A panhole is a depression or basin eroded into flat or gently sloping cohesive rock.[1] Similar terms for this feature are gnamma[2] or rock holes[3] (Australia), armchair hollows, weathering pans (or pits) and solution pans (or pits).[1][4]
Panholes on a granite surface near Corscia, Corsica
Some authors[4] refer to panholes also as potholes, which is a term typically used for similarly shaped riverine landforms. In fluvial geomorphology, the term pothole is typically used for a smooth, bowl-shaped or cylindrical hollow, generally deeper than wide, found developed in the rocky bed of a stream. This type of feature is created by the grinding action either of a stone or stones or of coarse sediment whirled around and kept in motion by eddies or the force of the stream current in a given spot.[5]
Panholes are erosional or destructional features that are developed in a variety of climatic environments and in a wide range of rock types. These shallow basins, or closed depressions, are quite commonly well developed in surfaces of granitic rocks and sandstone. They are generally characterized by flat bottoms and sometimes by overhanging sides. The initial form may be a closed hollow created by a patch of humus. Diameters are rarely greater than 6 ft (1.8 m).[6] Some panholes were at one time thought to be man-made because their roundness was so perfect they were argued not be natural and must have been shaped by humans.[1][4]
Panholes are most commonly found in desert environments such as the Colorado Plateau. A few well-known panholes are found developed in sandstone surfaces in Canyonlands National Park, Capitol Reef National Park, and Moab. Panholes are capable of collecting water when it rains, freezing over when the weather gets cold, dry out in hotter weather, and can even contain some species of bacteria, lichens, mosses, and blue-green algae.[6] Panholes range in size from a few centimeters to many meters in diameter. The cavities can be shallow or more than 15 meters (49 ft) deep, containing hundreds of liters of water. The Australian Aboriginal term gnamma, in particular, implies a depression capable of holding water in arid areas, forming an important water resource for Aboriginal people that needed to be carefully maintained.[2][7]
Within the panholes is a varied eco-system that contains bacteria such as cyanobacteria, fungi, and algae which can be referred to as biofilm.[4] Panholes do not contain predators like fish or aquatic insects.[8] The biofilm breaks down some of the siliceous minerals in the panhole for nutrients resulting in furthering the weathering the panhole.[8] The organisms that live in the panholes have to tolerate rapid change in water temperature, pH, oxygen, carbon dioxide concentration, and ion concentration.[4]
In the Sierra Nevada, California these features were termed weathering pits[9] by François E. Matthes, where they are thought to indicate rock surfaces that are unglaciated or escaped more recent glaciations. In Sierra Nevada granitic rocks, these features have a characteristic shape such that they expand more rapidly in width than they grow in depth.[10] One explanation for their conformation is because the most active environment for weathering is the zone of alternate wetting and drying along the margins of the pools that collect in the pits, the margins tend to deepen and enlarge until all points of the bottom are equally wet or dry at the same time, thus producing their characteristic shape.[11] Panholes can expand from weathering and erosion but the main activity of how panholes expand is from biological weathering. At one time the belief was that the only agents involved with the expansion of panholes were physical weathering.[4]
In Australia, the terms "gnamma" and "rock hole" (or "rockhole") are used. Gnamma is an anglicization of a Nyoongar language word, used by that Aboriginal people of Western Australia to describe a naturally formed rock hole as well as its retained rainwater. The term "gnamma hole" is also widely used, but is incorrect, being a tautology.[12][3][2]
^ abcTwidale, C.R., and Bourne, J.A., 2018. Rock basins (gnammas) revisited. Géomorphologie: Relief, Processus, Environnement, Articles sous presse, Varia, mis en ligne le 08 janvier 2018, consulté le 01 juillet 2018.
^ abJonscher, Samantha (3 June 2018). "SA students take to the bush to connect with land and Indigenous culture". ABC News. Australian Broadcasting Corporation. Retrieved 9 January 2022.
^ abcdefHughes, Kebbi A., 2012. Bacterial Communities and their Influence on the Formation and Development of Potholes in Sandstone Surfaces of the Semi-Arid Colorado Plateau University of Western Ontario - Electronic Thesis and Dissertation Repository. Paper 543.
^Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds., 2011. Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 800 pp. ISBN0-922152-89-6
^ abParadise, T. R., 2013 'Tafoni and Other Rock Basins' in Treatise on Geomorphology, V.4, 111-126 doi:10.1016/B978-0-12-374739-6.00068-3
^Timms, B.V., 2013. Geomorphology of pit gnammas in southwestern Australia Journal of the Royal Society of Western Australia, 96: 7–16 Retrieved 2 November 2020.
^ abDavis, Jim, 2013. "What are “Potholes” and how are organisms able to live in them?." Utah Geological Survey. N.p., n.d. Web. 9 Oct 2013.
^Matthes, Francois E. 1930. Geologic History of the Yosemite Valley. U.S. Geological Survey Professional Paper 160
^Huber, N. King. 1989. The geological story of Yosemite National Park. U.S. Geological Survey Bulletin 1595.
^Clyde Warhaftig, attributed on page p. 63 in Huber, N. King. 1989. The geological story of Yosemite National Park. U.S. Geological Survey Bulletin 1595.
^Timms, B. V. (2013). "Geomorphology of pit gnammas in southwestern Australia" (PDF). Journal of the Royal Society of Western Australia (96): 7. Retrieved 9 January 2022.
January 01, 1970
panhole, panhole, depression, basin, eroded, into, flat, gently, sloping, cohesive, rock, similar, terms, this, feature, gnamma, rock, holes, australia, armchair, hollows, weathering, pans, pits, solution, pans, pits, granite, surface, near, corscia, corsica, . A panhole is a depression or basin eroded into flat or gently sloping cohesive rock 1 Similar terms for this feature are gnamma 2 or rock holes 3 Australia armchair hollows weathering pans or pits and solution pans or pits 1 4 Panholes on a granite surface near Corscia Corsica Some authors 4 refer to panholes also as potholes which is a term typically used for similarly shaped riverine landforms In fluvial geomorphology the term pothole is typically used for a smooth bowl shaped or cylindrical hollow generally deeper than wide found developed in the rocky bed of a stream This type of feature is created by the grinding action either of a stone or stones or of coarse sediment whirled around and kept in motion by eddies or the force of the stream current in a given spot 5 Contents 1 Description of panholes 2 Origin of panholes 3 Terminology 3 1 Australia 4 Locations 4 1 Australia 4 2 United States 5 ReferencesDescription of panholes editPanholes are erosional or destructional features that are developed in a variety of climatic environments and in a wide range of rock types These shallow basins or closed depressions are quite commonly well developed in surfaces of granitic rocks and sandstone They are generally characterized by flat bottoms and sometimes by overhanging sides The initial form may be a closed hollow created by a patch of humus Diameters are rarely greater than 6 ft 1 8 m 6 Some panholes were at one time thought to be man made because their roundness was so perfect they were argued not be natural and must have been shaped by humans 1 4 Panholes are most commonly found in desert environments such as the Colorado Plateau A few well known panholes are found developed in sandstone surfaces in Canyonlands National Park Capitol Reef National Park and Moab Panholes are capable of collecting water when it rains freezing over when the weather gets cold dry out in hotter weather and can even contain some species of bacteria lichens mosses and blue green algae 6 Panholes range in size from a few centimeters to many meters in diameter The cavities can be shallow or more than 15 meters 49 ft deep containing hundreds of liters of water The Australian Aboriginal term gnamma in particular implies a depression capable of holding water in arid areas forming an important water resource for Aboriginal people that needed to be carefully maintained 2 7 Within the panholes is a varied eco system that contains bacteria such as cyanobacteria fungi and algae which can be referred to as biofilm 4 Panholes do not contain predators like fish or aquatic insects 8 The biofilm breaks down some of the siliceous minerals in the panhole for nutrients resulting in furthering the weathering the panhole 8 The organisms that live in the panholes have to tolerate rapid change in water temperature pH oxygen carbon dioxide concentration and ion concentration 4 Origin of panholes edit nbsp Panholes in granodiorite at Glacier Point Yosemite National Park California In the Sierra Nevada California these features were termed weathering pits 9 by Francois E Matthes where they are thought to indicate rock surfaces that are unglaciated or escaped more recent glaciations In Sierra Nevada granitic rocks these features have a characteristic shape such that they expand more rapidly in width than they grow in depth 10 One explanation for their conformation is because the most active environment for weathering is the zone of alternate wetting and drying along the margins of the pools that collect in the pits the margins tend to deepen and enlarge until all points of the bottom are equally wet or dry at the same time thus producing their characteristic shape 11 Panholes can expand from weathering and erosion but the main activity of how panholes expand is from biological weathering At one time the belief was that the only agents involved with the expansion of panholes were physical weathering 4 Terminology edit nbsp Rock hole in Hiltaba Nature Reserve South Australia Australia edit In Australia the terms gnamma and rock hole or rockhole are used Gnamma is an anglicization of a Nyoongar language word used by that Aboriginal people of Western Australia to describe a naturally formed rock hole as well as its retained rainwater The term gnamma hole is also widely used but is incorrect being a tautology 12 3 2 Locations editAustralia edit Hiltaba Nature Reserve United States edit Beam Rocks Forbes State Forest Pennsylvania Canyonlands National Park Utah Glacier Point Yosemite National Park California Navajo National Monument Arizona Shenandoah National Park Virginia Stone Mountain Georgia Stone Mountain North Carolina North CarolinaReferences edit a b c Twidale C R and Bourne J A 2018 Rock basins gnammas revisited Geomorphologie Relief Processus Environnement Articles sous presse Varia mis en ligne le 08 janvier 2018 consulte le 01 juillet 2018 a b c Gnamma Holes Western Australian Museum 2017 Retrieved 5 November 2021 a b Jonscher Samantha 3 June 2018 SA students take to the bush to connect with land and Indigenous culture ABC News Australian Broadcasting Corporation Retrieved 9 January 2022 a b c d e f Hughes Kebbi A 2012 Bacterial Communities and their Influence on the Formation and Development of Potholes in Sandstone Surfaces of the Semi Arid Colorado Plateau University of Western Ontario Electronic Thesis and Dissertation Repository Paper 543 Neuendorf K K E J P Mehl Jr and J A Jackson eds 2011 Glossary of Geology 5th ed Alexandria Virginia American Geological Institute 800 pp ISBN 0 922152 89 6 a b Paradise T R 2013 Tafoni and Other Rock Basins in Treatise on Geomorphology V 4 111 126 doi 10 1016 B978 0 12 374739 6 00068 3 Timms B V 2013 Geomorphology of pit gnammas in southwestern Australia Journal of the Royal Society of Western Australia 96 7 16 Retrieved 2 November 2020 a b Davis Jim 2013 What are Potholes and how are organisms able to live in them Utah Geological Survey N p n d Web 9 Oct 2013 Matthes Francois E 1930 Geologic History of the Yosemite Valley U S Geological Survey Professional Paper 160 Huber N King 1989 The geological story of Yosemite National Park U S Geological Survey Bulletin 1595 Clyde Warhaftig attributed on page p 63 in Huber N King 1989 The geological story of Yosemite National Park U S Geological Survey Bulletin 1595 Timms B V 2013 Geomorphology of pit gnammas in southwestern Australia PDF Journal of the Royal Society of Western Australia 96 7 Retrieved 9 January 2022 Retrieved from https en wikipedia org w index php title Panhole amp oldid 1219611343, wikipedia, wiki, book, books, library,
