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Peneplain
390px, Sketch of a hypothetical peneplain formation after an orogeny. In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or penultimate) stage of fluvial erosion during times of extended tectonic stability. Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis, but Davis and other workers have also used the term in a purely descriptive manner without any theory or particular genesis attached. The existence of some peneplains, and peneplanation as a process in nature, is not without controversy, due to a lack of contemporary examples and uncertainty in identifying relic examples. By some definitions, peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored. Geomorphologist Karna Lidmar-Bergstrà ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peneplain
390px, Sketch of a hypothetical peneplain formation after an orogeny. In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage of peneplain is meant to imply the representation of a near-final (or penultimate) stage of fluvial erosion during times of extended tectonic stability. Peneplains are sometimes associated with the cycle of erosion theory of William Morris Davis, but Davis and other workers have also used the term in a purely descriptive manner without any theory or particular genesis attached. The existence of some peneplains, and peneplanation as a process in nature, is not without controversy, due to a lack of contemporary examples and uncertainty in identifying relic examples. By some definitions, peneplains grade down to a base level represented by sea level, yet in other definitions such a condition is ignored. Geomorphologist Karna Lidmar-Bergstrà ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pediplain
In geology and geomorphology a pediplain (from the Latin ''pes'', genitive case ''pedis'', meaning "foot") is an extensive plain formed by the coalescence of pediments. The processes through which pediplains forms is known as pediplanation. The concepts of pediplain and pediplanation were first developed by geologist Lester Charles King in his 1942 book ''South African Scenery''. The concept gained notoriety as it was juxtaposed to peneplanation. The coalesced pediments of the pediplains may form a series of very gentle concave slopes. Pediplains main difference to W. M. Davis’ peneplains is in the history and processes behind, and less so in the final shape. Perhaps the most notable difference in form that may be present is that of residual hills which in Davis’ peneplains are to have gentle slopes while in pediplains they ought to have the same steepness as the slopes in the early stages of erosion leading to pediplanation. Pediplanation is linked to scarp retreat in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pediplain
In geology and geomorphology a pediplain (from the Latin ''pes'', genitive case ''pedis'', meaning "foot") is an extensive plain formed by the coalescence of pediments. The processes through which pediplains forms is known as pediplanation. The concepts of pediplain and pediplanation were first developed by geologist Lester Charles King in his 1942 book ''South African Scenery''. The concept gained notoriety as it was juxtaposed to peneplanation. The coalesced pediments of the pediplains may form a series of very gentle concave slopes. Pediplains main difference to W. M. Davis’ peneplains is in the history and processes behind, and less so in the final shape. Perhaps the most notable difference in form that may be present is that of residual hills which in Davis’ peneplains are to have gentle slopes while in pediplains they ought to have the same steepness as the slopes in the early stages of erosion leading to pediplanation. Pediplanation is linked to scarp retreat in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycle Of Erosion
The geographic cycle, or cycle of erosion, is an idealized model that explains the development of relief in landscapes. The model starts with the erosion that follows uplift of land above a base level and ends, if conditions allow, in the formation of a peneplain. Landscapes that show evidence of more than one cycle of erosion are termed "polycyclical". The cycle of erosion and some of its associated concepts have, despite their popularity, been a subject of much criticism. Description William Morris Davis, the originator of the model, divided it into stages whose transition is gradual. The model begins with an uplifted or to-be-uplifted landscape. Then Davis defined a ''youthful'' stage where river incision is the dominant process shaping the landscape. During the ''youthful'' stage height, differences between uplands and valley bottoms increase rapidly. The ''youthful'' stage is followed by a ''mature'' stage in which height differences between valley bottoms and uplands are at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etchplain
An etchplain is a plain where the bedrock has been subject to considerable "etching" or subsurface weathering. Etchplanation is the process forming etchplains. Contrary to what the name might suggest, etchplains are seldom completely flat and usually display some relief, as weathering of the bedrock does not advance uniformly. This means that weathering is unrelated to the flatness which might be derivative of various other processes of planation including peneplanation and pediplanation. Erosion of etchplains can result in the exposure of inselbergs such as bornhardt and tors. Generally the topography exposed at a stripped etchplain, that is an etch surface, after erosion of regolith is one with many irregularities as result of structurally defined areas of rock strength. A distinction can be made between etchplains and etch surfaces as the latter may or may not be flat and can represent the landform arising from the stripping of an etchplain. As climate changes, arid and s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sub-Mesozoic Hilly Peneplains
200px, An undulating hilly landscape in Halland.html"_;"title="Falkenberg_Municipality,_Halland">Falkenberg_Municipality,_Halland. file:Dagsås_-_KMB_-_16000700002822.jpg.html" ;"title="Halland..html" ;"title="Halland.html" ;"title="Falkenberg Municipality, Falkenberg_Municipality,_Halland.">Halland.html"_;"title="Falkenberg_Municipality,_Halland">Falkenberg_Municipality,_Halland. file:Dagsås_-_KMB_-_16000700002822.jpg">thumb.html" ;"title="Halland">Falkenberg Municipality, Halland.html"_;"title="Falkenberg_Municipality,_Halland">Falkenberg_Municipality,_Halland. file:Dagsås_-_KMB_-_16000700002822.jpg">thumb">200px.html" ;"title="Halland.">Halland.html" ;"title="Falkenberg Municipality, Halland">Falkenberg Municipality, Halland. file:Dagsås_-_KMB_-_16000700002822.jpg">thumb">200px">An undulating hilly landscape in Varberg Municipality, Halland. The Sub-Mesozoic hilly peneplains or Sub-Mesozoic hilly relief is a landscape in Scandinavia made up of undulating hills and joint va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plain
In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands. In a valley, a plain is enclosed on two sides, but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains, or by cliffs. Where a geological region contains more than one plain, they may be connected by a pass (sometimes termed a gap). Coastal plains mostly rise from sea level until they run into elevated features such as mountains or plateaus. Plains are one of the major landforms on earth, where they are present on all continents, and cover more than one-third of the world's land area. Plains can be formed from flowing lava; from deposition of sediment by water, ice, or wind; or formed by erosion by the agents from hills and mountains. Biomes on plains include grassland ( temperate or subtr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Base Level
In geology and geomorphology a base level is the lower limit for an erosion process. The modern term was introduced by John Wesley Powell in 1875. The term was subsequently appropriated by William Morris Davis who used it in his cycle of erosion theory. The "ultimate base level" is the plane that results from projection of the sea level under landmasses. It is to this base level that topography tends to approach due to erosion, eventually forming a peneplain close to the end of a cycle of erosion.Phillips, Jonathan D. (2002)"Erosion, isostatic response, and the missing peneplains" ''Geomorphology'', Vol. 45, No. 3-4Elsevier, 15 June 2002, pp. 225-241. . There are also lesser structural base levels where erosion is delayed by resistant rocks. Examples of this include karst regions underlain by insoluble rock. Base levels may be local when large landmasses are far from the sea or disconnected from it, as in the case of endorheic basins. An example of this is the Messinian salinity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyrenees
The Pyrenees (; es, Pirineos ; french: Pyrénées ; ca, Pirineu ; eu, Pirinioak ; oc, Pirenèus ; an, Pirineus) is a mountain range straddling the border of France and Spain. It extends nearly from its union with the Cantabrian Mountains to Cap de Creus on the Mediterranean Sea, Mediterranean coast. It reaches a maximum altitude of at the peak of Aneto. For the most part, the main crest forms a divide between Spain and France, with the microstate of Andorra sandwiched in between. Historically, the Crown of Aragon and the Kingdom of Navarre extended on both sides of the mountain range. Etymology In Greek mythology, Pyrene (mythology), Pyrene is a princess who eponym, gave her name to the Pyrenees. The Greek historiography, Greek historian Herodotus says Pyrene is the name of a town in Celts, Celtic Europe. According to Silius Italicus, she was the virgin daughter of Bebryx, a king in Narbonensis, Mediterranean Gaul by whom the hero Hercules was given hospitality during his ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodes Fairbridge
Rhodes Whitmore Fairbridge (21 May 1914 – 8 November 2006) was an Australian geologist and expert on climate change. His father was Kingsley Fairbridge. Born in Pinjarra, Western Australia, Fairbridge graduated from Queen's University in Ontario and earned his master's degree from Oxford. In 1941, he earned a doctorate in geology from the University of Western Australia. He taught at Columbia University from 1955 until his 1982 retirement. While there, he was supervising editor for the '' Encyclopedia of Earth Sciences''. In the early 1960s, he developed the so-called "Fairbridge Curve",15 October 2003 Classification of Coasts. ''Journal of Coastal Research'' pp. 155–165 a record of changes in sea levels over the last 10,000 years. In the 1980s Fairbridge wrote about climate's impact on the long-term evolution of shields and peneplains. Fairbridge died in 2006 in Amagansett, New York of a brain tumor.Pearce, Jeremy ( 27 November 2006). Rhodes W. Fairbridge, 92, Early Exper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tibetan Plateau
The Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the Tibet Autonomous Region, most of Qinghai, western half of Sichuan, Southern Gansu provinces in Western China, southern Xinjiang, Bhutan, the Indian regions of Ladakh and Lahaul and Spiti (Himachal Pradesh) as well as Gilgit-Baltistan in Pakistan, northwestern Nepal, eastern Tajikistan and southern Kyrgyzstan. It stretches approximately north to south and east to west. It is the world's highest and largest plateau above sea level, with an area of (about five times the size of Metropolitan France). With an average elevation exceeding and being surrounded by imposing mountain ranges that harbor the world's two highest summits, Mount Everest and K2, the Tibetan Plateau is often referred to as "the Roof of the World". The Tibetan Plateau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical erosion procee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
