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An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations.
An inselberg or monadnock is an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. In Southern Africa a similar formation of granite is known as a koppie, an Afrikaans word from the Dutch diminutive word kopje. If the inselberg is dome-shaped and formed from granite or gneiss, it can also be called a bornhardt, though not all bornhardts are inselbergs. An inselberg results when a body of rock resistant to erosion, such as granite, occurring within a body of softer rocks, is exposed by differential erosion and lowering of the surrounding landscape.
Regolith is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestrial planets and moons.
Landforms are categorized by characteristic physical attributes such as their creating process, shape, elevation, slope, orientation, rock exposure, and soil type.
In geomorphology, a butte is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word butte comes from the French word butte, meaning knoll ; its use is prevalent in the Western United States, including the southwest where mesa is used for the larger landform. Due to their distinctive shapes, buttes are frequently landmarks in plains and mountainous areas. To differentiate the two landforms, geographers use the rule of thumb that a mesa has a top that is wider than its height, while a butte has a top that is narrower than its height.
A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a more resistant layer or layers of harder rock, e.g. shales overlain by sandstones. The resistant layer acts as a caprock that forms the flat summit of a mesa. The caprock can consist of either sedimentary rocks such as sandstone and limestone; dissected lava flows; or a deeply eroded duricrust. Unlike plateau, whose usage does not imply horizontal layers of bedrock, e.g. Tibetan Plateau, the term mesa applies exclusively to the landforms built of flat-lying strata. Instead, flat-topped plateaus are specifically known as tablelands.
In geology and physical geography, a plateau, also called a high plain or a tableland, is an area of a highland consisting of flat terrain that is raised sharply above the surrounding area on at least one side. Often one or more sides have deep hills or escarpments. Plateaus can be formed by a number of processes, including upwelling of volcanic magma, extrusion of lava, and erosion by water and glaciers. Plateaus are classified according to their surrounding environment as intermontane, piedmont, or continental. A few plateaus may have a small flat top while others have wider ones.
The Colorado Plateau is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This plateau covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.
A cuesta is a hill or ridge with a gentle slope on one side, and a steep slope on the other. In geology, the term is more specifically applied to a ridge where a harder sedimentary rock overlies a softer layer, the whole being tilted somewhat from the horizontal. This results in a long and gentle backslope called a dip slope that conforms with the dip of resistant strata, called caprock. Where erosion has exposed the frontslope of this, a steep slope or escarpment occurs. The resulting terrain may be called scarpland.
A dip slope is a topographic (geomorphic) surface which slopes in the same direction, and often by the same amount, as the true dip or apparent dip of the underlying strata. A dip slope consists of the upper surface of a resistant layer of rock, often called caprock, that is commonly only slightly lowered and reduced in steepness by erosion. Dip slopes form the backslopes of cuestas, homoclinal ridges, hogbacks, and flatirons. The frontslopes of such ridges consist of either an escarpment, a steep slope, or perhaps even a line of cliffs. Generally, cuestas and homoclinal ridges are asymmetrical in that their dip slopes are less steep than their escarpments. In the case of hogbacks and flatirons, the dip of the rocks is so steep that their dip slope approaches the escarpment in their steepness.
Ultramafic rocks are igneous and meta-igneous rocks with a very low silica content, generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals. The Earth's mantle is composed of ultramafic rocks. Ultrabasic is a more inclusive term that includes igneous rocks with low silica content that may not be extremely enriched in Fe and Mg, such as carbonatites and ultrapotassic igneous rocks.
Boulder clay is an unsorted agglomeration of clastic sediment that is unstratified and structureless and contains gravel of various sizes, shapes, and compositions distributed at random in a fine-grained matrix. The fine-grained matrix consists of stiff, hard, pulverized clay or rock flour. Boulder clay is also known as drift clay; till; unstratified drift, Geschiebelehm (German); argile á blocaux (French); and keileem (Dutch).
This glossary of geology is a list of definitions of terms and concepts relevant to geology, its sub-disciplines, and related fields. For other terms related to the Earth sciences, see Glossary of geography terms.
Inverted relief, inverted topography, or topographic inversion refers to landscape features that have reversed their elevation relative to other features. It most often occurs when low areas of a landscape become filled with lava or sediment that hardens into material that is more resistant to erosion than the material that surrounds it. Differential erosion then removes the less resistant surrounding material, leaving behind the younger resistant material, which may then appear as a ridge where previously there was a valley. Terms such as "inverted valley" or "inverted channel" are used to describe such features. Inverted relief has been observed on the surfaces of other planets as well as on Earth. For example, well-documented inverted topographies have been discovered on Mars.
Saprolite is a chemically weathered rock. Saprolites form in the lower zones of soil profiles and represent deep weathering of the bedrock surface. In most outcrops, its color comes from ferric compounds. Deeply weathered profiles are widespread on the continental landmasses between latitudes 35°N and 35°S.
Scarp retreat is a geological process through which the location of an escarpment changes over time. Typically the cliff is undermined, rocks fall and form a talus slope, the talus is chemically or mechanically weathered and then removed through water or wind erosion, and the process of undermining resumes. Scarps may retreat for tens of kilometers in this way over relatively short geological time spans, even in arid locations.
The Bass Formation, also known as the Bass Limestone, is a Mesoproterozoic rock formation that outcrops in the eastern Grand Canyon, Coconino County, Arizona. The Bass Formation erodes as either cliffs or stair-stepped cliffs. In the case of the stair-stepped topography, resistant dolomite layers form risers and argillite layers form steep treads. In general, the Bass Formation in the Grand Canyon region and associated strata of the Unkar Group-rocks dip northeast (10°–30°) toward normal faults that dip 60+° toward the southwest. This can be seen at the Palisades fault in the eastern part of the main Unkar Group outcrop area. In addition, thick, prominent, and dark-colored basaltic sills intrude across the Bass Formation.
The Shinarump Conglomerate is a geologic formation found in the Four Corners region of the United States. It was deposited in the early part of the Late Triassic period.
The Serra dos Órgãos is a mountain range in the state of Rio de Janeiro, Brazil. It contains the Serra dos Órgãos National Park.
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.
References
- ↑ Neuendorf, K.K.E.; Mehl, Jr., J.P.; Jackson, J.A., eds. (2005). Glossary of Geology (5th ed.). Alexandria, VA: American Geological Institute. ISBN 0-922152-76-4. OCLC 894898557.
- 1 2 Duszyński, F.; Migoń, P.; Strzelecki, M.C. (September 2019). "Escarpment retreat in sedimentary tablelands and cuesta landscapes–Landforms, mechanisms and patterns". Earth-Science Reviews. 169: 102890. doi:10.1016/j.earscirev.2019.102890.
- 1 2 Migoń, P.; Duszyński, F. (November 2022). "Landscapes and landforms in coarse clastic sedimentary tablelands–Is there a unifying theme?". Catena. 218: 106545. doi: 10.1016/j.catena.2022.106545 .
- ↑ Migoń, P.; Duszyński, F.; Jancewicz, K. and; Kotwicka, W. (October 2020). "Late evolutionary stages of residual hills in tablelands (Elbsandsteingebirge, Germany)". Geomorphology. 367: 107308. doi: 10.1016/j.geomorph.2020.107308 .
- ↑ Kumar, V.S. (2015). "The laterite-capped Panchgani Tableland, Deccan Traps". In Kale, V. (ed.). Landscapes and Landforms of India. World Geomorphological Landscapes. Springer. pp. 217–222. doi:10.1007/978-94-017-8029-2_23. ISBN 978-94-017-8029-2.
- ↑ Rabassa, J.; Carignano, C.; Cioccale, M. (2010). "Gondwana paleosurfaces in Argentina: an introduction". Geociências. 29 (4): 430–466.
- ↑ Anand, R.R.; de Broekert, P. (2005). "Weathering history, landscape evolution and implications for exploration". In Anand, R.R.; de Broekert, P. (eds.). Regolith Landscape Evolution Across Australia: A Compilation of Regolith Landscape Case Studies With Regolith Landscape Evolution Models. Perth, West Australia: CRC LEME. pp. 2–40. ISBN 1-921039-30-2. OCLC 225089086.
- ↑ Ferrill, D.A.; Morris, A.P.; McGinnis, R.N.; Smart, K.J.; Watson-Morris, M.J.; Wigginton, S.S. (2016). "Observations on normal-fault scarp morphology and fault system evolution of the Bishop Tuff in the Volcanic Tableland, Owens Valley, California, USA". Lithosphere. 8 (3): 238–253. doi: 10.1130/L476.1 .
