From Encyclopedia Jr, free information reference for Kids
A canyon or gorge is a deep valley between cliffs often carved from the Earth by a river. Most canyons originate 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 lesser effect in arid zones. Canyons' 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 Australasia, though it is also used in some parts of the United States and Canada. The rare 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 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 course. The Colorado River and the Snake River in the northwestern United States are two examples of this.
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.
[edit] Largest canyons
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 deepest canyon in the world, Yarlung Tsangpo Canyon, along the Brahmaputra in Tibet, China, even slightly longer than Grand Canyon, is regarded by many as the world's largest canyon, followed by the Kali Gandaki Canyon in Nepal, and Polung Tsangpo Canyon in Tibet.
Slot canyons are very narrow canyons, often with smooth walls.
[edit] Well-known canyons
- Avon Gorge in Bristol, England
- Black Canyon of the Gunnison, Colorado, USA
- Canyon Fortaleza in Cambará do Sul, Brazil
- Cataract Gorge in Launceston, Australia
- Cheddar Gorge in Somerset, England
- Colca Canyon along the Colca River in Peru
- Columbia River Gorge in the Pacific Northwest of America
- Fish River Canyon in Namibia
- Glen Nevis in Lochaber, Scotland
- 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
- Itaimbezinho in Cambará do Sul, Brazil
- Kloof Gorge in Kloof, South Africa
- Malacara in Praia Grande, Brazil
- Palo Duro Canyon in Texas, USA
- Red River Gorge in Kentucky, USA
- Royal Gorge in Colorado, USA
- Tara River Canyon in Montenegro
- Three Gorges in China
- Kings Canyon in California, USA
- Vikos Gorge in Greece
- Taroko Gorge in Taiwan
Other lesser-known canyon systems include:
- Black Dragon Canyon in Utah, USA
Other canyons in the Himalayas include:
The Blue Mountains west of Sydney in New South Wales, Australia contain many canyons carved into the sandstone rock.
[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
[edit] Trivia
Despite its name, Bryce Canyon is a giant natural amphitheater created by erosion.
[edit] See also
[edit] External links
