Difference between revisions of "Canyon" - New World Encyclopedia

From New World Encyclopedia
m
(14 intermediate revisions by 6 users not shown)
Line 1: Line 1:
{{Claimed}}
+
{{Images OK}}{{Submitted}}{{Approved}}{{Paid}}{{Copyedited}}
 
[[image:Grand_Canyon.jpg.jpg|right|thumb|250px|[[Grand Canyon]], [[Arizona]].]]
 
[[image:Grand_Canyon.jpg.jpg|right|thumb|250px|[[Grand Canyon]], [[Arizona]].]]
[[Image:Noravank_with_cliffs-DCP_0186.JPG|thumb|300px|right|[[Noravank Monastery]] complex and canyon in [[Armenia]].]]
 
  
A '''canyon''' or '''gorge''' is a deep valley between [[cliff]]s, often carved from the landscape by a [[river]]. A famous example is the [[Grand Canyon]] in [[Arizona]]. In the southwestern United States, canyons are important [[archeology|archeologically]] because of the many [[cliff-dwelling]]s built there, largely by the earlier inhabitants, [[Ancient Pueblo Peoples]].
+
A '''canyon''' or '''gorge''' is a deep valley between [[cliff]]s, often carved from the landscape by a [[river]]. A famous example is the [[Grand Canyon]] in [[Arizona]]. In the southwestern United States, canyons are important [[archeology|archeologically]] because of the many [[cliff-dwelling]]s built there, largely by the earlier inhabitants, the [[ancient Pueblo Peoples]].
 
+
{{toc}}
A '''submarine canyon''' is a steep-sided [[valley]] on the [[sea floor]] of the [[continental slope]]. Many submarine canyons are found as extensions to large rivers, but many others have no such association. Canyons cutting the continental slopes have been found at depths greater than two kilometers below sea level. They are formed by powerful turbidity currents, volcanic and earthquake activity. Many submarine canyons continue as submarine channels across continental rise areas and may extend for hundreds of kilometers.  
+
A '''submarine canyon''' is a steep-sided [[valley]] on the [[sea floor]] of the [[continental slope]]. Many submarine canyons are found as extensions to large rivers, but many others have no such association. Canyons cutting the continental slopes have been found at depths greater than two kilometers below sea level. They are formed by powerful turbidity currents, [[volcano|volcanic]] and [[earthquake]] activity. Many submarine canyons continue as submarine channels across continental rise areas and may extend for hundreds of kilometers.
  
 
== Terminology ==
 
== Terminology ==
 +
[[Image:Noravank_with_cliffs-DCP_0186.JPG|thumb|300px|right|[[Noravank Monastery]] complex and canyon in [[Armenia]].]]
 +
The word ''canyon'' derives from the Spanish word ''(cañón)''. The word ''canyon'' is generally used in the [[United States]], while the word ''gorge'' is more common in [[Europe]] and [[Oceania]], though it is also used in some parts of the United States and [[Canada]]. The word ''defile'' is occasionally used in England, to signify a narrow gorge.
  
The word ''canyon'' derives from the Spanish word ''(cañón)''. The word ''canyon'' is generally used in the [[United States]], while the word ''gorge'' is more common in [[Europe]] and [[Oceania]], though it is also used in some parts of the United States and [[Canada]]. The rare word ''defile'' is occasionally used in England.
+
[[Image:Lower_antelope_1_md.jpg|thumb|right|240px|A portion of Lower Antelope Canyon, a slot canyon near Page, Arizona.]]
  
 +
'''Slot canyons''' are very narrow canyons, often with smooth walls. Some slot canyons can measure less than one meter (3 feet) across at the top but drop more than 30 m (100 ft) to the floor of the canyon.
  
Sometimes large rivers run through canyons as the result of gradual geologic uplift.  These are called [[entrenched river]]s, because they are unable to easily alter their course.  The [[Colorado River (U.S.)|Colorado River]] and the [[Snake River]] in the northwestern [[United States]] are two examples of [[tectonic uplift]].
+
== Formation of canyons on land ==
 
+
Most canyons were formed by a process of long-time [[erosion]] from a [[plateau]] level. Canyons often form in areas of [[limestone]] rock. Limestone is to a certain extent soluble, so [[cave]] systems form in the rock. When these collapse a canyon is left, for example in the [[Mendip Hills]] in [[Somerset]] and [[Yorkshire Dales]] in [[Yorkshire]], [[England]].
Canyons often form in areas of [[limestone]] rock. Limestone is to a certain extent soluble, so [[cave]] systems form in the rock. When these collapse a canyon is left, for example in the [[Mendip Hills]] in [[Somerset]] and [[Yorkshire Dales]] in [[Yorkshire]], [[England]].
 
  
==Largest canyons==
+
The cliffs often consist of harder [[rock (geology)|rock]] strata, such as [[sandstone]]s or [[granite]], that are [[resistance (geology)|resistant]] to erosion and weathering. Canyons are much more common in arid areas than in wetter areas because weathering has a lesser effect in arid zones.
  
The [[Grand Canyon]] in [[Arizona]], [[United States]], and the [[Copper Canyon]] in [[Chihuahua State|Chihuahua]], [[Mexico]] are two of the largest canyons in the world. Yet, the definition of "largest canyon" is rather imprecise, because a canyon system can be "large" in terms of its depth, length, or total area of the system. The definition of "deepest canyon" is similarly imprecise, especially if one includes mountain canyons as well as canyons that cut through relatively flat [[plateau]]s (which have a somewhat well-defined rim elevation). The inaccessibility of the major canyons in the [[Himalaya]] mountain range is one reason why they are usually not regarded as candidates for the biggest canyon.
+
Sometimes large rivers run through canyons as the result of gradual geologic uplift. These are called [[entrenched river]]s, because they are unable to easily alter their course. The [[Colorado River (U.S.)|Colorado River]] and the [[Snake River]] in the northwestern [[United States]] are two examples of [[tectonic uplift]].
  
The [[Yarlung Tsangpo Canyon]], along the [[Yarlung Tsangpo River (Tibet)|Yarlung Tsangpo River]] in [[Tibet]], is regarded by some as the deepest canyon in the world, and it is even slightly longer than Grand Canyon. Hence it is regarded by many as the world's largest canyon, followed by the [[Kali Gandaki|Kali Gandaki Gorge]]<ref name="kali_gandaki_deepest">If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, the Kali Gandaki Gorge is the world's deepest. The portion of the river between the [[Dhaulagiri]] and [[Annapurna]] massifs is at an elevation of between 1300 meters and 2600 meters, 5500 to 6800 meters lower than the two peaks. See ''Annapurna'' (1:100,000 map), Nepal-Kartenwerk der Arbeitgemeinschaft für vergleichende Hochgebirgsforschung Nr. 9, Nelles Verlag, Munich, 1993. Also see [http://earth.google.com Google Earth].</ref> in [[Nepal]], [[Polung Tsangpo Canyon]] in Tibet, [[Cotahuasi Canyon]] (3,535 m deep and the deepest in the Americas), and the [[Tekezé River|Tekezé gorge]] (2000m+ deep and deepest in Africa).<ref>[http://www.irn.org/pubs/wrr/issues/WRR.V21.N4.pdf Ethiopia's Water Dilemma.] ''World Rivers Review, August 2006.'' (pdf) Retrieved October 12, 2007.</ref>
+
=== Formation of slot canyons ===
 +
Slot canyons are found in many parts of the world, predominantly in areas with low rainfall. They are formed by the wear of water rushing through rock. Most slot canyons are formed in [[sandstone]] and [[limestone]] rock, although some have also been formed in other rock types such as [[granite]] and [[basalt]]. Even in sandstone and limestone, only a very small number of [[steam|creek]]s have formed slot canyons, based on a combination of the particular characteristics of the rock and regional rainfall.
  
[[Slot canyon]]s are very narrow canyons, often with smooth walls.
+
==Formation of submarine canyons==
 +
Submarine canyons are more common on steep slopes than on gentle slopes. They show erosion through all substrates, from unlithified sediment to crystalline rock. Various mechanisms have been proposed for the formation of these canyons, and they were subject to active debate, especially during the 1940s and 1950s.
  
== Submarine canyons ==
+
An early theory was that they were carved during [[glaciation|glacial]] times, when the [[sea level]] was about 200 meters below what it is today, and rivers flowed to the edge of the continental shelf. Indeed, many (but not all) canyons are found offshore from major rivers. Yet, this mechanism cannot explain erosion reaching water depths as great as 3,000 meters, where canyons have been mapped. It has been well established (by many lines of evidence) that sea levels did not fall to those depths.
  
 +
It is now understood that several mechanisms have contributed to submarine canyon formation and development, even within the same canyon. The major mechanism of canyon erosion is now thought to be [[turbidity current]]s and underwater landslides. Turbidity currents are dense, sediment-laden currents that flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by [[earthquake]]s. There is a spectrum of turbidity- or density-current types ranging from "muddy water" to massive mudflow, and evidence for both these end members can be found in deposits associated with the deeper parts of submarine canyons and channels.
  
==Characteristics==
+
[[Mass wasting]], slumping, and submarine [[landslide]]s are forms of slope failures (the effect of gravity on a hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action of material moving downhill; and would commonly include the effects of [[bioerosion]]: the burrowing, ingestion, and defecation of sediment by living organisms. Slumping generally refers to rotational movement of masses on a hillside. Landslides, or slides, generally consist of the detachment and displacement of sediment masses. All are observed and are contributory processes.
  
Submarine canyons are more common on steep slopes than on gentle slopes.  They show erosion through all substrates, from unlithified sediment to crystalline rock.  They are more densely spaced on steep slopes while being rare on gentle slopes.  The walls are generally very steep and can be near vertical.  The walls are subject to erosion by [[turbidity current]]s, [[bioerosion]], or [[slumping]].
+
==Largest canyons on land==
 
+
The [[Grand Canyon]] in [[Arizona]], [[United States]], and the [[Copper Canyon]] in [[Chihuahua State|Chihuahua]], [[Mexico]] are two of the largest canyons in the world. Yet, the definition of "largest canyon" is rather imprecise, because a canyon system can be "large" in terms of its depth, length, or total area of the system. The definition of "deepest canyon" is similarly imprecise, especially if one includes mountain canyons as well as canyons that cut through relatively flat [[plateau]]s (which have a somewhat well-defined rim elevation). The inaccessibility of the major canyons in the [[Himalaya]] mountain range is one reason why they are usually not regarded as candidates for the biggest canyon.
== Formation of canyons on land ==
 
 
 
Most canyons were formed by a process of long-time [[erosion]] from a [[plateau]] level. The cliffs are formed because harder [[rock (geology)|rock]] strata that are [[resistance (geology)|resistant]] to erosion and weathering remain exposed on the valley walls. Canyons are much more common in arid areas than in wetter areas because weathering has a lesser effect in arid zones. Canyon walls are often formed of resistant [[sandstone]]s or [[granite]].
 
  
==Formation of submarine canyons==
+
The [[Yarlung Tsangpo Canyon]], along the [[Yarlung Tsangpo River (Tibet)|Yarlung Tsangpo River]] in [[Tibet]], is regarded by some as the deepest canyon in the world, and it is even slightly longer than Grand Canyon. Hence, it is regarded by many as the world's largest canyon, followed by the [[Kali Gandaki|Kali Gandaki Gorge]]. If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, the Kali Gandaki Gorge is the world's deepest. The portion of the river between the [[Dhaulagiri]] and [[Annapurna]] massifs is at an elevation of between 1,300 meters and 2,600 meters, 5,500 to 6,800 meters lower than the two peaks<ref>"Annapurna" (1:100,000 map), ''Nepal-Kartenwerk der Arbeitgemeinschaft für vergleichende Hochgebirgsforschung Nr. 9'', Nelles Verlag, Munich, 1993.</ref> in [[Nepal]], [[Polung Tsangpo Canyon]] in Tibet, [[Cotahuasi Canyon]] (3,535 m deep and the deepest in the Americas), and the [[Tekezé River|Tekezé gorge]] (2,000m+ deep, and deepest in Africa).<ref>[http://www.irn.org/pubs/wrr/issues/WRR.V21.N4.pdf Ethiopia's Water Dilemma.] ''World Rivers Review, August 2006.'' (pdf) Retrieved October 12, 2007.</ref>
  
Many mechanisms have been proposed for the formation of submarine canyons, and during the 1940s and 1950s the primary causes of submarine canyons were subject to active debate.
+
== Examples of slot canyons ==
 +
[[Image:Paria UT-5.jpg|thumb|right|240px|Wire Pass leading into [[Buckskin Gulch]], the longest slot canyon in the world, near Kanab, Utah.]]
  
An early and obvious theory was that the canyons present today were carved during [[glaciation|glacial]] times, when [[sea level]] was about 200 meters below present sea level, and rivers flowed to the edge of the continental shelf. However, while many (but not all) canyons are found offshore from major rivers, subaerial river erosion cannot have been active to the water depths as great as 3000 meters where canyons have been mapped, as it is well established (by many lines of evidence) that sea levels did not fall to those depths.
+
Some of the most well-known slot canyons are found in the southwestern [[United States]]. Other significant areas include the [[Sierra de Guara]] in northern [[Spain]], the [[Pyrenees]] on the border of [[France]] and Spain, and the [[Blue Mountains]] in [[New South Wales]], [[Australia]].
  
The major mechanism of canyon erosion is now thought to be [[turbidity current]]s and underwater landslides. Turbidity currents are dense, sediment-laden currents which flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by [[earthquake]]s. There is a spectrum of turbidity- or density-current types ranging from "muddy water" to massive mudflow, and evidence of both these end members can be observed in deposits associated with the deeper parts of submarine canyons and channels, such as [[lobate]] deposits (mudflow) and levees along channels.
+
===United States===
 +
The state of [[Utah]] in the [[United States]] has the largest concentration of slot canyons in the world.<ref>[http://www.zionnational-park.com/slots.htm Zion slot canyons], Zion National-Park  dot com, 2007. Retrieved October 18, 2007.</ref> [[Antelope Canyon]], one of the most famous of the slot canyons, is located in [[Arizona]] near [[Page, Arizona|Page]], on the [[Navajo Nation|Navajo]] reservation. There are also numerous slot canyons in the valley between [[U.S. Route 89#Arizona|US Route 89]] and the [[Vermilion Cliffs]] in Arizona, and can be seen as one descends into the valley on US 89, but they too are on the [[Navajo]] reservation and are closed to the public. Several canyons accessible to the public are within [[Zion National Park]] and [[Death Valley National Park]].
  
[[Mass wasting]], slumping, and submarine [[landslide]]s are forms of slope failures (the effect of gravity on a hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action of material moving downhill; and would commonly include the effects of [[bioerosion]]: the burrowing, ingestion and defecation of sediment performed by organisms. Slumping is generally used for rotational movement of masses on a hillside. Landslides, or slides, generally comprise the detachment and displacement of sediment masses. All are observed; all are contributory processes.
+
===Australia===
 +
The largest known area of slot canyons in [[Australia]] is in the [[Blue Mountains]], west of [[Sydney]]. They occur in a narrow band of sandstone that runs roughly 30 km (19 mi) from east to west, and about 100 km (62 mi) from south to north. The majority of these canyons are in the [[Wollemi National Park|Wollemi Wilderness]] and are difficult to access. A small number are regularly visited by canyoners on weekends in summer.
  
It is now understood that many mechanisms of submarine canyon creation have had effect to greater or lesser degree in different places, even within the same canyon, or at different times during a canyon's development. However, if a primary mechanism must be selected, the downslope lineal morphology of canyons and channels and the transportation of excavated or loose materials of the continental slope over extensive distances require that various kinds of turbidity or density currents act as major participants.
+
Sandstone slot canyons can also be found in a few more remote parts of Australia, including:
 +
* the [[Bungle Bungles]] in [[Purnululu National Park]], [[Western Australia]]
 +
* [[Karijini National Park]] in Western Australia
 +
* [[Carnarvon Gorge]] in [[Queensland]]
  
 
7777777
 
 
==Other well-known canyons==
 
==Other well-known canyons==
 
*[[Avon Gorge]] in [[Bristol]], [[England]]
 
*[[Avon Gorge]] in [[Bristol]], [[England]]
Line 61: Line 66:
 
*[[Colca Canyon]] along the [[Colca River]] in [[Arequipa]], [[Peru]] one of the deepest canyons in the world with 3269 [[meters]].
 
*[[Colca Canyon]] along the [[Colca River]] in [[Arequipa]], [[Peru]] one of the deepest canyons in the world with 3269 [[meters]].
 
*[[Columbia River Gorge]] in the [[Pacific Northwest]] of America.
 
*[[Columbia River Gorge]] in the [[Pacific Northwest]] of America.
*[[Cotahuasi Canyon]] along the [[Cotahuasi River]] in [[Arequipa]], [[Peru]], the deepest canyon in the world with 3535 [[meters]].
+
*[[Cotahuasi Canyon]] along the [[Cotahuasi River]] in [[Arequipa]], [[Peru]], the deepest canyon in the world with 3535 [[meters]].
 
*[[Fish River Canyon]] in [[Namibia]]
 
*[[Fish River Canyon]] in [[Namibia]]
 
*[[Glen Nevis]] in [[Lochaber]], [[Scotland]]
 
*[[Glen Nevis]] in [[Lochaber]], [[Scotland]]
Line 87: Line 92:
 
*[[Vikos Gorge]] in [[Greece]]
 
*[[Vikos Gorge]] in [[Greece]]
  
Other lesser-known canyon systems include:
+
Some lesser-known canyon systems are:
 
*[[Black Dragon Canyon]] in [[Utah]], [[USA]]
 
*[[Black Dragon Canyon]] in [[Utah]], [[USA]]
 
*[[Swaan River]] makes many gorges in [[Pothohar]] plateau [[Pakistan]].
 
*[[Swaan River]] makes many gorges in [[Pothohar]] plateau [[Pakistan]].
The [[Blue Mountains]] west of [[Sydney]] in [[New South Wales]], [[Australia]] contain many gorges carved into the [[sandstone]] rock.
+
* Gorges in the [[sandstone]] rock of the [[Blue Mountains]] west of [[Sydney]] in [[New South Wales]], [[Australia]].
  
 
==Examples of submarine canyons==
 
==Examples of submarine canyons==
* [[Congo canyon]], the largest river canyon, extending from the [[Congo river]], is 800 km (500 miles) long, and 1,200m (4000 ft) deep.
+
* [[Congo canyon]], the largest river canyon, extending from the [[Congo river]], is 800 km (500 miles) long and 1,200m (4000 ft) deep.
 
* [[Amazon canyon]], extending from the [[Amazon river]]
 
* [[Amazon canyon]], extending from the [[Amazon river]]
* [[Hudson canyon]][http://oceanexplorer.noaa.gov/explorations/02hudson/background/mapping/media/elevation.html], extending from the [[Hudson river]]  
+
* [[Hudson canyon]]<ref>[http://oceanexplorer.noaa.gov/explorations/02hudson/background/mapping/media/elevation.html Hadson canyon], Ocean Explorer, 2005. Retrieved October 18, 2007.</ref> extending from the [[Hudson river]]  
 
* [[Ganges canyon]], extending from the [[Ganges river]]
 
* [[Ganges canyon]], extending from the [[Ganges river]]
 
* [[Indus canyon]], extending from the [[Indus river]]
 
* [[Indus canyon]], extending from the [[Indus river]]
Line 109: Line 114:
  
 
==See also==
 
==See also==
 
 
*[[Geomorphology]]
 
*[[Geomorphology]]
 
*[[Geology]]
 
*[[Geology]]
Line 118: Line 122:
  
 
== References ==
 
== References ==
 
 
* Abbott, Lon, and Terri Cook. 2004. ''Hiking the Grand Canyon's Geology.'' Seattle, WA: Mountaineers Books. ISBN 0898868955.
 
* Abbott, Lon, and Terri Cook. 2004. ''Hiking the Grand Canyon's Geology.'' Seattle, WA: Mountaineers Books. ISBN 0898868955.
 
 
* Beus, Stanley S., and Michael Morales. 2003. ''Grand Canyon Geology.'' 2nd ed. New York: Oxford University Press. ISBN 0195122992.
 
* Beus, Stanley S., and Michael Morales. 2003. ''Grand Canyon Geology.'' 2nd ed. New York: Oxford University Press. ISBN 0195122992.
 
 
* Erickson, Jon. 2001. ''Rock Formations and Unusual Geologic Structures.'' Exploring the Earth's Surface. New York: Facts on File. ISBN 0816043280.
 
* Erickson, Jon. 2001. ''Rock Formations and Unusual Geologic Structures.'' Exploring the Earth's Surface. New York: Facts on File. ISBN 0816043280.
 
 
* Plummer, Charles C., David McGeary, and Diane H. Carlson. 2005. ''Physical Geology.'' Boston: McGraw-Hill. ISBN 007252815X.
 
* Plummer, Charles C., David McGeary, and Diane H. Carlson. 2005. ''Physical Geology.'' Boston: McGraw-Hill. ISBN 007252815X.
 
 
* Whitney, Stephen. 1996. ''A Field Guide to the Grand Canyon.'' Seattle, WA: Mountaineers. ISBN 0898864895.
 
* Whitney, Stephen. 1996. ''A Field Guide to the Grand Canyon.'' Seattle, WA: Mountaineers. ISBN 0898864895.
  
 
==External links==
 
==External links==
All links retrieved September 29, 2007.
+
All links retrieved January 9, 2017.
* [http://www.canyonsworldwide.com/index.html Grand Canyons of Earth.] ''canyonsworldwide.com''.
+
 
* [http://www.friendsoftheravines.org Friends of the Ravines]
+
* [http://www.friendsoftheravines.org Friends of the Ravines]  
* [http://balashon.blogspot.com/2006/06/canyon.html Etymology of "canyon"]
+
* [http://www.cotahuasicanyon.com Cotahuasi Canyon]  
* [http://www.linuxchris.com/thumbnails.php?album=37 Pictures of a smaller Gorge in Jeffersonville, VT]
+
*[http://www.zionnational-park.com/zion-national-park-canyoneering.htm Zion National Park Canyoneering.]  
* [http://www.cotahuasicanyon.com Cotahuasi Canyon]
+
*[http://www.zionnational-park.com/slots.htm Southern Utah's Slot Canyons]  
*[http://www.abdn.ac.uk/turbidites/modern_c.html Modern deep-water canyons]
+
*[http://www.americansouthwest.net/slot_canyons/index.html Slot Canyons of the American Southwest]
  
 
[[Category:Physical sciences]]
 
[[Category:Physical sciences]]
Line 142: Line 141:
 
[[Category:Geology]]
 
[[Category:Geology]]
  
{{credits|160491152}}
+
{{credits|Canyon|160491152|Submarine_canyon|157143335|Slot_canyon|155822882}}

Revision as of 16:35, 9 January 2017

A canyon or gorge is a deep valley between cliffs, often carved from the landscape by a river. A famous example is the Grand Canyon in Arizona. In the southwestern United States, canyons are important archeologically because of the many cliff-dwellings built there, largely by the earlier inhabitants, the ancient Pueblo Peoples.

A submarine canyon is a steep-sided valley on the sea floor of the continental slope. Many submarine canyons are found as extensions to large rivers, but many others have no such association. Canyons cutting the continental slopes have been found at depths greater than two kilometers below sea level. They are formed by powerful turbidity currents, volcanic and earthquake activity. Many submarine canyons continue as submarine channels across continental rise areas and may extend for hundreds of kilometers.

Terminology

Noravank Monastery complex and canyon in Armenia.

The word canyon derives from the Spanish word (cañón). The word canyon is generally used in the United States, while the word gorge is more common in Europe and Oceania, though it is also used in some parts of the United States and Canada. The word defile is occasionally used in England, to signify a narrow gorge.

A portion of Lower Antelope Canyon, a slot canyon near Page, Arizona.

Slot canyons are very narrow canyons, often with smooth walls. Some slot canyons can measure less than one meter (3 feet) across at the top but drop more than 30 m (100 ft) to the floor of the canyon.

Formation of canyons on land

Most canyons were formed by a process of long-time erosion from a plateau level. Canyons often form in areas of limestone rock. Limestone is to a certain extent soluble, so cave systems form in the rock. When these collapse a canyon is left, for example in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire, England.

The cliffs often consist of harder rock strata, such as sandstones or granite, that are resistant to erosion and weathering. Canyons are much more common in arid areas than in wetter areas because weathering has a lesser effect in arid zones.

Sometimes large rivers run through canyons as the result of gradual geologic uplift. These are called entrenched rivers, because they are unable to easily alter their course. The Colorado River and the Snake River in the northwestern United States are two examples of tectonic uplift.

Formation of slot canyons

Slot canyons are found in many parts of the world, predominantly in areas with low rainfall. They are formed by the wear of water rushing through rock. Most slot canyons are formed in sandstone and limestone rock, although some have also been formed in other rock types such as granite and basalt. Even in sandstone and limestone, only a very small number of creeks have formed slot canyons, based on a combination of the particular characteristics of the rock and regional rainfall.

Formation of submarine canyons

Submarine canyons are more common on steep slopes than on gentle slopes. They show erosion through all substrates, from unlithified sediment to crystalline rock. Various mechanisms have been proposed for the formation of these canyons, and they were subject to active debate, especially during the 1940s and 1950s.

An early theory was that they were carved during glacial times, when the sea level was about 200 meters below what it is today, and rivers flowed to the edge of the continental shelf. Indeed, many (but not all) canyons are found offshore from major rivers. Yet, this mechanism cannot explain erosion reaching water depths as great as 3,000 meters, where canyons have been mapped. It has been well established (by many lines of evidence) that sea levels did not fall to those depths.

It is now understood that several mechanisms have contributed to submarine canyon formation and development, even within the same canyon. The major mechanism of canyon erosion is now thought to be turbidity currents and underwater landslides. Turbidity currents are dense, sediment-laden currents that flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes. There is a spectrum of turbidity- or density-current types ranging from "muddy water" to massive mudflow, and evidence for both these end members can be found in deposits associated with the deeper parts of submarine canyons and channels.

Mass wasting, slumping, and submarine landslides are forms of slope failures (the effect of gravity on a hillslope) observed in submarine canyons. Mass wasting is the term used for the slower and smaller action of material moving downhill; and would commonly include the effects of bioerosion: the burrowing, ingestion, and defecation of sediment by living organisms. Slumping generally refers to rotational movement of masses on a hillside. Landslides, or slides, generally consist of the detachment and displacement of sediment masses. All are observed and are contributory processes.

Largest canyons on land

The Grand Canyon in Arizona, United States, and the Copper Canyon in Chihuahua, Mexico are two of the largest canyons in the world. Yet, the definition of "largest canyon" is rather imprecise, because a canyon system can be "large" in terms of its depth, length, or total area of the system. The definition of "deepest canyon" is similarly imprecise, especially if one includes mountain canyons as well as canyons that cut through relatively flat plateaus (which have a somewhat well-defined rim elevation). The inaccessibility of the major canyons in the Himalaya mountain range is one reason why they are usually not regarded as candidates for the biggest canyon.

The Yarlung Tsangpo Canyon, along the Yarlung Tsangpo River in Tibet, is regarded by some as the deepest canyon in the world, and it is even slightly longer than Grand Canyon. Hence, it is regarded by many as the world's largest canyon, followed by the Kali Gandaki Gorge. If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, the Kali Gandaki Gorge is the world's deepest. The portion of the river between the Dhaulagiri and Annapurna massifs is at an elevation of between 1,300 meters and 2,600 meters, 5,500 to 6,800 meters lower than the two peaks[1] in Nepal, Polung Tsangpo Canyon in Tibet, Cotahuasi Canyon (3,535 m deep and the deepest in the Americas), and the Tekezé gorge (2,000m+ deep, and deepest in Africa).[2]

Examples of slot canyons

Wire Pass leading into Buckskin Gulch, the longest slot canyon in the world, near Kanab, Utah.

Some of the most well-known slot canyons are found in the southwestern United States. Other significant areas include the Sierra de Guara in northern Spain, the Pyrenees on the border of France and Spain, and the Blue Mountains in New South Wales, Australia.

United States

The state of Utah in the United States has the largest concentration of slot canyons in the world.[3] Antelope Canyon, one of the most famous of the slot canyons, is located in Arizona near Page, on the Navajo reservation. There are also numerous slot canyons in the valley between US Route 89 and the Vermilion Cliffs in Arizona, and can be seen as one descends into the valley on US 89, but they too are on the Navajo reservation and are closed to the public. Several canyons accessible to the public are within Zion National Park and Death Valley National Park.

Australia

The largest known area of slot canyons in Australia is in the Blue Mountains, west of Sydney. They occur in a narrow band of sandstone that runs roughly 30 km (19 mi) from east to west, and about 100 km (62 mi) from south to north. The majority of these canyons are in the Wollemi Wilderness and are difficult to access. A small number are regularly visited by canyoners on weekends in summer.

Sandstone slot canyons can also be found in a few more remote parts of Australia, including:

  • the Bungle Bungles in Purnululu National Park, Western Australia
  • Karijini National Park in Western Australia
  • Carnarvon Gorge in Queensland

Other well-known canyons

Some lesser-known canyon systems are:

Examples of submarine canyons

  • Congo canyon, the largest river canyon, extending from the Congo river, is 800 km (500 miles) long and 1,200m (4000 ft) deep.
  • Amazon canyon, extending from the Amazon river
  • Hudson canyon[4] extending from the Hudson river
  • Ganges canyon, extending from the Ganges river
  • Indus canyon, extending from the Indus river
  • Monterey Canyon, off the coast of central California
  • La Jolla and Scripps canyon, off the coast of La Jolla, southern California
  • Whittard Canyon, Atlantic Ocean off southwest Ireland
  • Bering Canyon, in the Bering sea
  • Zhemchug Canyon the largest submarine canyon in the world, also in the Bering sea.

Canyons on other planetary bodies

  • Valles Marineris on Mars is the largest known canyon in the solar system
  • Ithaca Chasma on Saturn's moon Tethys

See also

Notes

  1. "Annapurna" (1:100,000 map), Nepal-Kartenwerk der Arbeitgemeinschaft für vergleichende Hochgebirgsforschung Nr. 9, Nelles Verlag, Munich, 1993.
  2. Ethiopia's Water Dilemma. World Rivers Review, August 2006. (pdf) Retrieved October 12, 2007.
  3. Zion slot canyons, Zion National-Park dot com, 2007. Retrieved October 18, 2007.
  4. Hadson canyon, Ocean Explorer, 2005. Retrieved October 18, 2007.

References
ISBN links support NWE through referral fees

  • Abbott, Lon, and Terri Cook. 2004. Hiking the Grand Canyon's Geology. Seattle, WA: Mountaineers Books. ISBN 0898868955.
  • Beus, Stanley S., and Michael Morales. 2003. Grand Canyon Geology. 2nd ed. New York: Oxford University Press. ISBN 0195122992.
  • Erickson, Jon. 2001. Rock Formations and Unusual Geologic Structures. Exploring the Earth's Surface. New York: Facts on File. ISBN 0816043280.
  • Plummer, Charles C., David McGeary, and Diane H. Carlson. 2005. Physical Geology. Boston: McGraw-Hill. ISBN 007252815X.
  • Whitney, Stephen. 1996. A Field Guide to the Grand Canyon. Seattle, WA: Mountaineers. ISBN 0898864895.

External links

All links retrieved January 9, 2017.

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.