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 ("little head") 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.
[
]
Etymology
Inselberg
The word ''inselberg'' is a loan word 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. 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 buttes; conical hills with rectilinear sides typically found in arid regions; regolith-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 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.[ Raymo, Chet 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 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 or highland, or their remnants. This is especially the case for inselbergs composed of sedimentary rock, 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 etchplains.
Clusters of inselbergs, called inselberg fields and inselberg plains, occur in various parts of the world, including Tanzania, 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, Northeast Brazil, Namibia, the interior of Angola, and the northern portions of Finland 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; buttes, 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, gneiss and gabbro.
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 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, inside a body of softer rock such as limestone, which is more susceptible to erosion. When the less resistant rock is eroded away to form a plain, 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 sheets 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 of Tanzania and Kenya. 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 basalt in the Free State, South Africa.
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 peak formed by early Cretaceous 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.
File:Petermann Ranges (AU), Uluru-Kata Tjuta National Park, Uluru -- 2019 -- 3704-8.jpg, Uluru, an sandstone formation in Australia's Northern Territory.
See also
*
*
*
*
*
*
*
*
*
Notes
References
External links
* {{Cite EB1911, wstitle=Monadnock