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geomorphology
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The study of present-day landforms, including their classification, description, nature, origin development, and relationships to underlying structure. Also the history of geologic changes as recorded by these surface features. The term is sometimes restricted to features produced only by erosion and deposition.
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geomorphic cycle
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An idealized model of erosion wherein a plain is uplifted epeirogenically, then dissected by rapid streams (youth), then rounded by downslope movements into a landscape of steep hill (maturity), and finally reduced to a new peneplain at sea level (old age).
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morphology
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The study of shape or form.
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exogenic cycle
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Portion of the earth's system involved in the movement and mass transfer of substances through the cycle of weathering, erosion, transportation, deposition, burial, diagenesis and uplift. Reservoirs in the cycle generally include the atmosphere, ocean biota, sediment and shallow crust.
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peneplain
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A hypothetical extensive area of low elevation and relief reduced to near sea level by a long period of erosion and representing the end product of the ideal geomorphic cycle.
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old age
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A stage in the geomorphic cycle, characterized by formation of a peneplain near sea level.
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playa
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Playas are shallow, short-lived lakes that form where water drains into basin with no outlet to the sea and quickly evaporates. Playas are common features in arid (desert) regions and are among the flattest landforms in the world.
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lowland
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Land of general low relief at the lower levels of regional elevation.
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relief
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"A term used loosely for the physical shape, configuration, or general unevenness of a part of the Earth's surface, considered with reference to variations of height and slope or to irregularities of the land surface; the elevation or differences in elevation, considered collectively, of a land surface"
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hypsometric diagram
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A graph that shows in any way the relative amounts of the Earth's surface at different elevation with regard to sea level.
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elevation
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The vertical height of one point on the Earth above a given datum plane, usually sea level.
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plateau
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A flat or nearly flat area of high ground with steep sides standing above the surrounding country.
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tableland
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A large elevated region with a relatively low relief surface.
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topography
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"The shape of the Earth's surface, above and below sea level; the set of landforms in a region; the distribution of elevation. "
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cuesta
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A long, narrow hill with a steep slope on one side ant a gentle slope on the other.
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hogback
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A formation similar to a Cuesta in that it is a ridge formed by slower erosion of hard strata, but having two steep, equally inclined slope.
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escarpment
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A more or less continous cliff or relatively steep slope seperating two level or gently sloping surfaces produced by erosion or faulting.
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pediment
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A planar, sloping rock urface forming a ramp up to the front of a mountain range in an arid region. It may be covered locally by thin alluvium.
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monadnock
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An isolated hill or mountain rising above a peneplain.
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mesa
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An area of high flat land, a tableland, with steep sides. It has horizontal bed of hard bock, which resist erosion, on top.
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butte
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A steep sided and flat topped hill formed by erosion of flat laying strata where remnants of a resistant layer protect the softer rocks underneath.
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karst topography
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A distinctive landscape (topography) that can develop where the underlying bedrock, often limestone or marble, is partially dissoved by surface or ground water.
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orogeny
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The tectonic process in which large areas are folded, thrust-faulted, metamorphosed, and subjected to plutonism. The cycle ends with uplift and the formation of mountain.
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orogenic belt
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A linear region, often a former geo-syncline, that has been subjected to folding, and other deformation in a mountain-building episode.
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orogenic belt
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Linear region of the crust, where the lithosphere is relatively mobile and deformed into high-standing mountain belts. Most commonly forms in association with subduction zone or continental collision.
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geosyncline
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A major downwarp in the Earth's crust, usually more than 1000 kilometers in length, in which sediment accumulate to thicknesses of many kilometers. The sediments may eventually be deformed and metamorphosed during a mountain-building episode.
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miogeosyncline
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A geosyncline that is situated near a craton and receives chemical and well-sorted elastic sediment from the continent.
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eugeosyncline
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" The seaward part of a geosyncline; characterized by clastic sediment and volcanism. "
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shield
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Tectonically stable, low-lying Precambrian nucleus of continent. Commonly contains the metamorphosed roots of ancient orogenic activity.
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shields
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An extensive area of a continental plate where the igneous and metamorphic are exposed and have approached equilibrium in respect to erosion and isostasy. The rocks of a shield are usually Precambrian.
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continental shield
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A surface of low relief, within a few hundred meters above sea level, who's only features of relief are due to resistant rocks rising 50 to 100 m above their surroundings.
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shield
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"A large area of exposed basement rocks in a craton, commonly with a very gently convex surface, surrounded by sediment-covered platforms; e.g., Canadian Shield, Baltic Shield. The rocks of virtually all shield areas are Precambrian."
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craton
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The relatively stable nucleus of a continent. Cratons are made up of a shield-like core of Precambrian Rock and a buried extension of the shield
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craton
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A part of the Earth's crust that has attained stability, and has been little deformed for a prolonged period. The term is now restricted to the extensive central areas of the continent
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massif
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An isolated block within a group of mountain. It indicates that a mountain is a segment of crystalline basement, or a pluton which survived the erosional processes that wore down the rock that originally surrounded it.
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extension
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In geology, the process of stretching the Earth’s crust. Usually cracks (faults) form, and some blocks sink, forming sedimentary basin.
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stable platform
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Large areas of craton that have not been significantly uplifted above or submerged below sea level. Sedimentary rocks are nearly horizontal.
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horst
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An elongate block of rock uplifted along roughly parallel fault.
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graben
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An elongate block of rock down-dropped along roughly parallel fault.
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intermontane basin
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A basin between mountain ranges, often formed over a graben.
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rift structure
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"A long, narrow structural trough that is bounded by normal fault; a graben of regional extent"
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rift zone
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A region of Earth’s crust along which divergence is taking place. A linear zone of volcanic activity and faulting usually associated with diverging plate or crustal stretching.
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rift system
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"The oceanic ridge formed where tectonic plate are separating and a new crust is being created; also, their land counterparts, such as the East African Rift. "
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rift valley
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A fault trough formed in a divergence zone or other area of tension.
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strike valley
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A valley eroded parallel to the strike of the underlying strata.
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topographic map
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"See Contour map; also a schematic drawing of prominent landforms indicated by conventionalized symbols, such as hachures or contours. "
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extension
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In geology, the process of stretching the Earth’s crust. Usually cracks (faults) form, and some blocks sink, forming sedimentary basin.
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