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22-668: The Khasi Hills ( / ˈ k ɑː s i / ) are a low mountain formation on the Shillong Plateau in the Meghalaya state of India . The Khasi Hills are part of the Garo-Khasi-Jaintia range and connect with the Purvanchal Range and the larger Patkai Range further east. The Khasi Hills, and the whole Garo-Khasi-Jaintia range, are in the Meghalaya subtropical forests ecoregion. The Khasi Hills, and

44-480: A ramp and typically forms at an angle of about 15°–30° to the bedding. Continued displacement on a thrust over a ramp produces a characteristic fold geometry known as a ramp anticline or, more generally, as a fault-bend fold . Fault-propagation folds form at the tip of a thrust fault where propagation along the decollement has ceased, but displacement on the thrust behind the fault tip continues. The formation of an asymmetric anticline-syncline fold pair accommodates

66-402: A sedimentary sequence, such as mudstones or halite layers; these parts of the thrust are called decollements . If the effectiveness of the decollement becomes reduced, the thrust will tend to cut up the section to a higher stratigraphic level until it reaches another effective decollement where it can continue as bedding parallel flat. The part of the thrust linking the two flats is known as

88-408: A sedimentary sequence, such as the top and base of a relatively strong sandstone layer bounded by two relatively weak mudstone layers. When a thrust that has propagated along the lower detachment, known as the floor thrust , cuts up to the upper detachment, known as the roof thrust , it forms a ramp within the stronger layer. With continued displacement on the thrust, higher stresses are developed in

110-399: Is a type of reverse fault that has a dip of 45 degrees or less. If the angle of the fault plane is lower (often less than 15 degrees from the horizontal ) and the displacement of the overlying block is large (often in the kilometer range) the fault is called an overthrust or overthrust fault . Erosion can remove part of the overlying block, creating a fenster (or window ) – when

132-416: Is typically a lozenge-shaped duplex. Most duplexes have only small displacements on the bounding faults between the horses, which dip away from the foreland. Occasionally, the displacement on the individual horses is more significant, such that each horse lies more or less vertically above the other; this is known as an antiformal stack or imbricate stack . If the individual displacements are still greater,

154-611: The Alps , and the Appalachians are prominent examples of compressional orogenies with numerous overthrust faults. Thrust faults occur in the foreland basin , marginal to orogenic belts. Here, compression does not result in appreciable mountain building, which is mostly accommodated by folding and stacking of thrusts. Instead, thrust faults generally cause a thickening of the stratigraphic section . When thrusts are developed in orogens formed in previously rifted margins, inversion of

176-693: The Garo , Khasi and Jaintia Hills , respectively. The plateau shows numerous fracture lineaments in satellite images and has been subjected to extensive and compressive forces in the N-S and E-W direction respectively. Several deep earthquakes point to tectonic activity in the mantle , such as from the 1897 Assam earthquake along the blind Oldham Fault . Linguistically, it is the homeland to Khasic languages . 25°34′55″N 91°59′56″E  /  25.582°N 91.999°E  / 25.582; 91.999 Thrust fault#Blind thrust faults A thrust fault

198-652: The Ri-Bhoi District was carved out of the East Khasi Hills District. The population of the region according to the 2011 Census is 1,468,223. Religion in Khasi Hills (2011) A vast majority of 1,128,769 people in Khasi Hills follow Christianity of various denominations, mostly Presbyterian and Catholic . Hinduism is mainly followed by 182,353 people, mainly non-tribals ( Bengalis , Nepalis , Biharis , Marwaris etc.) living in

220-412: The ocean trench margin of subduction zones, where oceanic sediments are scraped off the subducted plate and accumulate. Here, the accretionary wedge must thicken by up to 200%, and this is achieved by stacking thrust fault upon thrust fault in a melange of disrupted rock, often with chaotic folding. Here, ramp flat geometries are not usually observed because the compressional force is at a steep angle to

242-536: The Khasi Hills district, which was divided into the West Khasi Hills and East Khasi Hills districts on 28 October 1976. The highest peak is Lum Shyllong which is 1,968 metres (6,457 ft) high. It is situated a few kilometers south of Shillong town. Administratively, the Khasi Hills used to be a part of the Khasi Hills district. The district was divided into East Khasi Hills district and West Khasi Hills district on 28 October 1976. On 4 June 1992,

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264-514: The buried paleo-rifts can induce the nucleation of thrust ramps. Foreland basin thrusts also usually observe the ramp-flat geometry, with thrusts propagating within units at very low angle "flats" (at 1–5 degrees) and then moving up-section in steeper ramps (at 5–20 degrees) where they offset stratigraphic units. Thrusts have also been detected in cratonic settings, where "far-foreland" deformation has advanced into intracontinental areas. Thrusts and duplexes are also found in accretionary wedges in

286-446: The continuing displacement. As displacement continues, the thrust tip starts to propagate along the axis of the syncline. Such structures are also known as tip-line folds . Eventually, the propagating thrust tip may reach another effective decollement layer, and a composite fold structure will develop with fault-bending and fault-propagation folds' characteristics. Duplexes occur where two decollement levels are close to each other within

308-569: The entire Meghalaya state, was administratively part of Assam before 1970. In older sources in particular, the alternative transcription Khasia Hills is seen. The region is inhabited mainly by tribal Khasi dwellers, who are traditionally in various chieftainships, states known as the Khasi Hill States . One of its capitals, Sohra , is considered one of the wettest places in the world. The majority of Khasis are Presbyterians followed by Catholics and Anglicans. The region came under

330-429: The footwall of the ramp due to the bend on the fault. This may cause renewed propagation along the floor thrust until it again cuts up to join the roof thrust. Further displacement then takes place via the newly created ramp. This process may repeat many times, forming a series of fault-bounded thrust slices known as imbricates or horses , each with the geometry of a fault-bend fold of small displacement. The final result

352-505: The horses have a foreland dip. Duplexing is a very efficient mechanism of accommodating the shortening of the crust by thickening the section rather than by folding and deformation. Large overthrust faults occur in areas that have undergone great compressional forces. These conditions exist in the orogenic belts that result from either two continental tectonic collisions or from subduction zone accretion. The resultant compressional forces produce mountain ranges. The Himalayas ,

374-501: The multi-diverse East Khasi Hills district. 25°35′N 91°38′E  /  25.583°N 91.633°E  / 25.583; 91.633 This article related to a location in the Indian state of Meghalaya is a stub . You can help Misplaced Pages by expanding it . Shillong Plateau The Shillong Plateau is a plateau in the eastern Meghalaya state of India. The plateau's western, northern, and southern ridges form

396-531: The region. A small segment of Khasi tribe members numbering around 127,735 still follow their indigenous tribal religion called "Ka Niam Khasi", Islam is a tiny minority with around 17,471 people following it. 0.81 percent follow other religions. Languages of Khasi Hills (2011) Khasi is spoken by 1,149,178 people as their mother tongue, Garo is spoken by 88,533. While Bengali and Nepali come in at 3rd and 4th position, spoken by 56,086 and 48,010 people respectively. A vast number of non-tribals can be found in

418-890: The sedimentary layering. Thrust faults were unrecognised until the work of Arnold Escher von der Linth , Albert Heim and Marcel Alexandre Bertrand in the Alps working on the Glarus Thrust ; Charles Lapworth , Ben Peach and John Horne working on parts of the Moine Thrust in the Scottish Highlands ; Alfred Elis Törnebohm in the Scandinavian Caledonides and R. G. McConnell in the Canadian Rockies. The realisation that older strata could, via faulting, be found above younger strata

440-621: The underlying block is exposed only in a relatively small area. When erosion removes most of the overlying block, leaving island-like remnants resting on the lower block, the remnants are called klippen (singular klippe ). If the fault plane terminates before it reaches the Earth's surface, it is called a blind thrust fault. Because of the lack of surface evidence, blind thrust faults are difficult to detect until rupture. The destructive 1994 earthquake in Northridge, Los Angeles, California ,

462-439: Was arrived at more or less independently by geologists in all these areas during the 1880s. Geikie in 1884 coined the term thrust-plane to describe this special set of faults. He wrote: By a system of reversed faults, a group of strata is made to cover a great breadth of ground and actually to overlie higher members of the same series. The most extraordinary dislocations, however, are those to which for distinction we have given

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484-456: Was caused by a previously undiscovered blind thrust fault. Because of their low dip , thrusts are also difficult to appreciate in mapping, where lithological offsets are generally subtle and stratigraphic repetition is difficult to detect, especially in peneplain areas. Thrust faults, particularly those involved in thin-skinned style of deformation, have a so-called ramp-flat geometry. Thrusts mainly propagate along zones of weakness within

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