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Physical Geography Of Assam
This article discusses the geological origin, geomorphic characteristics, and climate of the northeastern Indian state of Assam. Extending from 89° 42′ E to 96° E longitude and 24° 8′ N to 28° 2′ N latitude, it has an area of 78,438 km2, similar to that of Ireland or Austria. Geology Geologically, as per the plate tectonics, Assam is in the easternmost projection of the Indian Plate, where it thrusts underneath the Eurasian Plate creating a subduction zone. It is postulated that due to the northeasterly movement of the Indian plate, the sedimentary layers of an ancient geosyncline called the Tethys (in between Indian and Eurasian Plates) were pushed upward to form the Himalayas. It is estimated that the height of the Himalayas is increasing by 4 cm each year. Therefore, Assam possesses a special geomorphic environment, with large plains and dissected hills of the South Indian Plateau system abutting the Himalayas to the north, north-east and east. Geomorp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Assam Valley
The Brahmaputra Valley is a region situated between hill ranges of the eastern and northeastern Himalayan range in Eastern India. The valley consists of the Western Brahmaputra Valley covering the regions of Goalpara and Kamrup; the Central Brahmaputra Valley region covering Darrang, Nagaon and the North Bank and Eastern Brahmaputra Valley comprising districts of Sonitpur, Lakhimpur, Dibrugarh and Sibsagar. The Teesta River in North Bengal also drains into Brahmaputra River. The Brahmaputra Valley has a total area of 71,516 km² with containing 30 districts. Brahmaputra Valley with its rainforest-like climate contains some of the most productive soils in the world. The Brahmaputra River flows from Assam to Bangladesh where it meets the Ganges River to form the world's largest delta and finally flows into the Bay of Bengal in the south. Demography The majority of the people of the valley are Hindus, mostly speaking the Assamese language. The valley is more populou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Entrenched River
An entrenched river, or entrenched stream is a river or stream that flows in a narrow trench or valley cut into a plain or relatively level upland. Because of lateral erosion streams flowing over gentle slopes over a time develops meandering (snake like pattern) course. Meanders form where gradient is very gentle, for example in floodplain and delta. Meandering is the feature of the middle and final course of the river. But very deep and wide meanders can also be found cutting hard rocks. Such meanders are called incised or entrenched meanders. The exception is that entrenched meanders are formed during the upliftment of land where river is young. They widen and deepen over time and can be found as deep gorges or canyons in hard rock.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2005. ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. Licker, M.D., 2003. ''McGraw-Hill Dictionary of Environmental Science.'' McGraw-Hill Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sillimanite
Sillimanite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut. Occurrence Sillimanite is one of three aluminosilicate polymorphs, the other two being andalusite and kyanite. A common variety of sillimanite is known as ''fibrolite'', so named because the mineral appears like a bunch of fibres twisted together when viewed in thin section or even by the naked eye. Both the fibrous and traditional forms of sillimanite are common in metamorphosed sedimentary rocks. It is an index mineral indicating high temperature but variable pressure. Example rocks include gneiss and granulite. It occurs with andalusite, kyanite, potassium feldspar, almandine, cordierite, biotite and quartz in schist, gneiss, hornfels and also rarely in pegmatites. Dumortierite and mullite are similar mineral species found in porcelain.Klein, C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaolin
Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral sheet of alumina () octahedra. Rocks that are rich in kaolinite are known as kaolin () or china clay. Kaolin is occasionally referred to by the antiquated term lithomarge, from the Ancient Greek ''litho-'' and Latin ''marga'', meaning 'stone of marl'. Presently the name lithomarge can refer to a compacted, massive form of kaolin. The name ''kaolin'' is derived from Gaoling (), a Chinese village near Jingdezhen in southeastern China's Jiangxi Province. The name entered English in 1727 from the French version of the word: , following François Xavier d'Entrecolles's reports on the making of Jingdezhen porcelain. Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g). It is a soft, earthy, usu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quartzite
Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of hematite. Other colors, such as yellow, green, blue and orange, are due to other minerals. The term ''quartzite'' is also sometimes used for very hard but unmetamorphosed sandstones that are composed of quartz grains thoroughly cemented with additional quartz. Such sedimentary rock has come to be described as orthoquartzite to distinguish it from metamorphic quartzite, which is sometimes called metaquartzite to emphasize its metamorphic origins. Quartzite is very resistant to chemical weathering and often forms ridges and resistant hilltops. The nearly pure silica conte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. Vast deposits of coal originate in former wetlands called coal forests that covered much of the Earth's tropical land areas during the late Carboniferous ( Pennsylvanian) and Permian times. Many significant coal deposits are younger than this and originate from the Mesozoic and Cenozoic eras. Coal is used primarily as a fuel. While coal has been known and used for thousands of years, its usage was limited until the Industrial Revolution. With the invention of the steam engine, coal consumption increased. In 2020, coal supplied about a quarter of the world's primary energy and over a third of its electricity. Some iron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Natural gas is colorless and odorless, so odorizers such as mercaptan (which smells like sulfur or rotten eggs) are commonly added to natural gas supplies for safety so that leaks can be readily detected. Natural gas is a fossil fuel and non-renewable resource that is formed when layers of organic matter (primarily marine microorganisms) decompose under anaerobic conditions and are subjected to intense heat and pressure underground over millions of years. The energy that the decayed organisms originally obtained from the sun via photosynthesis is stored as chemical energy within the molecules of methane and other hydrocarbons. Natural gas can be burned fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude oil and petroleum products that consist of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, mostly zooplankton and algae, are buried underneath sedimentary rock and subjected to both prolonged heat and pressure. Petroleum is primarily recovered by oil drilling. Drilling is carried out after studies of structural geology, sedimentary basin analysis, and reservoir characterisation. Recent developments in technologies have also led to exploitation of other unconventional reserves such as oil sands and oil shale. Once extracted, oil is refined and separated, most easily by distillation, into innumerable products for direct use or use in manufacturing. Products include fuels such as gasol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barak Valley
The Barak Valley is located in the southern region of the Indian state of Assam. The region is named after the Barak river. The Barak valley consists of three administrative districts of Assam - namely Cachar, Karimganj, and Hailakandi. The main, largest and capital city of the Valley is Silchar. Once North Cachar Hills was a part of the valley but In 1951 erstwhile Sub-Division was made a separate district and eventually curved out of Cachar. On 1 July 1983, Karimganj district was curved out from the eponymous subdivision of Cachar Valley. This was again repeated in 1989 with the creation of Hailakandi district. Etymology The name "Barak" has derived from the Dimasa words 'Bra' & 'Kro'. Bra means bifurcation and Kro upper means portion/stream. The river Barak is bifurcated near Haritikar in the Karimganj district in to Surma River and Kushiyara River respectively. The upstream of this bifurcated river was called Brakro by the local Dimasa people. Barak valley excludin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dima Hasao District
Dima Hasao district (), earlier called North Cachar Hills district, is an administrative district in the state of Assam, India. As of 2011, it is the least populous district of Assam. Dima Hasao district is one of the two autonomous hill districts of the state of Assam. The district headquarters Haflong is the only hill station in Assam, a tourist destination, also nicknamed the Switzerland of the north-east. Etymology "Dima Hasao" means "Dimasa Hills" in the Dimasa language. History The earliest inhabitants of the present district were Mongoloid groups who preferred hilly terrain and practised their own culture, tradition and land rights, governing themselves as independent tribes. As per records of different British historians and officials, North Cachar Hills was already occupied by the Dimasa Kacharis, erstwhile old Kuki tribes viz. Biate, Hrangkhol, Hmar, Sakachep and Zeme Naga tribes, during the British Rule in India. Medieval period During the medieval period (1500–1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karbi Anglong
Karbi may refer to: Places * Karbi, Armenia * Karbi Anglong Plateau, an extension of the Indian Plate in Assam, India * Karbi Anglong district, a district of Assam, north-eastern India Other uses * Karbi people, an ethnic group of North-east India * Karbi language, the Sino-Tibetan languages spoken by Karbi people * Karbi languages, a branch of the Kuki-Chin group of Sino-Tibetan See also *Karli (name) *Karri (other) Karri may refer to the following: Places * Karri, Iran, a village in Iran *Karri forest, a forest type found in Australia Species * Pterostylis karri, species of orchid * Eucalyptus diversicolor, commonly known as the karri, is a eucalypt People ... {{disambiguation, geo Language and nationality disambiguation pages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
