan, and China. The Himalayan range is bordered on the northwest by the Karakoram and Hindu Kush ranges, on the north by the Tibetan Plateau, and on the south by the Indo-Gangetic Plain. Some of the world's major rivers, the Indus, the Ganges, and the Tsangpo–Brahmaputra, rise in the vicinity of the Himalayas, and their combined drainage basin is home to some 600 million people; 53 million people live in the Himalayas. The Himalayas have profoundly shaped the cultures of South Asia and Tibet. Many Himalayan peaks are sacred in Hinduism and Buddhism. The summits of several—Kangchenjunga (from the Indian side), Gangkhar Puensum, Machapuchare, Nanda Devi, and Kailash in the Tibetan Transhimalaya—are off-limits to climbers.

The Himalayas were uplifted after the collision of the Indian tectonic plate with the Eurasian plate, specifically, by the folding, or nappe-formation of the uppermost Indian crust, even as a lower layer continued to push on into Tibet and add thickness to its plateau; the still lower crust, along with the mantle, however, subducted under Eurasia. The Himalayan mountain range runs west-northwest to east-southeast in an arc 2,400 km (1,500 mi) long. Its western anchor, Nanga Parbat, lies just south of the northernmost bend of the Indus river. Its eastern anchor, Namcha Barwa, lies immediately west of the great bend of the Yarlung Tsangpo River. The Indus-Yarlung suture zone, along which the headwaters of these two rivers flow, separates the Himalayas from the Tibetan plateau; the rivers also separate the Himalayas from the Karakorams, the Hindu Kush, and the Transhimalaya. The range varies in width from 350 km (220 mi) in the west to 151 km (94 mi) in the east.

Details

Himalayas are great mountain system of Asia forming a barrier between the Plateau of Tibet to the north and the alluvial plains of the Indian subcontinent to the south. The Himalayas include the highest mountains in the world, with more than 110 peaks rising to elevations of 24,000 feet (7,300 meters) or more above sea level. One of those peaks is Mount Everest (Tibetan: Chomolungma; Chinese: Qomolangma Feng; Nepali: Sagarmatha), the world’s highest, with an elevation of 29,032 feet (8,849 meters).

For thousands of years the Himalayas have held a profound significance for the peoples of South Asia, as their literature, mythologies, and religions reflect. Since ancient times the vast glaciated heights have attracted the attention of the pilgrim mountaineers of India, who coined the Sanskrit name Himalaya—from hima (“snow”) and alaya (“abode”)—for that great mountain system. In contemporary times the Himalayas have offered the greatest attraction and the greatest challenge to mountaineers throughout the world.

The ranges, which form the northern border of the Indian subcontinent and an almost impassable barrier between it and the lands to the north, are part of a vast mountain belt that stretches halfway around the world from North Africa to the Pacific Ocean coast of Southeast Asia. The Himalayas themselves stretch uninterruptedly for about 1,550 miles (2,500 km) from west to east between Nanga Parbat (26,660 feet [8,126 meters]), in the Pakistani-administered portion of the Kashmir region, and Namjagbarwa (Namcha Barwa) Peak (25,445 feet [7,756 meters]), in the Tibet Autonomous Region of China. Between those western and eastern extremities lie the two Himalayan countries of Nepal and Bhutan. The Himalayas are bordered to the northwest by the mountain ranges of the Hindu Kush and the Karakoram and to the north by the high and vast Plateau of Tibet. The width of the Himalayas from south to north varies between 125 and 250 miles (200 and 400 km). Their total area amounts to about 230,000 square miles (595,000 square km).

Though India, Nepal, and Bhutan have sovereignty over most of the Himalayas, Pakistan and China also occupy parts of them. In the disputed Kashmir region, Pakistan has administrative control of some 32,400 square miles (83,900 square km) of the range lying north and west of the “line of control” established between India and Pakistan in 1972. China administers some 14,000 square miles (36,000 square km) in the Ladakh region and has claimed territory at the eastern end of the Himalayas within the Indian state of Arunachal Pradesh. Those disputes accentuate the boundary problems faced by India and its neighbors in the Himalayan region.

Physical features

The most characteristic features of the Himalayas are their soaring heights, steep-sided jagged peaks, valley and alpine glaciers often of stupendous size, topography deeply cut by erosion, seemingly unfathomable river gorges, complex geologic structure, and series of elevational belts (or zones) that display different ecological associations of flora, fauna, and climate. Viewed from the south, the Himalayas appear as a gigantic crescent with the main axis rising above the snow line, where snowfields, alpine glaciers, and avalanches all feed lower-valley glaciers that in turn constitute the sources of most of the Himalayan rivers. The greater part of the Himalayas, however, lies below the snow line. The mountain-building process that created the range is still active. As the bedrock is lifted, considerable stream erosion and gigantic landslides occur.

The Himalayan ranges can be grouped into four parallel longitudinal mountain belts of varying width, each having distinct physiographic features and its own geologic history. They are designated, from south to north, as the Outer, or Sub-, Himalayas (also called the Siwalik Range); the Lesser, or Lower, Himalayas; the Great Himalaya Range (Great Himalayas); and the Tethys, or Tibetan, Himalayas. Farther north lie the Trans-Himalayas in Tibet proper. From west to east the Himalayas are divided broadly into three mountainous regions: western, central, and eastern.

Geologic history

Over the past 65 million years, powerful global plate-tectonic forces have moved Earth’s crust to form the band of Eurasian mountain ranges—including the Himalayas—that stretch from the Alps to the mountains of Southeast Asia.

During the Jurassic Period (about 201 to 145 million years ago), a deep crustal downwarp—the Tethys Ocean—bordered the entire southern fringe of Eurasia, then excluding the Arabian Peninsula and the Indian subcontinent. About 180 million years ago, the old supercontinent of Gondwana (or Gondwanaland) began to break up. One of Gondwana’s fragments, the lithospheric plate that included the Indian subcontinent, pursued a northward collision course toward the Eurasian Plate during the ensuing 130 to 140 million years. The Indian-Australian Plate gradually confined the Tethys trench within a giant pincer between itself and the Eurasian Plate. As the Tethys trench narrowed, increasing compressive forces bent the layers of rock beneath it and created interlacing faults in its marine sediments. Masses of granites and basalts intruded from the depth of the mantle into that weakened sedimentary crust. Between about 40 and 50 million years ago, the Indian subcontinent finally collided with Eurasia. The plate containing India was sheared downward, or subducted, beneath the Tethys trench at an ever-increasing pitch.

During the next 30 million years, shallow parts of the Tethys Ocean gradually drained as its sea bottom was pushed up by the plunging Indian-Australian Plate; that action formed the Plateau of Tibet. On the plateau’s southern edge, marginal mountains—the Trans-Himalayan ranges of today—became the region’s first major watershed and rose high enough to become a climatic barrier. As heavier rains fell on the steepening southern slopes, the major southern rivers eroded northward toward the headwaters with increasing force along old transverse faults and captured the streams flowing onto the plateau, thus laying the foundation for the drainage patterns for a large portion of Asia. To the south the northern reaches of the Arabian Sea and the Bay of Bengal rapidly filled with debris carried down by the ancestral Indus, Ganges (Ganga), and Brahmaputra rivers. The extensive erosion and deposition continue even now as those rivers carry immense quantities of material every day.

Finally, some 20 million years ago, during the early Miocene Epoch, the tempo of the crunching union between the two plates increased sharply, and Himalayan mountain building began in earnest. As the Indian subcontinental plate continued to plunge beneath the former Tethys trench, the topmost layers of old Gondwana metamorphic rocks peeled back over themselves for a long horizontal distance to the south, forming nappes. Wave after wave of nappes thrust southward over the Indian landmass for as far as 60 miles (about 100 km). Each new nappe consisted of Gondwana rocks older than the last. In time those nappes became folded, contracting the former trench by some 250 to 500 horizontal miles (400 to 800 km). All the while, downcutting rivers matched the rate of uplift, carrying vast amounts of eroded material from the rising Himalayas to the plains where it was dumped by the Indus, Ganges, and Brahmaputra rivers. The weight of that sediment created depressions, which in turn could hold more sediment. In some places the alluvium beneath the Indo-Gangetic Plain now exceeds 25,000 feet (7,600 meters) in depth.

Probably only within the past 600,000 years, during the Pleistocene Epoch (roughly 2,600,000 to 11,700 years ago), did the Himalayas become the highest mountains on Earth. If strong horizontal thrusting characterized the Miocene and the succeeding Pliocene Epoch (about 23 to 2.6 million years ago), intense uplift epitomized the Pleistocene. Along the core zone of the northernmost nappes—and just beyond—crystalline rocks containing new gneiss and granite intrusions emerged to produce the staggering crests seen today. On a few peaks, such as Mount Everest, the crystalline rocks carried old fossil-bearing Tethys sediments from the north piggyback to the summits.

Once the Great Himalayas had risen high enough, they became a climatic barrier: the marginal mountains to the north were deprived of rain and became as parched as the Plateau of Tibet. In contrast, on the wet southern flanks the rivers surged with such erosive energy that they forced the crest line to migrate slowly northward.

Simultaneously, the great transverse rivers breaching the Himalayas continued their downcutting in pace with the uplift. Changes in the landscape, however, compelled all but those major rivers to reroute their lower courses because, as the northern crests rose, so also did the southern edge of the extensive nappes. The formations of the Siwalik Series were overthrust and folded, and in between the Lesser Himalayas downwarped to shape the midlands. Now barred from flowing due south, most minor rivers ran east or west through structural weaknesses in the midlands until they could break through the new southern barrier or join a major torrent.

In some valleys, such as the Vale of Kashmir and the Kathmandu Valley of Nepal, lakes formed temporarily and then filled with Pleistocene deposits. After drying up some 200,000 years ago, the Kathmandu Valley rose at least 650 feet (200 meters), an indication of localized uplift within the Lesser Himalayas.

Physiography of the Himalayas

The Outer Himalayas comprise flat-floored structural valleys and the Siwalik Range, which borders the Himalayan mountain system to the south. Except for small gaps in the east, the Siwaliks run for the entire length of the Himalayas, with a maximum width of 62 miles (100 km) in the northern Indian state of Himachal Pradesh. In general, the 900-foot (275-meter) elevation contour line marks their southern boundary; they rise an additional 2,500 feet (760 meters) to the north. The main Siwalik Range has steeper southern slopes facing the Indian plains and descends gently northward to flat-floored basins, called duns. The best-known of those is the Dehra Dun, in southern Uttarakhand state, just north of the border with northwestern Uttar Pradesh state.

To the north the Siwalik Range abuts a massive mountainous tract, the Lesser Himalayas. In that range, 50 miles (80 km) in width, mountains rising to 15,000 feet (4,500 meters) and valleys with elevations of 3,000 feet (900 meters) run in varying directions. Neighboring summits share similar elevations, creating the appearance of a highly dissected plateau. The three principal ranges of the Lesser Himalayas—the Nag Tibba, the Dhaola Dhar, and the Pir Panjal—have branched off from the Great Himalaya Range lying farther north. The Nag Tibba, the most easterly of the three ranges, reaches an elevation of some 26,800 feet (8,200 meters) near its eastern end, in Nepal, and forms the watershed between the Ganges and Yamuna rivers in Uttarakhand.

To the west is the picturesque Vale of Kashmir, in Jammu and Kashmir union territory (the Indian-administered portion of Kashmir). A structural basin (i.e., an elliptical basin in which the rock strata are inclined toward a central point), the vale forms an important section of the Lesser Himalayas. It extends from southeast to northwest for 100 miles (160 km), with a width of 50 miles (80 km), and has an average elevation of 5,100 feet (1,600 meters). The basin is traversed by the meandering Jhelum River, which runs through Wular Lake, a large freshwater lake in Jammu and Kashmir northwest of Srinagar.

The backbone of the entire mountain system is the Great Himalaya Range, rising into the zone of perpetual snow. The range reaches its maximum height in Nepal; among its peaks are 10 of the 13 highest in the world, each of which exceeds 26,250 feet (8,000 meters) in elevation. From west to east those peaks are Nanga Parbat, Dhaulagiri 1, Annapurna 1, Manaslu 1, Xixabangma (Gosainthan), Cho Oyu, Mount Everest, Lhotse, Makalu 1, and Kanchenjunga 1.

The range trends northwest-southeast from Jammu and Kashmir to Sikkim, an old Himalayan kingdom that is now a state of India. East of Sikkim it runs east-west for another 260 miles (420 km) through Bhutan and the eastern part of Arunachal Pradesh as far as the peak of Kangto (23,260 feet [7090 meters]) and finally bends northeast, terminating at Namcha Barwa.

There is no sharp boundary between the Great Himalayas and the ranges, plateaus, and basins lying to the north of the Great Himalayas. Those are generally grouped together under the names of the Tethys, or Tibetan, Himalayas and the Trans-Himalayas, which extend far northward into Tibet. In Kashmir and in the Indian state of Himachal Pradesh, the Tethys are at their widest, forming the Spiti Basin and the Zanskar Range.

Drainage of the Himalayas

The Himalayas are drained by 19 major rivers, of which the Indus and the Brahmaputra are the largest, each having catchment basins in the mountains of about 100,000 square miles (260,000 square km) in extent. Five of the 19 rivers, with a total catchment area of about 51,000 square miles (132,000 square km), belong to the Indus system—the Jhelum, the Chenab, the Ravi, the Beas, and the Sutlej—and collectively define the vast region divided between Punjab state in India and Punjab province in Pakistan. Of the remaining rivers, nine belong to the Ganges system—the Ganges, Yamuna, Ramganga, Kali (Kali Gandak), Karnali, Rapti, Gandak, Baghmati, and Kosi rivers—draining roughly 84,000 square miles (218,000 square km) in the mountains, and three belong to the Brahmaputra system—the Tista, the Raidak, and the Manas—draining another 71,000 square miles (184,000 square km) in the Himalayas.

The major Himalayan rivers rise north of the mountain ranges and flow through deep gorges that generally reflect some geologic structural control, such as a fault line. The rivers of the Indus system as a rule follow northwesterly courses, whereas those of the Ganges-Brahmaputra systems generally take easterly courses while flowing through the mountain region.

To the north of India, the Karakoram Range, with the Hindu Kush range on the west and the Ladakh Range on the east, forms the great water divide, shutting off the Indus system from the rivers of Central Asia. The counterpart of that divide on the east is formed by the Kailas Range and its eastward continuation, the Nyainqêntanglha (Nyenchen Tangla) Mountains, which prevent the Brahmaputra from draining the area to the north. South of that divide, the Brahmaputra flows to the east for about 900 miles (1,450 km) before cutting across the Great Himalaya Range in a deep transverse gorge, although many of its Tibetan tributaries flow in an opposite direction, as the Brahmaputra may once have done.

The Great Himalayas, which normally would form the main water divide throughout their entire length, function as such only in limited areas. That situation exists because the major Himalayan rivers, such as the Indus, the Brahmaputra, the Sutlej, and at least two headwaters of the Ganges—the Alaknanda and the Bhagirathi—are probably older than the mountains they traverse. It is believed that the Himalayas were uplifted so slowly that the old rivers had no difficulty in continuing to flow through their channels and, with the rise of the Himalayas, acquired an even greater momentum, which enabled them to cut their valleys more rapidly. The elevation of the Himalayas and the deepening of the valleys thus proceeded simultaneously. As a result, the mountain ranges emerged with a completely developed river system cut into deep transverse gorges that range in depth from 5,000 to 16,000 feet (1,500 to 5,000 meters) and in width from 6 to 30 miles (10 to 50 km). The earlier origin of the drainage system explains the peculiarity that the major rivers drain not only the southern slopes of the Great Himalayas but, to a large extent, its northern slopes as well, the water divide being north of the crest line.

The role of the Great Himalaya Range as a watershed, nevertheless, can be seen between the Sutlej and Indus valleys for 360 miles (580 km); the drainage of the northern slopes is carried by the north-flowing Zanskar and Dras rivers, which drain into the Indus. Glaciers also play an important role in draining the higher elevations and in feeding the Himalayan rivers. Several glaciers occur in Uttarakhand, of which the largest, the Gangotri, is 20 miles (32 km) long and is one of the sources of the Ganges. The Khumbu Glacier drains the Everest region in Nepal and is one of the most popular routes for the ascent of the mountain. The rate of movement of the Himalayan glaciers varies considerably; in the neighboring Karakoram Range, for example, the Baltoro Glacier moves about 6 feet (2 meters) per day, while others, such as the Khumbu, move only about 1 foot (30 cm) daily. Most of the Himalayan glaciers are in retreat, at least in part because of climate change.

Soils

The north-facing slopes generally have a fairly thick soil cover, supporting dense forests at lower elevations and grasses higher up. The forest soils are dark brown in color and silt loam in texture; they are ideally suited for growing fruit trees. The mountain meadow soils are well developed but vary in thickness and in their chemical properties. Some of the wet deep upland soils of that type in the eastern Himalayas—for example, in the Darjeeling (Darjiling) Hills and in the Assam valley—have a high humus content that is good for growing tea. Podzolic soils (infertile acidic forest soils) occur in a belt some 400 miles (640 km) long in the valleys of the Indus and its tributary the Shyok River, to the north of the Great Himalaya Range, and in patches in Himachal Pradesh. Farther east, saline soils occur in the dry high plains of the Ladakh region. Of the soils that are not restricted to any particular area, alluvial soils (deposited by running water) are the most productive, though they occur in limited areas, such as the Vale of Kashmir, the Dehra Dun, and the high terraces flanking the Himalayan valleys. Lithosols, consisting of imperfectly weathered rock fragments that are deficient in humus content, cover many large areas at high elevations and are the least-productive soils.

Climate of the Himalayas

The Himalayas, as a great climatic divide affecting large systems of air and water circulation, help determine meteorological conditions in the Indian subcontinent to the south and in the Central Asian highlands to the north. By virtue of its location and stupendous height, the Great Himalaya Range obstructs the passage of cold continental air from the north into India in winter and also forces the southwesterly monsoon (rain-bearing) winds to give up most of their moisture before crossing the range northward. The result is heavy precipitation (both rain and snow) on the Indian side but arid conditions in Tibet. The average annual rainfall on the south slopes varies between 60 inches (1,530 mm) at Shimla, Himachal Pradesh, and Mussoorie, Uttarakhand, in the western Himalayas and 120 inches (3,050 mm) at Darjeeling, West Bengal state, in the eastern Himalayas. North of the Great Himalayas, at places such as Skardu, Gilgit, and Leh in the Ladakh portion of the Indus valley, only 3 to 6 inches (75 to 150 mm) of precipitation occur.

Local relief and location determine climatic variation not only in different parts of the Himalayas but even on different slopes of the same range. Because of its favorable location on top of the Mussoorie Range facing the Dehra Dun, the town of Mussoorie, for example, at an elevation of about 6,100 feet (1,900 meters), receives 92 inches (2,335 mm) of precipitation annually, compared with 62 inches (1,575 mm) in the town of Shimla, which lies some 90 miles (145 km) to the northwest behind a series of ridges reaching 6,600 feet (2,000 meters). The eastern Himalayas, which are at a lower latitude than the western Himalayas, are relatively warmer. The average minimum temperature for the month of May, recorded in Darjeeling at an elevation of 6,380 feet (1,945 meters), is 52 °F (11 °C). In the same month, at an elevation of 16,500 feet (5,000 meters) in the neighborhood of Mount Everest, the minimum temperature is about 17 °F (−8 °C); at 19,500 feet (6,000 meters) it falls to −8 °F (−22 °C), the lowest minimum having been −21 °F (−29 °C); during the day, in areas sheltered from strong winds that often blow at more than 100 miles (160 km) per hour, the sun is often pleasantly warm, even at high elevations.

There are two periods of precipitation: the moderate amounts brought by winter storms and the heavier precipitation of summer, with its southwesterly monsoon winds. During winter, low-pressure weather systems advance into the Himalayas from the west and cause heavy snowfall. Within the regions where western disturbances are felt, condensation occurs in upper air levels, and, as a result, precipitation is much greater over the high mountains. During that season snow accumulates around the Himalayan high peaks, and precipitation is greater in the west than the east. In January, for example, Mussoorie in the west receives almost 3 inches (75 mm), whereas Darjeeling to the east receives less than 1 inch (25 mm). By the end of May the meteorological conditions have reversed. Southwesterly monsoon currents channel moist air toward the eastern Himalayas, where the moisture rising over the steep terrain cools and condenses to fall as rain or snow; in June, therefore, Darjeeling receives about 24 inches (600 mm) and Mussoorie less than 8 inches (200 mm). The rain and snow cease in September, after which the finest weather in the Himalayas prevails until the beginning of winter in December.

Plant life

Himalayan vegetation can be broadly classified into four types—tropical, subtropical, temperate, and alpine—each of which prevails in a zone determined mainly by elevation and precipitation. Local differences in relief and climate, as well as exposure to sunlight and wind, cause considerable variation in the species present within each zone. Tropical evergreen rainforest is confined to the humid foothills of the eastern and central Himalayas. The evergreen dipterocarps—a group of timber- and resin-producing trees—are common; their different species grow on different soils and on hill slopes of varying steepness. Ceylon ironwood (Mesua ferrea) is found on porous soils at elevations between 600 and 2,400 feet (180 and 720 meters); bamboos grow on steep slopes; oaks (genus Quercus) and Indian horse chestnuts (Aesculus indica) grow on the lithosol (shallow soils consisting of imperfectly weathered rock fragments), covering sandstones from Arunachal Pradesh westward to central Nepal at elevations from 3,600 to 5,700 feet (1,100 to 1,700 meters). Alder trees (genus Alnus) are found along the watercourses on the steeper slopes. At higher elevations those species give way to mountain forests in which the typical evergreen is the Himalayan screw pine (Pandanus furcatus). Besides those trees, some 4,000 species of flowering plants, of which 20 are palms, are estimated to occur in the eastern Himalayas.

With decreasing precipitation and increasing elevation westward, the rainforests give way to tropical deciduous forests, where the valuable timber tree sal (Shorea robusta) is the dominant species. Wet sal forests thrive on high plateaus at elevations of about 3,000 feet (900 meters), while dry sal forests prevail higher up, at 4,500 feet (1,400 meters). Farther west, steppe forest (i.e., expanse of grassland dotted with trees), steppe, subtropical thorn steppe, and subtropical semidesert vegetation occur successively. Temperate mixed forests extend from about 4,500 to roughly 11,000 feet (1,400 to 3,400 meters) and contain conifers and broad-leaved temperate trees. Evergreen forests of oaks and conifers have their westernmost outpost on the hills above Murree, some 30 miles (50 km) northwest of Rawalpindi, in Pakistan; those forests are typical of the Lesser Himalayas, being conspicuous on the outer slopes of the Pir Panjal, in Jammu and Kashmir union territory. Chir pine (Pinus roxburghii) is the dominant species at elevations from 2,700 to 5,400 feet (800 to 1,600 meters). In the inner valleys that species may occur even up to 6,300 feet (1,900 meters). Deodar cedar (Cedrus deodara), a highly valued endemic species, grows mainly in the western part of the range. Stands of that species occur between 6,300 and 9,000 feet (1,900 and 2,700 meters) and tend to grow at still higher elevations in the upper valleys of the Sutlej and Ganges rivers. Of the other conifers, blue pine (Pinus wallichiana) and morinda spruce (Picea smithiana) first appear between about 7,300 and 10,000 feet (2,200 and 3,000 meters).

The alpine zone begins above the tree line, between elevations of 10,500 and 11,700 feet (3,200 and 3,600 meters), and extends up to about 13,700 feet (4,200 meters) in the western Himalayas and 14,600 feet (4,500 meters) in the eastern Himalayas. In that zone can be found all the wet and moist alpine vegetation. Juniper (genus Juniperus) is widespread, especially on sunny sites, steep and rocky slopes, and drier areas. Rhododendron occurs everywhere but is more abundant in the wetter parts of the eastern Himalayas, where it grows in all sizes from trees to low shrubs. Mosses and lichens grow in shaded areas at lower levels in the alpine zone where the humidity is high; flowering plants are found at high elevations.

Animal life

The fauna of the eastern Himalayas is similar to that of the southern Chinese and Southeast Asian region. Many of those species are primarily found in tropical forests and are only secondarily adapted to the subtropical, mountain, and temperate conditions prevailing at higher elevations and in the drier western areas. The animal life of the western Himalayas, however, has more affinities with that of the Mediterranean, Ethiopian, and Turkmenian regions. The past presence in the region of some African animals, such as giraffes and the hippopotamuses, can be inferred from fossil remains in deposits found in the Siwalik Range. The animal life at elevations above the tree line consists almost exclusively of cold-tolerant endemic species that evolved from the wildlife of the steppes after the uplift of the Himalayas. Elephants and rhinoceroses are restricted to parts of the forested Tarai region—moist or marshy areas, now largely drained—at the base of the low hills in southern Nepal. Asiatic black bears, clouded leopards, langurs (a long-tailed Asian monkey), and Himalayan goat antelopes (e.g., the tahr) are some of the denizens of the Himalayan forests. The Indian rhinoceros was once abundant throughout the foothill zone of the Himalayas but is now endangered, as is the musk deer; both species are dwindling, and few live, other than those in a handful of reserves set up to protect them. The Kashmir stag, or hangul, is near extinction.

In remote sections of the Himalayas, at higher elevations, snow leopards, brown bears, lesser pandas, and Tibetan yaks have limited populations. The yak has been domesticated and is used as a beast of burden in Ladakh. Above the tree line the most numerous animals, however, are diverse types of insects, spiders, and mites, which are the only animal forms that can live as high up as 20,700 feet (6,300 meters).

Fish of the genus Glyptothorax live in most of the Himalayan streams, and the Himalayan water shrew inhabits stream banks. Lizards of the genus Japalura are widely distributed. Typhlops, a genus of blind snake, is common in the eastern Himalayas. The butterflies of the Himalayas are extremely varied and beautiful, especially those in the genus Troides.

Bird life in the Himalayas is equally rich but is more abundant in the east than in the west. In Nepal alone almost 800 species have been observed. Among some of the common Himalayan birds are different species of magpies (including the black-rumped, the blue, and the racket-tailed), titmice, choughs (related to the jackdaw), whistling thrushes, and redstarts. A few strong fliers, such as the lammergeier (bearded vulture), the black-eared kite, and the Himalayan griffon (an Old World vulture), also can be seen. Snow partridges and Cornish choughs are found at elevations of 18,600 feet (5,700 meters).

Of the four principal language families in the Indian subcontinent—Indo-European, Tibeto-Burman, Austroasiatic, and Dravidian—the first two are well represented in the Himalayas. In ancient times, peoples speaking languages from both families mixed in varying proportions in different areas. Their distribution is the result of a long history of penetrations by Central Asian and Iranian groups from the west, Indian peoples from the south, and Asian peoples from the east and north. In Nepal, which constitutes the middle third of the Himalayas, those groups overlapped and intermingled. The penetrations of the lower Himalayas were instrumental to the migrations into and through the river-plain passageways of South Asia.

Generally speaking, the Great Himalayas and the Tethys Himalayas are inhabited by Tibetans and peoples speaking other Tibeto-Burman languages, while the Lesser Himalayas are the home of Indo-European language speakers. Among the latter are the Kashmiri people of the Vale of Kashmir and the Gaddi and Gujari, who live in the hilly areas of the Lesser Himalayas. Traditionally, the Gaddi are a hill people; they possess large flocks of sheep and herds of goats and go down with them from their snowy abode in the Outer Himalayas only in winter, returning again to the highest pastures in June. The Gujari are traditionally a migrating pastoral people who live off their herds of sheep, goats, and a few cattle, for which they seek pasture at various elevations.

The Champa, Ladakhi, Balti, and Dard peoples live to the north of the Great Himalaya Range in the Kashmir Himalayas. The Dard speak Indo-European languages, while the others are Tibeto-Burman speakers. The Champa traditionally lead a nomadic pastoral life in the upper Indus valley. The Ladakhi have settled on terraces and alluvial fans that flank the Indus in the northeastern Kashmir region. The Balti have spread farther down the Indus valley and have adopted Islam.

Other Indo-European speakers are the Kanet in Himachal Pradesh and the Khasi in Uttarakhand. In Himachal Pradesh most people in the districts of Kalpa and Lahul-Spiti are the descendants of migrants from Tibet who speak Tibeto-Burman languages.

In Nepal the Pahari, speaking Indo-European languages, constitute the majority of the population, although large groups of Tibeto-Burman speakers are found throughout the country. They include the Newar, the Tamang, the Gurung, the Magar, the Sherpa and other peoples related to the Bhutia, and the Kirat. The Kirat were the earliest inhabitants of the Kathmandu Valley. The Newar are also one of the earliest groups in Nepal. The Tamang inhabit the high valleys to the northwest, north, and east of Kathmandu Valley. The Gurung live on the southern slopes of the Annapurna massif, pasturing their cattle as high as 12,000 feet (3,700 meters). The Magar inhabit western Nepal but migrate seasonally to other parts of the country. The Sherpa, who live to the south of Mount Everest, are famed mountaineers.

For some 200 years the Sikkim region (now a state in India) and the kingdom of Bhutan have been safety valves for the absorption of the excess population of eastern Nepal. More Sherpa now live in the Darjeeling area than in the Mount Everest homeland. At present the Pahari constitute the majority who come from Nepal in both Sikkim and Bhutan. Thus, the people of Sikkim belong to three distinct ethnic groups—the Lepcha, the Bhutia, and the Pahari. Generally speaking, the Nepalese and the Lepcha live in western Bhutan and the Bhutia of Tibetan origin in eastern Bhutan.

Arunachal Pradesh is the homeland of several groups—the Abor or Adi, the Aka, the Apa Tani, the Dafla, the Khampti, the Khowa, the Mishmi, the Momba, the Miri, and the Singpho. Linguistically, they are Tibeto-Burman. Each group has its homeland in a distinct river valley, and all practice shifting cultivation (i.e., they grow crops on a different tract of land each year).

Economy of the Himalayas:

Resources

Economic conditions in the Himalayas partly depend on the limited resources available in different parts of that vast region of varied ecological zones. The principal activity is animal husbandry, but forestry, trade, and tourism are also important. The Himalayas abound in economic resources. Those include pockets of rich arable land, extensive grasslands and forests, workable mineral deposits, easy-to-harness waterpower, and great natural beauty. The most productive arable lands in the western Himalayas are in the Vale of Kashmir, the Kangra valley, the Sutlej River basin, and the terraces flanking the Ganges and Yamuna rivers in Uttarakhand; those areas produce rice, corn (maize), wheat, and millet. In the central Himalayas in Nepal, two-thirds of the arable land is in the foothills and on the adjacent plains; that land yields most of the total rice production of the country. The region also produces large crops of corn, wheat, potatoes, and sugarcane.

Most of the fruit orchards of the Himalayas lie in the Vale of Kashmir and in the Kullu valley of Himachal Pradesh. Fruits such as apples, peaches, pears, and cherries—for which there is a great demand in the cities of India—are grown extensively. On the shores of Dal Lake in Kashmir, there are rich vineyards that produce grapes used to make wine and brandy. On the hills surrounding the Vale of Kashmir grow walnut and almond trees. Bhutan also has fruit orchards and exports oranges to India.

Tea is grown in plantations mainly on the hills and on the plain at the foot of the mountains in the Darjeeling district. Plantations also produce limited amounts of tea in the Kangra valley. Plantations of the spice cardamom are to be found in Sikkim, Bhutan, and the Darjeeling Hills. Medicinal herbs are grown on plantations in areas of Uttarakhand.

Transhumance (the seasonal migration of livestock) is widely practiced in the Himalayan pastures. Sheep, goats, and yaks are raised on the rough grazing lands available. During summer they graze on the pastures at higher elevations, but when the weather turns cold, shepherds migrate with their flocks to lower elevations.

The explosive population growth that has occurred in the Himalayas and elsewhere in the Indian subcontinent since the 1940s has placed great stress on the forests in many areas. Deforestation to clear land for planting and to supply firewood, paper, and construction materials has progressed up steeper and higher slopes of the Lesser Himalayas, triggering environmental degradation. Only in Sikkim and Bhutan are large areas still heavily forested.

The Himalayas are rich in minerals, although exploitation is restricted to the more accessible areas. The Kashmir region has the greatest concentration of minerals. Sapphires are found in the Zanskar Range, and alluvial gold is recovered in the nearby bed of the Indus River. There are deposits of copper ore in Baltistan, and iron ores are found in the Vale of Kashmir. Ladakh possesses borax and sulfur deposits. Coal seams are found in the Jammu Hills. Bauxite also occurs in Kashmir. Nepal, Bhutan, and Sikkim have extensive deposits of coal, mica, gypsum, and graphite and ores of iron, copper, lead, and zinc.

The Himalayan rivers have a tremendous potential for hydroelectric generation. That potential was first harnessed intensively by India beginning in the 1950s. A giant multipurpose project is located at Bhakra-Nangal on the Sutlej River in the Outer Himalayas; its reservoir was completed in 1963 and has a storage capacity of some 348 billion cubic feet (10 billion cubic meters) of water and a total installed generating capacity of 1,050 megawatts. Other Himalayan rivers—including the Kosi, the Gandak (Narayani), and the Jaldhaka—were then harnessed by India, which then supplied electric power to Nepal and Bhutan. Subsequent major projects in India included the Nathpa Jhakri dam on the Sutlej in Himachal Pradesh and, just downstream from that site, the Rampur station, which became operational in 2014. Nepal has also constructed hydropower projects in the Himalayas, as has China, which completed the Zangmu station on the Yarlung Zangbo (Brahmaputra) River in Tibet in 2015.

Tourism has become an increasingly important source of income and employment in parts of the Himalayas, especially Nepal. In addition to sightseers, there has been a dramatic rise in the number of foreign trekkers in the lower mountain elevations, as well as in mountaineers seeking to climb Everest and the other high peaks. The resultant increased traffic and tourists’ heavy consumption of the region’s limited resources, however, have further stressed the regional environment.

Transportation

Trails and footpaths long were the only means of communication in the Himalayas. Although those continue to be important, especially in the more remote locations, road transport now has made the Himalayas accessible from both north and south. In Nepal an east-west highway stretches through the Tarai lowlands, connecting roads that penetrate into many of the country’s mountain valleys. The capital, Kathmandu, is connected to Pokhara by a low Himalayan highway, and another highway through Kodari Pass gives Nepal access to Tibet. A highway running from Kathmandu through Hetaunda and Birganj to Birauni connects Nepal to Bihar state and the rest of India. To the northwest in Pakistan, the Karakoram Highway links that country with China. The Hindustan-Tibet road, which passes through Himachal Pradesh, has been considerably improved; that 300-mile (480-km) highway runs through Shimla, once the summer capital of India, and crosses the Indo-Tibetan border near Shipki Pass. From Manali in the Kullu valley, a highway now crosses not only the Great Himalayas but also the Zanskar Range and reaches Leh in the upper Indus valley. Leh is also connected to India via Srinagar in the Vale of Kashmir; the road from Srinagar to Leh passes over the 17,730-foot- (5,404-meter-) high Khardung Pass—the first of the high passes on the historic caravan trail to Central Asia from India. Many other new roads have been built since 1950.

From the Indian state of Punjab the only direct approach to the Vale of Kashmir is by the highway from Jalandhar to Srinagar (summer capital of Jammu and Kashmir union territory) through Pathankot, Jammu, Udhampur, Banihal, and Khahabal. It crosses the Pir Panjal Range through a tunnel at Banihal. The old road from Rawalpindi, Pakistan, to Srinagar lost its importance with the closing of the road at the line of control between the sectors of Kashmir administered by India and Pakistan.

The Sikkim Himalayas command the historic Kalimpang-to-Lhasa caravan trade route, which passes through Gangtok. Before the mid-1950s there was only one 30-mile (50-km) motorable highway running between Gangtok and Rangpo, on the Tista River, which then continued southward another 70 miles (110 km) to Siliguri (Shiliguri) in West Bengal state. Since then, several roads passable by four-wheel-drive vehicles have been built in the southern part of Sikkim, and the highway from Siliguri has been extended through Lachung, in northern Sikkim, to Tibet.

Only two main railroads, both of narrow gauge, penetrate into the Lesser Himalayas from the plains of India: one in the western Himalayas, between Kalka and Shimla, and the other in the eastern Himalayas, between Siliguri and Darjeeling. Another narrow-gauge line in Nepal runs some 30 miles from Raxaul in Bihar state, India, to Amlekhganj. Two other short railroads run to the Outer Himalayas—one, the railroad of the Kullu Valley, from Pathankot to Jogindarnagar and the other from Haridwar to Dehra Dun.

There are two major airstrips in the Himalayas, one at Kathmandu and the other at Srinagar; the airport at Kathmandu is served by international as well as regional flights. Besides those, there are also an increasing number of airstrips of local importance in Nepal and other countries in the region that can accommodate small aircraft. Improvements in both air and ground transportation have facilitated the growth of tourism in the Himalayas.

Study and exploration

The earliest journeys through the Himalayas were undertaken by traders, shepherds, and pilgrims. The pilgrims believed that the harder the journey was, the nearer it brought them to salvation or enlightenment; the traders and shepherds, though, accepted crossing passes as high as 18,000 to 19,000 feet (5,500 to 5,800 meters) as a way of life. For all others, however, the Himalayas constituted a formidable and fearsome barrier.

The first known Himalayan sketch map of some accuracy was drawn up in 1590 by Antonio Monserrate, a Spanish missionary to the court of the Mughal emperor Akbar. In 1733 a French geographer, Jean-Baptiste Bourguignon d’Arville, compiled the first map of Tibet and the Himalayan range based on systematic exploration. In the mid-19th century the Survey of India organized a systematic program to measure correctly the heights of the Himalayan peaks. The Nepal and Uttarakhand peaks were observed and mapped between 1849 and 1855. Nanga Parbat, as well as the peaks of the Karakoram Range to the north, were surveyed between 1855 and 1859. The surveyors did not assign individual names to the innumerable peaks observed but designated them by letters and Roman numerals. Thus, at first Mount Everest was simply labeled as “H”; that had been changed to Peak XV by 1850. In 1865 Peak XV was renamed for Sir George Everest, surveyor general of India from 1830 to 1843. Not until 1852 were the computations sufficiently advanced for it to be realized that Peak XV was higher than any other mountain in the world. By 1862 more than 40 peaks with elevations exceeding 18,000 feet (5,500 meters) had been climbed for surveying purposes.

In addition to the surveying expeditions, various scientific studies of the Himalayas were conducted in the 19th century. Between 1848 and 1849 the English botanist Joseph Dalton Hooker made a pioneering study of the plant life of the Sikkim Himalayas. He was followed by numerous others, including (in the early 20th century) the British naturalist Richard W.G. Hingston, who wrote valuable accounts of the natural history of animals living at high elevations in the Himalayas.

After World War II the Survey of India prepared some large-scale maps of the Himalayas from aerial photographs. Parts of the Himalayas were also mapped by German geographers and cartographers, with the help of ground photogrammetry. In addition, satellite reconnaissance has been employed to produce even more accurate and detailed maps. Aerial photographs have been used in conjunction with other scientific observation methods to monitor the effects of climate change on the Himalayan environment—notably the recession of glaciers.

Himalayan mountaineering began in the 1880s with the Briton W.W. Graham, who claimed to have climbed several peaks in 1883. Though his reports were received with skepticism, they did spark interest in the Himalayas among other European climbers. In the early 20th century the number of mountaineering expeditions increased markedly to the Karakoram Range and to the Kumaun and Sikkim Himalayas. Between World Wars I and II, a certain national preference developed for the various peaks: the Germans concentrated on Nanga Parbat and Kanchenjunga, the Americans on K2 (in the Karakorams), and the British on Mount Everest. Attempts at scaling Everest began in 1921, and about a dozen of them were undertaken before it was first successfully scaled in May 1953 by the New Zealand mountaineer Edmund Hillary and his Tibetan partner Tenzing Norgay. That same year an Austro-German team led by Karl Maria Herrligkoffer reached the summit of Nanga Parbat.

As the high peaks were conquered one by one, climbers began to look for greater challenges to test their skills and equipment. Some attempted to reach the summits by increasingly difficult routes, while others climbed with minimal amounts of gear or without the use of supplemental oxygen at the highest elevations. Easier access to the mountains brought increasingly large numbers of climbers and hikers into the region—hundreds alone trying to summit Everest each year. By the late 20th and early 21st centuries, the annual number of mountaineering expeditions and tourist excursions to the Himalayas was so large that in some areas the participants were threatening the delicate environmental balance of the mountains by destroying plant and animal life and by leaving behind a growing quantity of refuse. In addition, more people in such a highly dangerous environment invited disaster, as was the case in 2014, when more than 40 foreign trekkers perished in a snowstorm near Annapurna.

2430) George Beadle

Gist:

Work

Organisms' metabolism–the chemical processes within its cells–are regulated by substances called enzymes. George Beadle and Edward Tatum proved in 1941 that our genetic code‚ our genes, govern the formation of enzymes. They exposed a type of mold to x-rays, causing mutations, or changes in its genes. They later succeeded in proving that this led to definite changes in enzyme formation. The conclusion was that each enzyme corresponds to a particular gene.

Summary

George Wells Beadle (born Oct. 22, 1903, Wahoo, Neb., U.S.—died June 9, 1989, Pomona, Calif.) was an American geneticist who helped found biochemical genetics when he showed that genes affect heredity by determining enzyme structure. He shared the 1958 Nobel Prize for Physiology or Medicine with Edward Tatum and Joshua Lederberg.

After earning his doctorate in genetics from Cornell University (1931), Beadle went to the laboratory of Thomas Hunt Morgan at the California Institute of Technology, where he did work on the fruit fly, Drosophila melanogaster. Beadle soon realized that genes must influence heredity chemically.

In 1935, with Boris Ephrussi at the Institut de Biologie Physico-Chimique in Paris, he designed a complex technique to determine the nature of these chemical effects in Drosophila. Their results indicated that something as apparently simple as eye colour is the product of a long series of chemical reactions and that genes somehow affect these reactions.

After a year at Harvard University, Beadle pursued gene action in detail at Stanford University in 1937. Working there with Tatum, he found that the total environment of a red bread mold, Neurospora, could be varied in such a way that the researchers could locate and identify genetic changes, or mutants, with comparative ease. They exposed the mold to X rays and studied the altered nutritional requirements of the mutants thus produced. These experiments enabled them to conclude that each gene determined the structure of a specific enzyme that, in turn, allowed a single chemical reaction to proceed. This “one gene–one enzyme” concept won Beadle and Tatum (with Lederberg) the Nobel Prize in 1958.

In addition, the use of genetics to study the biochemistry of microorganisms, outlined in the landmark paper “Genetic Control of Biochemical Reactions in Neurospora” (1941), by Beadle and Tatum, opened up a new field of research with far-reaching implications. Their methods immediately revolutionized the manufacture of penicillin and provided insights into many biochemical processes.

In 1946 Beadle became professor and chairman of the biology division at the California Institute of Technology and served there until 1960, when he was invited to succeed R. Wendel Harrison as chancellor of the University of Chicago; the title of president was reassigned to the position a year later. He retired from the university to direct (1968–70) the American Medical Association’s Institute for Biomedical Research.

His major works include An Introduction to Genetics (1939; with A.H. Sturtevant), Genetics and Modern Biology (1963), and The Language of Life (1966; with Muriel M. Beadle).

Details

George Wells Beadle (October 22, 1903 – June 9, 1989) was an American geneticist. In 1958 he shared one-half of the Nobel Prize in Physiology or Medicine with Edward Tatum for their discovery of the role of genes in regulating biochemical events within cells. He served as the 7th president of the University of Chicago from 1961 to 1968.

Beadle and Tatum's key experiments involved exposing the bread mold Neurospora crassa to x-rays, causing mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways. These experiments led them to propose a direct link between genes and enzymatic reactions, known as the One gene-one enzyme hypothesis.

Education and early life

George Wells Beadle was born in Wahoo, Nebraska. He was the son of Chauncey Elmer Beadle and Hattie Albro, who owned and operated a 40-acre (160,000 sq m) farm nearby.[9] George was educated at the Wahoo High School and might himself have become a farmer if one of his teachers at school had not directed his mind towards science and persuaded him to go to the College of Agriculture in Lincoln, Nebraska. In 1926 he earned his Bachelor of Science degree at the University of Nebraska and subsequently worked for a year with Professor F.D. Keim, who was studying hybrid wheat. In 1927 he earned his Master of Science degree, and Professor Keim secured for him a post as Teaching Assistant at Cornell University, where he worked, until 1931, with Professors R.A. Emerson and L.W. Sharp on Mendelian asynapsis in Zea mays. For this work he obtained, in 1931, his Doctor of Philosophy degree.

Career and research

In 1931 Fellowship at the California Institute of Technology at Pasadena, where he remained from 1931 until 1936. During this period he continued his work on Indian corn and began, in collaboration with Professors Theodosius Dobzhansky, S. Emerson, and Alfred Sturtevant, work on crossing-over in the fruit fly, Drosophila melanogaster.

In 1935 Beadle visited Paris for six months to work with Professor Boris Ephrussi at the Institut de Biologie physico-chimique. Together they began the study of the development of eye pigment in Drosophila which later led to the work on the biochemistry of the genetics of the fungus Neurospora for which Beadle and Edward Lawrie Tatum were together awarded the 1958 Nobel Prize for Physiology or Medicine.

In 1936 Beadle left the California Institute of Technology to become Assistant Professor of Genetics at Harvard University. A year later he was appointed Professor of Biology (Genetics) at Stanford University and there he remained for nine years, working for most of this period in collaboration with Tatum. This work of Beadle and Tatum led to an important generalization. This was that most mutants unable to grow on minimal medium, but able to grow on “complete” medium, each require addition of only one particular supplement for growth on minimal medium. If the synthesis of a particular nutrient (such as an amino acid or vitamin) was disrupted by mutation, that mutant strain could be grown by adding the necessary nutrient to the minimal medium. This finding suggested that most mutations affected only a single metabolic pathway. Further evidence obtained soon after the initial findings tended to show that generally only a single step in the pathway is blocked. Following their first report of three such auxotroph mutants in 1941, Beadle and Tatum used this method to create series of related mutants and determined the order in which amino acids and some other metabolites were synthesized in several metabolic pathways. The obvious inference from these experiments was that each gene mutation affects the activity of a single enzyme. This led directly to the one gene-one enzyme hypothesis, which, with certain qualifications and refinements, has remained essentially valid to the present day. As recalled by Horowitz, the work of Beadle and Tatum also demonstrated that genes have an essential role in biosynthesis. At the time of the experiments (1941), non-geneticists still generally believed that genes governed only trivial biological traits, such as eye color, and bristle arrangement in fruit flies, while basic biochemistry was determined in the cytoplasm by unknown processes. Also, many respected geneticists thought that gene action was far too complicated to be resolved by any simple experiment. Thus Beadle and Tatum brought about a fundamental revolution in our understanding of genetics.

In 1946 Beadle returned to the California Institute of Technology as Professor of Biology and Chairman of the Division of Biology. Here he remained until January 1961 when he was elected Chancellor of the University of Chicago and, in the autumn of the same year, President of this university.

After retiring, Beadle undertook a remarkable experiment in maize genetics. In several laboratories he grew a series of Teosinte/Maize crosses. Then he crossed these progeny with each other. He looked for the rate of appearance of parent phenotypes among this second generation. The vast majority of these plants were intermediate between maize and Teosinte in their features, but about 1 in 500 of the plants were identical to either the parent maize or the parent teosinte. Using the mathematics of Mendelian genetics, he calculated that this showed a difference between maize and teosinte of about 5 or 6 genetic loci. This demonstration was so compelling that most scientists now agree that Teosinte is the wild progenitor of maize.

During his career, Beadle received many honors. These included honorary Doctor of Science degrees from Yale (1947), Nebraska (1949), Northwestern University (1952), Rutgers University (1954), Kenyon College (1955), Wesleyan University (1956), the University of Birmingham and the University of Oxford, England (1959), Pomona College (1961), and Lake Forest College (1962). In 1962 he was also given the honorary degree of LL.D. by the University of California, Los Angeles. He was elected a Fellow of the American Academy of Arts and Sciences in 1946.[15] He also received the Lasker Award of the American Public Health Association (1950), the Dyer Award (1951), the Emil Christian Hansen Prize of Denmark (1953), the Albert Einstein Commemorative Award in Science (1958), the Nobel Prize in Physiology or Medicine 1958 with Edward Tatum and Joshua Lederberg, the National Award of the American Cancer Society (1959), and the Kimber Genetics Award of the National Academy of Sciences (1960).

Hi,

Good work!

2703.

Hi,

#10741. What does the term in Biology Founder effect mean?

#10742. What does the term in Biology Fungus mean?

Hi,

#2565. What does the medical term Hyperbaric medicine mean?

Hi,

#6344.

Hi,

Correct!

2701.

2429) Fredrick Sanger

Gist:

Life

Frederick Sanger was born in the small village of Rendcomb, England. His father was a doctor. After having converted to quakerism he brought up his sons as quakers. Frederick Sanger studied and received his PhD at the University of Cambridge in 1943. He remained in Cambridge for the rest of his career. Frederick Sanger was married with three children.

Work

Proteins, which are molecules made up of chains of amino acids, play a pivotal role in life processes in our cells. One important protein is insulin, a hormone that regulates sugar content in blood. Beginning in the 1940s, Frederick Sanger studied the composition of the insulin molecule. He used acids to break the molecule into smaller parts, which were separated from one another with the help of electrophoresis and chromatography. Further analyses determined the amino acid sequences in the molecule’s two chains, and in 1955 Sanger identified how the chains are linked together.

Summary

Frederick Sanger (born August 13, 1918, Rendcombe, Gloucestershire, England—died November 19, 2013, Cambridge) was an English biochemist who was twice the recipient of the Nobel Prize for Chemistry. He was awarded the prize in 1958 for his determination of the structure of the insulin molecule. He shared the prize (with Paul Berg and Walter Gilbert) in 1980 for his determination of base sequences in nucleic acids. Sanger was the fourth two-time recipient of the Nobel Prize.

Education

Sanger was the middle child of Frederick Sanger, a medical practitioner, and Cicely Crewsdon Sanger, the daughter of a wealthy cotton manufacturer. The family expected him to follow in his father’s footsteps and become a medical doctor. After much thought, he decided to become a scientist. In 1936 Sanger entered St. John’s College, Cambridge. He initially concentrated on chemistry and physics, but he was later attracted to the new field of biochemistry. He received a bachelor’s degree in 1939 and stayed at Cambridge an additional year to take an advanced course in biochemistry. He and Joan Howe married in 1940 and subsequently had three children.

Because of his Quaker upbringing, Sanger was a conscientious objector and was assigned as an orderly to a hospital near Bristol when World War II began. He soon decided to visit Cambridge to see if he could enter the doctoral program in biochemistry. Several researchers there were interested in having a student, especially one who did not need money. He studied lysine metabolism with biochemist Albert Neuberger. They also had a project in support of the war effort, analyzing nitrogen from potatoes. Sanger received a doctorate in 1943.

Insulin research

Biochemist Albert C. Chibnall and his protein research group moved from Imperial College in London to the safer wartime environment of the biochemistry department at Cambridge. Two schools of thought existed among protein researchers at the time. One group thought proteins were complex mixtures that would not readily lend themselves to chemical analysis. Chibnall was in the other group, which considered a given protein to be a distinct chemical compound.

Chibnall was studying insulin when Sanger joined the group. At Chibnall’s suggestion, Sanger set out to identify and quantify the free-amino groups of insulin. Sanger developed a method using dinitrofluorobenzene to produce yellow-coloured derivatives of amino groups (see amino acid). Information about a new separation technique, partition chromatography, had recently been published. In a pattern that typified Sanger’s career, he immediately recognized the utility of the new technique in separating the hydrolysis products of the treated protein. He identified two terminal amino groups for insulin, phenylalanine and glycine, suggesting that insulin is composed of two types of chains. Working with his first graduate student, Rodney Porter, Sanger used the method to study the amino terminal groups of several other proteins. (Porter later shared the 1972 Nobel Prize for Physiology or Medicine for his work in determining the chemical structure of antibodies.)

On the assumption that insulin chains are held together by disulphide linkages, Sanger oxidized the chains and separated two fractions. One fraction had phenylalanine at its amino terminus; the other had glycine. Whereas complete acid hydrolysis degraded insulin to its constituent amino acids, partial acid hydrolysis generated insulin peptides composed of several amino acids. Using another recently introduced technique, paper chromatography, Sanger was able to sequence the amino-terminal peptides of each chain, demonstrating for the first time that a protein has a specific sequence at a specific site. A combination of partial acid hydrolysis and enzymatic hydrolysis allowed Sanger and the Austrian biochemist Hans Tuppy to determine the complete sequence of amino acids in the phenylalanine chain of insulin. Similarly, Sanger and the Australian biochemist E.O.P. Thompson determined the sequence of the glycine chain.

Two problems remained: the distribution of the amide groups and the location of the disulphide linkages. With the completion of those two puzzles in 1954, Sanger had deduced the structure of insulin. For being the first person to sequence a protein, Sanger was awarded the 1958 Nobel Prize for Chemistry.

Sanger and his coworkers continued their studies of insulin, sequencing insulin from several other species and comparing the results. Utilizing newly introduced radiolabeling techniques, Sanger mapped the amino acid sequences of the active centres from several enzymes. One of these studies was conducted with another graduate student, Argentine-born immunologist César Milstein. (Milstein later shared the 1984 Nobel Prize for Physiology or Medicine for discovering the principle for the production of monoclonal antibodies.)

RNA research

In 1962 the Medical Research Council opened its new laboratory of molecular biology in Cambridge. The Austrian-born British biochemist Max Perutz, British biochemist John Kendrew, and British biophysicist Francis Crick moved to the new laboratory. Sanger joined them as head of the protein division. It was a banner year for the group, as Perutz and Kendrew shared the 1962 Nobel Prize for Chemistry and Crick shared the 1962 Nobel Prize for Physiology or Medicine with the American geneticist James D. Watson and the New Zealand-born British biophysicist Maurice Wilkins for the discovery of DNA (deoxyribonucleic acid).

Sanger’s interaction with nucleic acid groups at the new laboratory led to his pursuing studies on ribonucleic acid (RNA). RNA molecules are much larger than proteins, so obtaining molecules small enough for technique development was difficult. The American biochemist Robert W. Holley and his coworkers were the first to sequence RNA when they sequenced alanine-transfer RNA. They used partial hydrolysis methods somewhat like those Sanger had used for insulin. Unlike other RNA types, transfer RNAs have many unusual nucleotides. This partial hydrolysis method would not work well with other RNA molecules, which contain only four types of nucleotides, so a new strategy was needed.

The goal of Sanger’s lab was to sequence a messenger RNA and determine the genetic code, thereby solving the puzzle of how groups of nucleotides code for amino acids. Working with British biochemists George G. Brownlee and Bart G. Barrell, Sanger developed a two-dimensional electrophoresis method for sequencing RNA. By the time the sequence methods were worked out, the code had been broken by other researchers, mainly the American biochemist Marshall Nirenberg and the Indian-born American biochemist Har Gobind Khorana, using in vitro protein synthesis techniques. The RNA sequence work of Sanger’s group did confirm the genetic code.

DNA research

By the early 1970s Sanger was interested in deoxyribonucleic acid (DNA). DNA sequence studies had not developed because of the immense size of DNA molecules and the lack of suitable enzymes to cleave DNA into smaller pieces. Building on the enzyme copying approach used by the Swiss chemist Charles Weissmann in his studies on bacteriophage RNA, Sanger began using the enzyme DNA polymerase to make new strands of DNA from single-strand templates, introducing radioactive nucleotides into the new DNA. DNA polymerase requires a primer that can bind to a known region of the template strand. Early success was limited by the lack of suitable primers. Sanger and British colleague Alan R. Coulson developed the “plus and minus” method for rapid DNA sequencing. It represented a radical departure from earlier methods in that it did not utilize partial hydrolysis. Instead, it generated a series of DNA molecules of varying lengths that could be separated by using polyacrylamide gel electrophoresis. For both plus and minus systems, DNA was synthesized from templates to generate random sets of DNA molecules from very short to very long. When both plus and minus sets were separated on the same gel, the sequence could be read from either system, one confirming the other. In 1977 Sanger’s group used this system to deduce most of the DNA sequence of bacteriophage ΦX174, the first complete genome to be sequenced.

A few problems remained with the plus and minus system. Sanger, Coulson, and British colleague Steve Nicklen developed a similar procedure using dideoxynucleotide chain-terminating inhibitors. DNA was synthesized until an inhibitor molecule was incorporated into the growing DNA chain. Using four reactions, each with a different inhibitor, sets of DNA fragments were generated ending in every nucleotide. For example, in the A reaction, a series of DNA fragments ending in A (adenine) was generated. In the C reaction, a series of DNA fragments ending in C (cytosine) was generated, and so on for G (guanine) and T (thymine). When the four reactions were separated side by side on a gel and an autoradiograph developed, the sequence was read from the film. Sanger and his coworkers used the dideoxy method to sequence human mitochondrial DNA. For his contributions to DNA sequencing methods, Sanger shared the 1980 Nobel Prize for Chemistry. He retired in 1983.

Additional Honors

Sanger’s additional honours included election as a fellow of the Royal Society (1954), being named a Commander of the Order of the British Empire (CBE; 1963), receiving the Royal Society’s Royal Medal (1969) and Copley Medal (1977), and election to the Order of the Companions of Honour (CH; 1981) and the Order of Merit (OM; 1986). In 1993 the Wellcome Trust and the British Medical Research Council established a genome research centre, honouring Sanger by naming it the Wellcome Trust Sanger Institute.

Details

Frederick Sanger (13 August 1918 – 19 November 2013) was a British biochemist who received the Nobel Prize in Chemistry twice.

He won the 1958 Chemistry Prize for determining the amino acid sequence of insulin and numerous other proteins, demonstrating in the process that each had a unique, definite structure; this was a foundational discovery for the central dogma of molecular biology.

At the newly constructed Laboratory of Molecular Biology in Cambridge, he developed and subsequently refined the first-ever DNA sequencing technique, which vastly expanded the number of feasible experiments in molecular biology and remains in widespread use today. The breakthrough earned him the 1980 Nobel Prize in Chemistry, which he shared with Walter Gilbert and Paul Berg.

He is one of only three people to have won multiple Nobel Prizes in the same category (the others being John Bardeen in physics and Karl Barry Sharpless in chemistry), and one of five persons with two Nobel Prizes.

Early life and education

Frederick Sanger was born on 13 August 1918 in Rendcomb, a small village in Gloucestershire, England, the second son of Frederick Sanger, a general practitioner, and his wife, Cicely Sanger (née Crewdson). He was one of three children. His brother, Theodore, was only a year older, while his sister May (Mary) was five years younger. His father had worked as an Anglican medical missionary in China but returned to England because of ill health. He was 40 in 1916 when he married Cicely, who was four years younger. Sanger's father converted to Quakerism soon after his two sons were born and brought up the children as Quakers. Sanger's mother was the daughter of an affluent cotton manufacturer and had a Quaker background, but was not a Quaker.

When Sanger was around five years old the family moved to the small village of Tanworth-in-Arden in Warwickshire. The family was reasonably wealthy and employed a governess to teach the children. In 1927, at the age of nine, he was sent to the Downs School, a residential preparatory school run by Quakers near Malvern. His brother Theo was a year ahead of him at the same school. In 1932, at the age of 14, he was sent to the recently established Bryanston School in Dorset. This used the Dalton system and had a more liberal regime which Sanger much preferred. At the school he liked his teachers and particularly enjoyed scientific subjects. Able to complete his School Certificate a year early, for which he was awarded seven credits, Sanger was able to spend most of his last year of school experimenting in the laboratory alongside his chemistry master, Geoffrey Ordish, who had originally studied at Cambridge University and been a researcher in the Cavendish Laboratory. Working with Ordish made a refreshing change from sitting and studying books and awakened Sanger's desire to pursue a scientific career. In 1935, prior to heading off to college, Sanger was sent to Schule Schloss Salem in southern Germany on an exchange program. The school placed a heavy emphasis on athletics, which caused Sanger to be much further ahead in the course material compared to the other students. He was shocked to learn that each day was started with readings from Hitler's Mein Kampf, followed by a Sieg Heil salute.

In 1936 Sanger went to St John's College, Cambridge, to study natural sciences. His father had attended the same college. For Part I of his Tripos he took courses in physics, chemistry, biochemistry and mathematics but struggled with physics and mathematics. Many of the other students had studied more mathematics at school. In his second year he replaced physics with physiology. He took three years to obtain his Part I. For his Part II he studied biochemistry and obtained a 1st Class Honours. Biochemistry was a relatively new department founded by Gowland Hopkins with enthusiastic lecturers who included Malcolm Dixon, Joseph Needham and Ernest Baldwin.

Both his parents died from cancer during his first two years at Cambridge. His father was 60 and his mother was 58. As an undergraduate Sanger's beliefs were strongly influenced by his Quaker upbringing. He was a pacifist and a member of the Peace Pledge Union. It was through his involvement with the Cambridge Scientists' Anti-War Group that he met his future wife, Joan Howe, who was studying economics at Newnham College. They courted while he was studying for his Part II exams and married after he had graduated in December 1940. Sanger, although brought up and influenced by his religious upbringing, later began to lose sight of his Quaker related ways. He began to see the world through a more scientific lens, and with the growth of his research and scientific development he slowly drifted farther from the faith he grew up with. He had nothing but respect for the religious and states he took two things from it, truth and respect for all life. Under the Military Training Act 1939 he was provisionally registered as a conscientious objector, and again under the National Service (Armed Forces) Act 1939, before being granted unconditional exemption from military service by a tribunal. In the meantime he undertook training in social relief work at the Quaker centre, Spicelands, Devon and served briefly as a hospital orderly.

Sanger began studying for a PhD in October 1940 under N.W. "Bill" Pirie. His project was to investigate whether edible protein could be obtained from grass. After little more than a month Pirie left the department and Albert Neuberger became his adviser. Sanger changed his research project to study the metabolism of lysine and a more practical problem concerning the nitrogen of potatoes. His thesis had the title, "The metabolism of the amino acid lysine in the animal body". He was examined by Charles Harington and Albert Charles Chibnall and awarded his doctorate in 1943.

2491) Red Sea

Gist

The Red Sea is a vital 2,250 km long, 355 km wide, and up to 2,730 m deep, narrow, and hypersaline inlet of the Indian Ocean, positioned between Northeast Africa and the Arabian Peninsula. As a crucial, warm-water maritime trade route (carrying 12%) of global trade) connected via the Suez Canal and Bab-el-Mandeb Strait, it separates countries like Egypt, Sudan, and Eritrea from Saudi Arabia and Yemen. 

The Red Sea is known for its vital trade route (Suez Canal), incredibly rich biodiversity with vibrant coral reefs and unique marine life, extremely warm and salty water, year-round sunshine, and significant historical/religious importance, particularly the biblical story of Moses. It's a major global hotspot for scuba diving and snorkeling due to its clear waters and abundant fish species.

Summary

The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To the north of the Red Sea lies the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez, which leads to the Suez Canal. It is underlain by the Red Sea Rift, which is part of the Great Rift Valley.

The Red Sea has a surface area of roughly 438,000 sq km (169,000 sq mi), is about 2,250 km (1,400 mi) long, and 355 km (221 mi) across at its widest point. It has an average depth of 490 m (1,610 ft), and in the central Suakin Trough, it reaches its maximum depth of 2,730 m (8,960 ft).

The Red Sea is quite shallow, with approximately 40% of its area being less than 100 m (330 ft) deep, and approximately 25% being less than 50 m (160 ft) deep. The extensive shallow shelves are noted for their marine life and corals. More than 1,000 invertebrate species and 200 types of soft and hard coral live in the sea. The Red Sea is the world's northernmost tropical sea and has been designated a Global 200 ecoregion.

Details

Red Sea is a narrow strip of water extending southeastward from Suez, Egypt, for about 1,200 miles (1,930 km) to the Bab el-Mandeb Strait, which connects with the Gulf of Aden and thence with the Arabian Sea. Geologically, the Gulfs of Suez and Aqaba (Elat) must be considered as the northern extension of the same structure. The sea separates the coasts of Egypt, Sudan, and Eritrea to the west from those of Saudi Arabia and Yemen to the east. Its maximum width is 190 miles, its greatest depth 9,974 feet (3,040 metres), and its area approximately 174,000 square miles (450,000 square km).

The Red Sea contains some of the world’s hottest and saltiest seawater. With its connection to the Mediterranean Sea via the Suez Canal, it is one of the most heavily traveled waterways in the world, carrying maritime traffic between Europe and Asia. Its name is derived from the colour changes observed in its waters. Normally, the Red Sea is an intense blue-green; occasionally, however, it is populated by extensive blooms of the algae Trichodesmium erythraeum, which, upon dying off, turn the sea a reddish brown colour.

The following discussion focuses on the Red Sea and the Gulfs of Suez and Aqaba.

Physical features:

Physiography and submarine morphology

The Red Sea lies in a fault depression that separates two great blocks of Earth’s crust—Arabia and North Africa. The land on either side, inland from the coastal plains, reaches heights of more than 6,560 feet above sea level, with the highest land in the south.

At its northern end the Red Sea splits into two parts, the Gulf of Suez to the northwest and the Gulf of Aqaba to the northeast. The Gulf of Suez is shallow—approximately 180 to 210 feet deep—and it is bordered by a broad coastal plain. The Gulf of Aqaba, on the other hand, is bordered by a narrow plain, and it reaches a depth of 5,500 feet. From approximately 28° N, where the Gulfs of Suez and Aqaba converge, south to a latitude near 25° N, the Red Sea’s coasts parallel each other at a distance of roughly 100 miles apart. There the seafloor consists of a main trough, with a maximum depth of some 4,000 feet, running parallel to the shorelines.

South of this point and continuing southeast to latitude 16° N, the main trough becomes sinuous, following the irregularities of the shoreline. About halfway down this section, roughly between 20° and 21° N, the topography of the trough becomes more rugged, and several sharp clefts appear in the seafloor. Because of an extensive growth of coral banks, only a shallow narrow channel remains south of 16° N. The sill (submarine ridge) separating the Red Sea and the Gulf of Aden at the Bab el-Mandeb Strait is affected by this growth; therefore, the depth of the water is only about 380 feet, and the main channel becomes narrow.

The clefts within the deeper part of the trough are unusual seafloor areas in which hot brine concentrates are found. These patches apparently form distinct and separated deeps within the trough and have a north-south trend, whereas the general trend of the trough is from northwest to southeast. At the bottom of these areas are unique sediments, containing deposits of heavy metal oxides from 30 to 60 feet thick.

Most of the islands of the Red Sea are merely exposed reefs. There is, however, a group of active volcanoes just south of the Dahlak Archipelago (15° 50′ N), as well as a recently extinct volcano on the island of Jabal Al-Ṭāʾir.

Geology

The Red Sea occupies part of a large rift valley in the continental crust of Africa and Arabia. This break in the crust is part of a complex rift system that includes the East African Rift System, which extends southward through Ethiopia, Kenya, and Tanzania for almost 2,200 miles and northward for more than 280 miles from the Gulf of Aqaba to form the great Wadi Aqaba–Dead Sea–Jordan Rift; the system also extends eastward for 600 miles from the southern end of the Red Sea to form the Gulf of Aden.

The Red Sea valley cuts through the Arabian-Nubian Massif, which was a continuous central mass of Precambrian igneous and metamorphic rocks (i.e., formed deep within the Earth under heat and pressure more than 540 million years ago), the outcrops of which form the rugged mountains of the adjoining region. The massif is surrounded by these Precambrian rocks overlain by Paleozoic marine sediments (542 to 251 million years old). These sediments were affected by the folding and faulting that began late in the Paleozoic; the laying down of deposits, however, continued to occur during this time and apparently continued into the Mesozoic Era (251 to 65.5 million years ago). The Mesozoic sediments appear to surround and overlap those of the Paleozoic and are in turn surrounded by early Cenozoic sediments (i.e., between 65.5 and 55.8 million years old). In many places large remnants of Mesozoic sediments are found overlying the Precambrian rocks, suggesting that a fairly continuous cover of deposits once existed above the older massif.

The Red Sea is considered a relatively new sea, whose development probably resembles that of the Atlantic Ocean in its early stages. The Red Sea’s trough apparently formed in at least two complex phases of land motion. The movement of Africa away from Arabia began about 55 million years ago. The Gulf of Suez opened up about 30 million years ago, and the northern part of the Red Sea about 20 million years ago. The second phase began about 3 to 4 million years ago, creating the trough in the Gulf of Aqaba and also in the southern half of the Red Sea valley. This motion, estimated as amounting to 0.59 to 0.62 inch (15.0 to 15.7 mm) per year, is still proceeding, as indicated by the extensive volcanism of the past 10,000 years, by seismic activity, and by the flow of hot brines in the trough.

Climate

The Red Sea region receives very little precipitation in any form, although prehistoric artifacts indicate that there were periods with greater amounts of rainfall. In general, the climate is conducive to outdoor activity in fall, winter, and spring—except during windstorms—with temperatures varying between 46 and 82 °F (8 and 28 °C). Summer temperatures, however, are much higher, up to 104 °F (40 °C), and relative humidity is high, rendering vigorous activity unpleasant. In the northern part of the Red Sea area, extending down to 19° N, the prevailing winds are north to northwest. Best known are the occasional westerly, or “Egyptian,” winds, which blow with some violence during the winter months and generally are accompanied by fog and blowing sand. From latitude 14° to 16° N the winds are variable, but from June through August strong northwest winds move down from the north, sometimes extending as far south as the Bab el-Mandeb Strait; by September, however, this wind pattern retreats to a position north of 16° N. South of 14° N the prevailing winds are south to southeast.

Hydrology

No water enters the Red Sea from rivers, and rainfall is scant; but the evaporation loss—in excess of 80 inches per year—is made up by an inflow through the eastern channel of the Bab el-Mandeb Strait from the Gulf of Aden. This inflow is driven toward the north by prevailing winds and generates a circulation pattern in which these low-salinity waters (the average salinity is about 36 parts per thousand) move northward. Water from the Gulf of Suez has a salinity of about 40 parts per thousand, owing in part to evaporation, and consequently a high density. This dense water moves toward the south and sinks below the less dense inflowing waters from the Red Sea. Below a transition zone, which extends from depths of about 300 to 1,300 feet, the water conditions are stabilized at about 72 °F (22 °C), with a salinity of almost 41 parts per thousand. This south-flowing bottom water, displaced from the north, spills over the sill at Bab el-Mandeb, mostly through the eastern channel. It is estimated that there is a complete renewal of water in the Red Sea every 20 years.

Below this southward-flowing water, in the deepest portions of the trough, there is another transition layer, only 80 feet thick, below which, at some 6,400 feet, lie pools of hot brine. The brine in the Atlantis II Deep has an average temperature of almost 140 °F (60 °C), a salinity of 257 parts per thousand, and no oxygen. There are similar pools of water in the Discovery Deep and in the Chain Deep (at about 21°18′ N). Heating from below renders these pools unstable, so that their contents mix with the overlying waters; they thus become part of the general circulation system of the sea.

Economic aspects:

Resources

Five major types of mineral resources are found in the Red Sea region: petroleum deposits, evaporite deposits (sediments laid down as a result of evaporation, such as halite, sylvite, gypsum, and dolomite), sulfur, phosphates, and the heavy-metal deposits in the bottom oozes of the Atlantis II, Discovery, and other deeps. The oil and natural gas deposits have been exploited to varying degrees by the nations adjoining the sea; of note are the deposits near Jamsah (Gemsa) Promontory (in Egypt) at the juncture of the Gulf of Suez and the Red Sea. Despite their ready availability, the evaporites have been exploited only slightly, primarily on a local basis. Sulfur has been mined extensively since the early 20th century, particularly from deposits at Jamsah Promontory. Phosphate deposits are present on both sides of the sea, but the grade of the ore has been too low to warrant exploitation with existing techniques.

None of the heavy metal deposits have been exploited, although the sediments of the Atlantis II Deep alone have been estimated to be of considerable economic value. The average analysis of the Atlantis II Deep deposit has revealed an iron content of 29 percent; zinc 3.4 percent; copper 1.3 percent; and trace quantities of lead, silver, and gold. The total brine-free sediment estimated to be present in the upper 30 feet of the Atlantis II Deep is about 50 million tons. These deposits appear to extend to a depth of 60 feet below the present sediment surface, but the quality of the deposits below 30 feet is unknown. The sediments of the Discovery Deep and of several other deposits also have significant metalliferous content but at lower concentrations than that in the Atlantis II Deep, and thus they have not been of as much economic interest. The recovery of sediment located beneath 5,700 to 6,400 feet of water poses problems. But since most of these metalliferous deposits are fluid oozes, it is thought to be possible to pump them to the surface in much the same way as oil. There also are numerous proposals for drying and beneficiating (treating for smelting) these deposits after recovery.

Navigation

Navigation in the Red Sea is difficult. The unindented shorelines of the sea’s northern half provide few natural harbours, and in the southern half the growth of coral reefs has restricted the navigable channel and blocked some harbour facilities. At Bab el-Mandeb Strait, the channel is kept open to shipping by blasting and dredging. Atmospheric distortion (heat shimmer), sandstorms, and highly irregular water currents add to the navigational hazards.

Study and exploration

The Red Sea is one of the first large bodies of water mentioned in recorded history. It was important in early Egyptian maritime commerce (2000 bce) and was used as a water route to India by about 1000 bce. It is believed that it was reasonably well-charted by 1500 bce, because at that time Queen Hatshepsut of Egypt sailed its length. Later the Phoenicians explored its shores during their circumnavigatory exploration of Africa in about 600 bce. Shallow canals were dug between the Nile and the Red Sea before the 1st century ce but were later abandoned. A deep canal between the Mediterranean and Red seas was first suggested about 800 ce by the caliph Hārūn al-Rashīd, but it was not until 1869 that the French diplomat Ferdinand de Lesseps oversaw the completion of the Suez Canal connecting the two seas.

The Red Sea was subject to substantial scientific research in the 20th century, particularly since World War II. Notable cruises included those of the Swedish research vessel Albatross (1948) and the American Glomar Challenger (1972). In addition to studying the sea’s chemical and biological properties, researchers focused considerable attention on understanding its geologic structure. Much of the geologic study was in conjunction with oil exploration.

Additional Information

When my friends and family ask me what I am doing in my research, I respond that “I am investigating the winds and currents of the Red Sea in the Middle East.” Scary faces pop up. All they see are the winds of wars—the ever-present terrorist attacks, fighting, and killings in the region. “Are you crazy?” they say.

I get this same question (and sometimes the same reaction) from my oceanography colleagues. Since I began my postdoctoral research at Woods Hole Oceanographic Institution, working with WHOI physical oceanographers Amy Bower and Tom Farrar, I have learned two things: first, that few people realize how beautiful the Middle East is, and second, that the seas there have fascinating and unusual characteristics and far-reaching impacts on life in and around them. These seas furnish moisture for the arid Middle Eastern atmosphere and allowed great civilizations to flourish thousands of years ago around these seas.

For an oceanographer like myself, the Red Sea can be viewed as a mini-ocean, like a toy model ocean. Most of the oceanic features in a big ocean such as the Atlantic, we can also find there.

But the Red Sea also has its own curious characteristics that are not seen in other oceans. It is extremely warm—temperatures in its surface waters reach than 30° Celsius (86° Fahrenheit)—and water evaporates from it at a prodigious rate, making it extremely salty. Because of its narrow confines and constricted connection to the global ocean and because it is subject to seasonal flip-flopping wind patterns governed by the monsoons, it has odd circulation patterns. Its currents change in summer and winter.

The Red Sea is one of the few places on Earth that has what is known as a poleward-flowing eastern boundary current. Eastern boundary currents are so called because they hug the eastern coasts of continents. But all other such eastern boundary currents head south in the northern hemisphere. But the Red Sea Eastern Boundary Current, unlike all others, flows in the direction of the North Pole.

Unravelling the intricate tapestry that creates this rare eastern boundary current in the Red Sea was a goal of my postdoctoral research. But I have found that the Red Sea is far more mesmerizing and complex than I initially imagined. A variety of exotic threads are woven into the tapestry that produce the Red Sea’s unusual oceanographic phenomena: seasonal monsoons, desert sandstorms, wind jets through narrow mountain gaps, the Strait of Bab Al Mandeb that squeezes passage in and out of the sea—even locust swarms.

The politics of the nations surrounding the Red Sea are also complex and make it among the more difficult places to collect data. That explains why many Red Sea phenomena have remained unknown. But unexplored regions are the juiciest for scientists, because they are the ripest places to make new discoveries.

Gateway to the Red Sea

In the Red Sea, the water evaporates at one of the highest rates in the world. Like a bathtub in a steam room, you would have to add water from the tap to keep its water level stable.

The Red Sea compensates for the large water volume it loses each year through evaporation by importing water from the Gulf of Aden—through the narrow Strait of Bab Al Mandeb between Yemen on the Arabian Peninsula and Djibouti and Eritrea on the Horn of Africa.

The Strait of Bab Al Mandeb works as a gate. All waters in and out of the sea must pass through it. No other gates exist, making the Red Sea what is known as a semi-enclosed marginal sea.

In winter, incoming surface waters from the Gulf of Aden flow in a typical western boundary current, hugging the western side of the Red Sea along the coasts of Eritrea and Sudan. The current transports the waters northward. But in the central part of the Red Sea, this current veers sharply to the right. When it reaches the eastern side, it continues its convoluted journey to the north, but now it hugs the eastern side of the sea along coast of Saudi Arabia.

Here’s where the mystery deepens. The Red Sea Eastern Boundary Current exists only in winter. In summer, it’s not there. I wanted to find out how it forms, how it changes, and why it seasonally disappears.

Detectives and pirates

To unravel the complex tapestry that makes the Red Sea Eastern Boundary Current, I am like a CSI (Crime Scene Investigator) agent, sifting through as much data as I can get and putting them together to solve a mystery.

But it’s hard to obtain data from the Red Sea. Its narrow confines mean that its waters are restricted by countries around it that are often in conflict. It’s hard for researchers to get permission to enter them.

In addition, many waters in and enroute to the Red Sea have been beset by piracy. In the spring of 2018, I was aboard of the NOAA ship Ronald H. Brown in the Arabian Sea. It was the first time in more than a decade that the U.S. Navy allowed an American research vessel to go to the Arabian Sea. We were allowed to go only on the eastern side, and we couldn’t go anywhere beyond 17.5° N, because it wasn’t safe. On board, we conducted many safety drills, learning how to hide from pirates.

The Red Sea is also hard for satellites. Its width is small compared with the spatial resolution of most oceanographic satellites. Altimeter and wind satellites have a spatial resolution around 30 to 50 kilometers. The maximum Red Sea width is only 355 kilometers. In addition, satellites can give us information about what happens at the sea surface, but they can’t reveal the mixing and other processes that go on beneath the surface.

That’s why my research was kidnapped and carried off into an unanticipated direction, and my focus shifted from sea to air.

A plague of locusts

In the Red Sea, evaporation is a critical factor driving how the sea operates, and to determine how much water evaporates, we need to know about the winds.   Why? Because evaporation rates depend on the winds. If the winds are stronger, the evaporation is stronger; if the winds are weaker, evaporation is weaker.

To complicate the situation a bit more, evaporation depends not only on the strength of the winds but where the winds are coming from. If the winds are coming over the sea, the air humidity in the winds will be higher, and evaporation will be lower; if the winds are coming from the desert, the air will be dry, and evaporation will be higher.

So, to unravel the Eastern Boundary Current, we needed to have a pretty good picture of how the winds blow in winter. When I started my postdoctoral research, I was really surprised to see that this important factor—the wind variability of the Red Sea—wasn’t well-known, even though interest on it goes way back!

Pioneering studies about winds in the Red Sea were motivated by a desire to determine the northward migration of desert locust swarms that invade areas and voraciously consume all the vegetation in it. This plague has been described in the Old Testament of the Bible and has tormented countries bordering the Red Sea since times immemorial.

The locusts breed along the shores of the Red Sea. Summer monsoon rains spur locust eggs to hatch. When enough rains fall to create plenty of water and vegetation for food, large numbers of locusts hatch and form swarms. Winds determine where the swarms will be carried off to infest neighboring regions.

Lining both sides of the Red Sea are tall mountains that create a kind of tunnel, so that winds blow predominantly along, not across, the Red Sea. In summer, the winds blow from north to south. In winter, however, the monsoon flips the wind direction in the southern part of the Red Sea, andtwo opposing airstreams meet at some point in the central Red Sea called the Red Sea Convergence Zone. It acts as a conduit for migrating locust swarms, and where it is positioned determines where the swarms go.

Mountain-gap wind jets

The mountains along Red Sea coasts affect the winds in another way. The mountains aren’t entirely compact; there are several gaps in them. The tunnel surrounding the Red Sea has a few holes in both sides. Sometimes the winds blow through one of these holes and cross the tunnel. These are the mountain-gap wind jets.

The mountain-gap winds in summer blow from Africa to Saudi Arabia through the Tokar Gap near the Sudanese coast. In winter, the mountain-gap winds blow in the opposite direction, from Saudi Arabia to Africa, through many nameless gaps in the northern part of the Red Sea.

These jets stir up frequent sandstorms carrying sand and dirt from surrounding deserts into the Red Sea. The sandstorms carry fertilizing nutrients that promote life in the Red Sea. The sands also block incoming sunlight and cool the sea surface.

But do these overlooked jets also affect the Red Sea in other ways?

Blasts of dry air

We decided to put together lots of different data to find out the fundamental characteristics of these mountain-gap jet events. Our data came from satellites and from a heavily instrumented mooring that measured winds and humidity in the air and temperatures and salinity in the sea below. WHOI maintained the mooring for two-years in the Red Sea when it collaborated with King Abdullah University of Science and Technology.

The satellite images revealed that these events weren’t rare. We learned that in most winters, there are typically two to three events in December and January in which the winds blow west across the northern part of the Red Sea. In satellite images, they are impressive and beautiful.

The mountain-gap events typically last three to eight days. We observed large year-to-year differences, with an increasing number of events in the last decade.

­We discovered that the wintertime mountain-gap wind events blast the Red Sea with dry air. They are like the cold-air outbreaks that hit the U.S. East Coast in winter. Of course, for the Red Sea, it would be better to name them as dry-air outbreaks!

The dry-air blasts abruptly increase evaporation on the surface of the sea. This colossal evaporation removes a large amount of heat and water vapor out of the sea, leaving it much saltier. The mountain-gap winds also stir up deeper, cooler waters that mix with surface waters.

The waters become saltier and colder. This disrupts the Eastern Boundary Current. During most wind-jet events, it seems to fade away.

Connecting the oceans

We are still looking for answers about how the Eastern Boundary Current forms and why it flows north. But we have learned much about the wind-jet events that cause it to disappear periodically in winter.

The large-scale evaporation from these wind-jet events may also drive waters in the northern Red Sea to become cooler, saltier, and dense enough to sink the depths and flow all the way south and back out of the Strait of Bab Al Mandeb.

These salty Red Sea waters escape to the Gulf Aden, where they start a long journey through the Indian Ocean. They cross the Equator. Some may travel into the Atlantic Ocean. Some may flow toward Western Australia.

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#10739. What does the term in Biology Food chain mean?

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#2564. What does the medical term Dix–Hallpike test mean?