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An inselberg or monadnock () is an isolated rock hill, knob, ridge, or small
mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...
that rises abruptly from a gently sloping or virtually level surrounding
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
Southern Africa Southern Africa is the southernmost subregion of the African continent, south of the Congo and Tanzania. The physical location is the large part of Africa to the south of the extensive Congo River basin. Southern Africa is home to a number of ...
a similar formation of granite is known as a koppie, an
Afrikaans Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their enslaved people. Afrikaans gra ...
word ("little head") from the
Dutch Dutch commonly refers to: * Something of, from, or related to the Netherlands * Dutch people () * Dutch language () Dutch may also refer to: Places * Dutch, West Virginia, a community in the United States * Pennsylvania Dutch Country People E ...
diminutive word ''kopje''. If the inselberg is dome-shaped and formed from
granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
or
gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...
, it can also be called a
bornhardt A bornhardt () is a dome-shaped, steep-sided, bald rock outcropping at least in height and several hundred metres in width. They are named after Wilhelm Bornhardt (1864–1946), a German geologist and explorer of German East Africa, who first ...
, 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 Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
and lowering of the surrounding landscape.


Etymology


Inselberg

The word ''inselberg'' is a
loan word A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because the ...
from
German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...
, and means "island mountain". The term was coined in 1900 by geologist
Wilhelm Bornhardt Friedrich Wilhelm Conrad Eduard Bornhardt (20 April 1864 Braunschweig - 2 December 1946 Goslar) was a German geologist, engineer and explorer, and was Director of the Berlin College of Mines (Bergakademie) from 1907 to 1916. He explored and set out ...
(1864–1946) to describe the abundance of such features found in eastern
Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
. At that time, the term applied only to arid landscape features. However, it has since been used to describe a broader geography and range of rock features, leading to confusion about the precise definition of the term. In a 1973 study examining the use of the term, one researcher found that the term had been used for features in
savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the Canopy (forest), canopy does not close. The open canopy allows sufficient light to rea ...
climates 40% of the time, arid or semi-arid climates 32% of the time, humid-subtropical and arctic 12% of the time, and 6% each in humid-tropical and Mediterranean climates. A 1972 paper defined inselbergs as "steep-sided isolated hills rising relatively abruptly above gently sloping ground". This definition includes such features as
butte __NOTOC__ 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 a French word mea ...
s; conical hills with rectilinear sides typically found in arid regions;
regolith 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 terrestria ...
-covered concave-convex hills; rock crests over regolith slopes; rock domes with near vertical sides;
tors Tors may refer to: * Tor (rock formation), rock outcrops * Ivan Tors (1916–1983), playwright, screenwriter and film and television producer * TransOral Robotic Surgery, a surgical technique See also * Tor (disambiguation) * Ten Tors * Tors Cov ...
(koppies) formed of large boulders but with solid rock cores. Thus, the terms monadnock and inselberg may not perfectly match,Gerrard, John (1988).
Rocks and Landforms
' Routledge: Florence, Kentucky.
though some authors have explicitly argued these terms are completely synonymous.


Monadnock

''Monadnock'' is derived from a Native American term for an isolated
hill A hill is a landform that extends above the surrounding terrain. It often has a distinct Summit (topography), summit. Terminology The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally con ...
or a lone mountain that stands above the surrounding area, typically by surviving erosion. Geologists took the name from
Mount Monadnock Mount Monadnock, or Grand Monadnock, is a mountain in the towns of Jaffrey and Dublin, New Hampshire. It is the most prominent mountain peak in southern New Hampshire and is the highest point in Cheshire County. It lies southwest of Concord a ...
in southwestern
New Hampshire New Hampshire is a U.S. state, state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
.
Raymo, Chet Chet Raymo (born September 17, 1936 in Chattanooga, Tennessee) is a noted writer, educator and naturalist. He is Professor Emeritus of Physics at Stonehill College, in Easton, Massachusetts. His weekly newspaper column ''Science Musings'' appea ...
and
Raymo, Maureen E. Maureen E. "Mo" Raymo (born 1959) is an American paleoclimatologist and marine geologist. She is the Co-Founding Dean of the Columbia Climate School, Director of the Lamont–Doherty Earth Observatory of Columbia University, the G. Unger Vetl ...
(1989) ''Written in Stone: A Geologic History of the Northeastern United States.'' Globe Pequot, Chester, Connecticut.
It is thought to derive from the
Abenaki The Abenaki (Abenaki: ''Wαpánahki'') are an Indigenous peoples of the Northeastern Woodlands of Canada and the United States. They are an Algonquian-speaking people and part of the Wabanaki Confederacy. The Eastern Abenaki language was predom ...
language, from either ''menonadenak'' ("smooth mountain") or ''menadena'' ("isolated mountain"). In this context, ''monadnock'' is used to describe a mountain that rises from an area of relatively flat and/or lower terrain. For instance, Mount Monadnock rises above its surrounding terrain and stands, at , nearly higher than any mountain peak within .


Geology


Geological and geographical patterns

Inselbergs are common in eroded and weathered
shield A shield is a piece of personal armour held in the hand, which may or may not be strapped to the wrist or forearm. Shields are used to intercept specific attacks, whether from close-ranged weaponry or projectiles such as arrows, by means of a ...
s. The presence of an inselberg typically indicates the existence of a nearby
plateau 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 ha ...
or highland, or their remnants. This is especially the case for inselbergs composed of
sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
, which will display the same stratigraphic units as this nearby plateau. However once exposed, the inselbergs are destroyed by marginal collapse of joint blocks and exfoliation sheets. This process leaves behind
tors Tors may refer to: * Tor (rock formation), rock outcrops * Ivan Tors (1916–1983), playwright, screenwriter and film and television producer * TransOral Robotic Surgery, a surgical technique See also * Tor (disambiguation) * Ten Tors * Tors Cov ...
perched at their summits and, over time, a talus-bordered residual known as a ''castle koppie'' appears. By this association various inselberg fields in Africa and South America are assumed to be the vestiges of eroded
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 usu ...
s. Clusters of inselbergs, called inselberg fields and inselberg plains, occur in various parts of the world, including
Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...
, the
Anti-Atlas The Anti-Atlas ( ar, الأطلس الصغير, shi, Aṭlas Mẓẓiyn), also known as Lesser Atlas or Little Atlas is a mountain range in Morocco, a part of the Atlas Mountains in the northwest of Africa. The Anti-Atlas extends from the Atlanti ...
of
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
,
Northeast Brazil The Northeast Region of Brazil ( pt, Região Nordeste do Brasil; ) is one of the five official and political regions of the country according to the Brazilian Institute of Geography and Statistics. Of Brazil's twenty-six states, it comprises ni ...
,
Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...
, the interior of
Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...
, and the northern portions of
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...
and
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
. The classification of Anthony Young (1969) distinguishes six types of inselbergs;
butte __NOTOC__ 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 a French word mea ...
s,
conical hill A conical hill (also cone or conical mountain) is a landform with a distinctly conical shape. It is usually isolated or rises above other surrounding foothills, and is often of volcanic origin. Conical hills or mountains occur in different sha ...
s, convex-concave hills, rock crest over regolith-covered slope, rock dome (sugarloaf) and kopje or tor. The types of rock of which inselbergs are made of include
granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
,
gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...
and
gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is che ...
.


Origin and development

Summarizing the understanding on the origin of inselbergs in 1974, geomorphologist Michael Thomas writes "Hypotheses for the development of inselbergs have been advanced, refuted and reiterated over a period of more than seventy years."
Volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...
or other processes may give rise to a body of
rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...
resistant to
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 distin ...
, inside a body of softer rock such as
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 whe ...
, which is more susceptible to erosion. When the less resistant rock is eroded away to form a
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 ...
, the more resistant rock is left behind as an isolated mountain. The strength of the uneroded rock is often attributed to the tightness of its jointing. Inselbergs can be reshaped by
ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Las ...
s much the same way as
roches moutonnée Roche (F. Hoffmann–La Roche) is a Swiss healthcare company. Roche may also refer to: Companies *Roche Diagnostics, a division of F. Hoffmann–La Roche ** Roche Applied Science, a business group of Roche Diagnostics Places France *Roche, I ...
s. In northern Sweden, examples of this type of inselberg are called ''flyggbergs''.


Ecology

The inselbergs of Eastern Africa tend to be a refuge for life in the
Serengeti The Serengeti ( ) ecosystem is a geographical region in Africa, spanning northern Tanzania. The protected area within the region includes approximately of land, including the Serengeti National Park and several game reserves. The Serengeti ...
of
Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...
and
Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...
. Where the soil is too thin or hard to support tree life in large areas, soil trapped by inselbergs can be dense with trees while the surrounding land contains only short grass. Hollows in the rock surfaces provide catchments for rainwater.Serengeti National Park Visitor Center, Tanzania Many animals have adapted to the use of inselbergs, including the
lion The lion (''Panthera leo'') is a large Felidae, cat of the genus ''Panthera'' native to Africa and India. It has a muscular, broad-chested body; short, rounded head; round ears; and a hairy tuft at the end of its tail. It is sexually dimorphi ...
, the
hyrax Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simil ...
, and an abundance of bird and reptile life.


Gallery

File:Houtkop en R26-roete, Reitz-Daniëlsrus, Vrystaat.jpg, Houtkop, a outcrop of
Drakensberg The Drakensberg (Afrikaans: Drakensberge, Zulu: uKhahlambha, Sotho: Maluti) is the eastern portion of the Great Escarpment, which encloses the central Southern African plateau. The Great Escarpment reaches its greatest elevation – within th ...
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
in the Free State,
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
. File:Free State Koppie - panoramio.jpg, A conical sandstone koppie in the Free State, South Africa. File:Amazon jungle from above.jpg, An inselberg in the rainforest of
Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
. File:2008-06-28 08-18-02 Namibia Erongo Usakos.JPG, The
Spitzkoppe The Spitzkoppe (from German for ''"pointed dome"''; also referred to as Spitzkop, Groot Spitzkop, or the "Matterhorn of Namibia") is a group of bald granite peaks or inselbergs located between Usakos and Swakopmund in the Namib desert of Nam ...
of Namibia, a
granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
peak formed by early
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
rifting and magmatism. File:De Yalgo a Dori Marco Schmidt 0922.jpg, A
duricrust Duricrust is a hard layer on or near the surface of soil. Duricrusts can range in thickness from a few millimeters or centimeters to several meters. It is a general term (not to be confused with duripan) for a zone of chemical precipitation and ...
inselberg near Dori,
Burkina Faso Burkina Faso (, ; , ff, 𞤄𞤵𞤪𞤳𞤭𞤲𞤢 𞤊𞤢𞤧𞤮, italic=no) is a landlocked country in West Africa with an area of , bordered by Mali to the northwest, Niger to the northeast, Benin to the southeast, Togo and Ghana to the ...
. File:Petermann Ranges (AU), Uluru-Kata Tjuta National Park, Uluru -- 2019 -- 3704-8.jpg,
Uluru Uluru (; pjt, Uluṟu ), also known as Ayers Rock ( ) and officially Gazette#Gazette as a verb, gazetted as UluruAyers Rock, is a large sandstone geological formation, formation in the centre of Australia. It is in the southern part of the ...
, an
sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...
formation in
Australia's Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by a ...
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...
.


See also

* * * * * * * * *


Notes


References


External links

* {{Cite EB1911, wstitle=Monadnock