Canyon
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- For the song, see CANYON.MID. For the band, see Canyon (band).
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A canyon (rarely cañon) or gorge is a deep valley between cliffs often carved from the landscape by a river. Most canyons were formed by a process of long-time erosion from a plateau level. The cliffs form because harder rock strata that are 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 greater effect in arid zones. Canyon walls are often formed of resistant sandstones or granite. Submarine canyons are those which form underwater, generally at the mouths of rivers. The word canyon is Spanish in origin (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 military derived word defile is occasionally used in England.
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, Ancient Pueblo Peoples.
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.
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.
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[edit] Largest canyons
- Grand Canyon in Arizona, USA
- Copper Canyon in Chihuahua, Mexico
The definition of "largest canyon" is rather imprecise, as a canyon can be "large" by its depth, length, or the total area of the canyon system. Also the inaccessibility of the major canyons in the Himalaya contributes to their not being regarded as candidates for the biggest canyon. The definition of "deepest canyon" is similarly imprecise, especially if one includes mountain canyons as well as canyons cut through relatively flat plateaus (which have a somewhat well-defined rim elevation).
The Yarlung Tsangpo Canyon, along the Yarlung Tsangpo River in Tibet, China, is regarded by some as the deepest canyon in the world, and 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[1] in Nepal, Polung Tsangpo Canyon in Tibet, Cotahuasi Canyon (3,535 m deep and the deepest in the Americas), and the Tekezé gorge (2000m+ deep and deepest in Africa).[2]
Slot canyons are very narrow canyons, often with smooth walls.
[edit] Other well-known canyons
- Avon Gorge in Bristol, England
- Blyde River Canyon in Mpumalanga, South Africa
- Black Canyon of the Gunnison, Colorado, USA
- Canyon Fortaleza in Cambará do Sul, Brazil
- Canhão da Nazaré, Portugal
- Canyon Guartelá in Tibagi, Brazil
- Sumidero Canyon in Chiapas, Mexico
- Cataract Gorge in Launceston, Australia
- Cheddar Gorge in Somerset, England
- 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.
- Cotahuasi Canyon along the Cotahuasi River in Arequipa, Peru, the deepest canyon in the world with 3535 meters.
- Fish River Canyon in Namibia
- Glen Nevis in Lochaber, Scotland
- Grand Canyon of Pennsylvania located in the Tioga State Forest in Pennsylvania, USA
- Grand Canyon of the Yellowstone located within Yellowstone National Park in Wyoming, USA
- Grand Canyon du Verdon in Provence, France
- Gorges d'Ardèche, in France
- Gorges du Tarn in France
- Hells Canyon in Idaho and Oregon, USA
- Ironbridge Gorge in Shropshire, England
- Iron Gate located in the Đerdap national park in Serbia
- Itaimbezinho in Cambará do Sul, Brazil
- Kloof Gorge in Kloof, South Africa
- Komati Gorge, South Africa
- Lanner Gorge, South Africa
- Malacara in Praia Grande, Brazil
- Nine Mile Canyon in eastern Utah, USA
- Palo Duro Canyon in Texas, USA
- Pankisi Gorge in Georgia (country)
- Red River Gorge in Kentucky, USA
- Royal Gorge in Colorado, USA
- Samaria Gorge in Crete, Greece
- São Francisco River Canyon, Brazil
- Tara River Canyon in Montenegro
- Taroko Gorge in Taiwan
- Three Gorges in China
- Kings Canyon in California, USA
- Vikos Gorge in Greece
- Galston Gorge in NSW, Australia
Other lesser-known canyon systems include:
- Black Dragon Canyon in Utah, USA
- Manawatu Gorge in Manawatu, North Island New Zealand
- Swaan River makes many gorges in Pothohar plateau Pakistan.
- Four canyons in the Nahanni, Canada, the largest being 19km long and 1.2km deep.[1]
The Blue Mountains west of Sydney in New South Wales, Australia contain many
[edit] 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
Venus has many craters and canyons on its surface. The troughs on the planet are part of a system of canyons that is more than 6 400 km long.
[edit] See also
[edit] Notes
- ^ 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 metres and 2600 metres, 5500 to 6800 metres 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 Google Earth.
- ^ Ethiopia's Water Dilemma http://www.internationalrivers.org/en/africa/world-rivers-review-vol-21-no-4-august-2006-focus-africa]PDF (1.58 MiB)
