Dreikanter

A dreikanter from the Wind River Basin, Wyoming, USA. Property of Western Washington University. Photo by AJ Wakefield, 2012.

A Dreikanter is a type of ventifact that typically forms in desert or periglacial environments due to the abrasive action of blowing sand.[1]

Dreikanters exhibit a characteristic three-faced pyramidal shape. The word Dreikanter is a German word meaning "three-edged."[2]

A dreikanter is not to be confused with a zweikanter, which has only two sides, or an einkanter, which has only one windblown side. [3]

Most places on the planet have several weathering processes acting at the same time, so finding good examples of Dreikanters is often difficult. Antarctica is a good location for finding such ventifacts since wind is usually the only active weathering agent. Many specimens in the Northeastern United States were formed during the Pleistocene era when the absence of vegetation made for little cover from wind-blown sediment.[4]

Common Features

Some common features of Dreikanters include fluting, high polish, sharp ridges, pits, grooves, and helical forms.[4][3]

Unusually large dreikanter of granite, Sweetwater County, Wyoming. This dreikanter measures 71 cm by 46 cm deep and 37 cm wide. Photo by Bradley, W.H., USGS (1930).[5]


Formation

In areas where there is a prevailing wind, sand and debris cause a rock face to become flattened and polished. This changes the mass distribution of the rock, and may cause it to turn another surface toward the wind. If this process continues undisturbed, the resulting rock will have three distinct flattened and polished faces.[6] Dreikanters generally form in dry, arid environments from hard rocks.[6]

See also

References

  1. ↑ Wade, A. 1910. On the formation of dreikanter in desert regions. The Geological Magazine, Decade V, 7(9):394-398.
  2. ↑ WeatherTalk - Jargon
  3. 1 2 Greeley, R., N. T. Bridges, R. O. Kuzmin, and J. E. Laity, Terrestrial analogs to wind-related features at the Viking and Pathfinder landing sites on Mars, J. Geophys. Res., 107(E1), 10.1029/2000JE001481, 2002.
  4. 1 2 Dutch, Steven. "Wind Erosion". University of Wisconsin. Retrieved 10 October 2012.
  5. ↑ U.S. Geological Survey Photographic Library ( http://libraryphoto.cr.usgs.gov/ )
  6. 1 2 "Ventifact (stone)". Britannica Online Encyclopedia. Retrieved 10 October 2012.

External links


This article is issued from Wikipedia - version of the Friday, January 15, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.