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.
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 Denudation and lowering of the surrounding landscape.[
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Etymology
Inselberg
The word inselberg is a loan word from German language, and means "island mountain". The term was coined in 1900 by geologist Wilhelm Bornhardt (1864–1946) to describe the abundance of such features found in eastern Africa.
In a 1973 study examining the use of the term, one researcher found that the term had been used for features in savannah 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.
Monadnock
Monadnock is derived from an Abenaki language 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 in southwestern New Hampshire.[Raymo, Chet and Raymo, Maureen E. (1989) Written in Stone: A Geologic History of the Northeastern United States. Globe Pequot, Chester, Connecticut.] It is thought to derive from either menonadenak () or menadena ().[" Vermont Soils with Names of American Indian Origin " United States Department of Agriculture, Natural Resources Conservation Service. Retrieved January 6, 2008.] 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 .[Baldwin, Henry I. (1989). Monadnock Guide 4th edition. Concord, New Hampshire: Society for the Protection of New Hampshire Forests.]
Definition
The classification of Anthony Young (1969) distinguishes six types of inselbergs: , , convex-concave hills, rock crest over regolith-covered slope, granite dome (sugarloaf) and kopje or tor.
A 1972 paper defined inselbergs as "steep-sided isolated hills rising relatively abruptly above gently sloping ground". This definition includes such features as ; 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 (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.
Geology
Geological and geographical patterns
Inselbergs are common in eroded and weathered shields.
Location
Clusters of inselbergs, called inselberg fields and inselberg plains, occur in various parts of the world, including Tanzania,
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."["A Dictionary of Ecology" (2004). Encyclopedia.com. Retrieved November 28, 2009]
Inselbergs can be reshaped by much the same way as roches moutonnées. In Norrland terrain, examples of this type of inselberg are called flyggbergs.
Ecology
Inselbergs harbor unique and often endemic species from many taxonomic groups and can serve as refugia for animal species living in the surrounding matrix. Plant communities in these ecosystems are often adapted to extreme conditions such as high solar radiation and water scarcity due to the shallow and rocky soils. Since these species have a restricted distribution, they may also become severely threatened by invasive species.
The inselbergs of Eastern Africa tend to be a refuge for life in the Serengeti of Tanzania and in the Masai Mara of 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. Many animals have adapted to the use of inselbergs, including the lion, the hyrax, and an abundance of bird and reptile life.
Gallery
File:Mulanje Mountain.JPG|Mount Mulanje, a large inselberg in southeastern Malawi
File:Ledang 1.jpg|Mount Ledang, a large inselberg in the state of Johor, Malaysia
File:Kunak Sabah Mount-Madai-03.jpg|Mount Madai, Sabah, Malaysia
File:Houtkop en R26-roete, Reitz-Daniëlsrus, Vrystaat.jpg|Houtkop, a outcrop of Drakensberg basalt in the Free State, South Africa
File:Amazon jungle from above.jpg|An inselberg in the rainforest of Suriname
File:De Yalgo a Dori Marco Schmidt 0922.jpg|A duricrust 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
File:Devils Tower.jpg|Devils Tower, an archetypal example of an inselberg in Wyoming, US
File:Vinyard Knob (960) 19-10-19 996.jpg|Vinyard Knob (high point 960') in the central portion of the Knobs region
File:Bernal.jpg|Peña de Bernal in Bernal, Querétaro, México
File:Rocca di Cavour dal Monte Cucetto.jpg|Rocca di Cavour, Piedmont, Italy
File:Breast-Shaped Hill.jpg|An inselberg in Western Sahara
File:Peñón de Guatapé 02.jpg|Peñón de Guatapé, Antioquia Department, Colombia
File:Shiprock.snodgrass3.jpg|Shiprock, New Mexico
See also
Notes
External links
