A canyon (from Spanish : cañón; archaic British English spelling: cañon) or gorge is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering.
A canyon may also refer to a rift between two mountain peaks, such as those in ranges including the Rocky Mountains, the Alps, the Himalayas or the Andes. Usually, a river or stream carves out such splits between mountains. Examples of mountain-type canyons are Provo Canyon in Utah or Yosemite Valley in California's Sierra Nevada. Canyons within mountains, or gorges that have an opening on only one side, are called box canyons. Slot canyons are very narrow canyons that often have smooth walls.Chakwal Canyons in PAKISTAN are famous for their unique beauty of standing beside Dharabi Dam.TDCP (Tourism Development corporation of Pakistan )conduct visit to CHAKWAL CANYON regularly.
Steep-sided valleys in the seabed of the continental slope are referred to as submarine canyons. Unlike canyons on land, submarine canyons are thought to be formed by turbidity currents and landslides.
The word canyon is Spanish in origin (cañón, [kaˈɲon] ), with the same meaning. The word canyon is generally used in North America, while the words gorge and ravine (French in origin) are used in Europe and Oceania, though gorge and ravine are also used in some parts of North America. In the United States, place names generally use canyon in the southwest (due to their proximity to Spanish-speaking Mexico) and gorge in the northeast (which is closer to French Canada), with the rest of the country graduating between these two according to geography. In Canada, a gorge is usually narrow while a ravine is more open and often wooded. The military-derived word defile is occasionally used in the United Kingdom.pronounced
Most canyons were formed by a process of long-time erosion from a plateau or table-land 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 than in wet areas because physical weathering has a more localized effect in arid zones. The wind and water from the river combine to erode and cut away less resistant materials such as shales. The freezing and expansion of water also serve to help form canyons. Water seeps into cracks between the rocks and freezes, pushing the rocks apart and eventually causing large chunks to break off the canyon walls, in a process known as frost wedging.Canyon walls are often formed of resistant sandstones or granite.
Sometimes large rivers run through canyons as the result of gradual geological uplift. These are called entrenched rivers, because they are unable to easily alter their course. In the United States, the Colorado River in the Southwest and the Snake River in the Northwest are two examples of tectonic uplift.
Canyons often form in areas of limestone rock. As limestone is soluble to a certain extent, cave systems form in the rock. When a cave system collapses, a canyon is left, as in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire, England.
A box canyon is a small canyon that is generally shorter and narrower than a river canyon, with steep walls on three sides, allowing access and egress only through the mouth of the canyon. Box canyons were frequently used in the western United States as convenient corrals, with their entrances fenced.
The definition of "largest canyon" is imprecise, because a canyon can be large by its depth, its length, or the total area of the canyon system. Also, the inaccessibility of the major canyons in the Himalaya contributes to them 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 Grand Canyon (or Tsangpo Canyon), along the Yarlung Tsangpo River in Tibet, is regarded by some as the deepest canyon in the world at 5,500 metres (18,000 ft). It is slightly longer than the Grand Canyon in the United States. Others consider the Kali Gandaki Gorge in midwest Nepal to be the deepest canyon, with a 6,400 metres (21,000 ft) difference between the level of the river and the peaks surrounding it.
Vying for the deepest canyon in the Americas is the Cotahuasi Canyon and Colca Canyon, in southern Peru. Both have been measured at over 3,500 metres (11,500 ft) deep.
The Grand Canyon of northern Arizona in the United States, with an average depth of 1,600 metres (5,200 ft) and a volume of 4.17 trillion cubic metres (147 trillion cubic feet), is one of the world's largest canyons. It was among the 28 finalists of the New7Wonders of Nature worldwide poll. (Some referred to it as one of the seven natural wonders of the world.)
The largest canyon in Africa is the Fish River Canyon in Namibia.
In August 2013, the discovery of Greenland's Grand Canyon was reported, based on the analysis of data from Operation IceBridge. It is located under an ice sheet. At 750 kilometres (470 mi) long, it is believed to be the longest canyon in the world.
The Capertee Valley in Australia is commonly reported as being the second largest (in terms of width) canyon in the world.
Some canyons have notable cultural significance. Evidence of early humanoids has been discovered in Africa's Olduvai Gorge. In the southwestern United States, canyons are important archeologically because of the many cliff-dwellings built in such areas, largely by the ancient Pueblo people who were their first inhabitants.
The following list contains only the most notable canyons of the world, arranged by continent and then country.
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.
A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over a very long period of time. Some valleys are formed through erosion by glacial ice. These glaciers may remain present in valleys in high mountain or polar areas. At lower latitudes and altitudes, these glacially formed valleys may have been created or enlarged during ice ages but now are ice-free and occupied by streams or rivers. In desert areas, valleys may be entirely dry or carry a watercourse only rarely. In areas of limestone bedrock, dry valleys may also result from drainage taking place underground rather than at the surface. Rift valleys arise principally from earth movements, rather than erosion. Many different types of valley are described by geographers, using terms that may be global in use or else applied only locally.
The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile.
The Intermontane Plateaus of the Western United States is one of eight U.S. Physiographic regions (divisions) of the physical geography of the contiguous United States. The region is composed of intermontane plateaus and mountain ranges. It is subdivided into physiographic provinces, which are each subdivided into physiographic sections.
The Colorado Plateau, also known as the Colorado Plateau Province, is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the southwestern United States. This province covers an area of 336,700 km2 (130,000 mi2) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.
The Yarlung Tsangpo Grand Canyon, also known as the Yarlung Zangbo Grand Canyon, the Tsangpo Canyon, the Brahmaputra Canyon or the Tsangpo Gorge, is a canyon along the Yarlung Tsangpo River in Tibet Autonomous Region, China. It is the deepest canyon in the world, and at 504.6 kilometres (313.5 mi) is slightly longer than the Grand Canyon in the United States, making it one of the world's largest. The Yarlung Tsangpo originates near Mount Kailash and runs east for about 1,700 kilometres (1,100 mi), draining a northern section of the Himalayas before it enters the gorge just downstream of Pei, Tibet, near the settlement of Zhibe. The canyon has a length of about 240 kilometres (150 mi) as the gorge bends around Mount Namcha Barwa and cuts its way through the eastern Himalayan range. Its waters drop from about 2,900 metres (9,500 ft) near Pei to about 1,500 metres (4,900 ft) at the end of the Upper Gorge where the Po Tsangpo River enters. The river continues through the Lower Gorge to the Indian border at an elevation of 660 metres (2,170 ft). The river then enters Arunachal Pradesh and eventually becomes the Brahmaputra.
The Kali Gandaki Gorge or Andha Galchi is the gorge of the Kali Gandaki in the Himalayas in Nepal. By some definitions, it may be one of the deepest gorges in the world.
The Yarlung Tsangpo, also called Yarlung Zangbo is the upper stream of the Brahmaputra River located in the Tibet Autonomous Region, China. It is the longest river of Tibet.
The Canyon Lands Section of the Colorado Plateau is a physiographic section of the larger Colorado Plateaus province, which in turn is part of the larger Intermontane Plateaus physiographic division in the Western United States
The Colorado River is a major river of the western United States and northwest Mexico in North America. Its headwaters are in the Rocky Mountains where La Poudre Pass Lake is its source. Located in north central Colorado it flows southwest through the Colorado Plateau country of western Colorado, southeastern Utah and northwestern Arizona where it flows through the Grand Canyon. It turns south near Las Vegas, Nevada, forming the Arizona–Nevada border in Lake Mead and the Arizona–California border a few miles below Davis Dam between Laughlin, Nevada and Needles, California before entering Mexico in the Colorado Desert. Most of its waters are diverted into the Imperial Valley of Southern California. In Mexico its course forms the boundary between Sonora and Baja California before entering the Gulf of California. This article describes most of the major features along the river.
The Tonto Group is a name for an assemblage of related sedimentary strata, collectively known by geologists as a Group, that comprises the basal sequence Paleozoic strata exposed in the sides of the Grand Canyon. As currently defined, the Tonto groups consists of the Sixtymile Formation, Tapeats Sandstone, Bright Angel Shale, Muav Limestone, and Frenchman Mountain Dolostone. Historically, it included only the Tapeats Sandstone, Bright Angel Shale, and Muav Limestone. Because these units are defined by lithology and three of them interfinger and intergrade laterally, they lack the simple layer cake geology as they are typically portrayed as having and geological mapping of them is complicated.
The Cambrian Tapeats Sandstone is the lower geologic unit, about 230 feet (70 m) thick, at its maximum, of the 3-member Tonto Group. It is famous for being the highly-resistant mostly-horizontal unit above the 1,000 my, Great Unconformity expressed areally in the Grand Canyon of Arizona; also in other areas of Arizona and adjacent Nevada.
The Middle Permian Toroweap Formation is a thin, darker geologic unit, between the brighter colored units of the Kaibab Limestone above, and Coconino Sandstone below. It is a prominent unit in Grand Canyon, Arizona, USA, found through sections of the South Rim, Grand Canyon, and the North Rim, of the Kaibab Plateau; also the Kaibab's southeast extension to Cape Royal, the Walhalla Plateau. The Colorado River of the Grand Canyon makes its excursion from due-south to due-west around the Walhalla Plateau, as it enters the east end of the Grand Canyon's interior, Granite Gorge. The formation is also found in southeast Utah.
The Toroweap Fault of northwest Arizona and southwest Utah is part of a fault system of the west Grand Canyon region, Arizona, USA; also the west perimeter regions of the Coconino and Colorado Plateaus. The Hurricane Fault originates at the Toroweap Fault, in the region of the Colorado River, and strikes as the westerly depression of the Toroweap Fault. The Toroweap strikes northerly from the Colorado at the east of Toroweap Valley, and enters south Utah; from the Colorado River, the Hurricane Fault strikes north-northwest along the west flank of the small, regional Uinkaret Mountains, the west border of Toroweap Valley. The Hurricane Fault, and the Hurricane Cliffs strike into southwest Utah as part of the west, and southwest perimeter of the Colorado Plateau. The Hurricane Cliffs are made of Kaibab Limestone, an erosion resistant, cliff-forming rock unit.
Isis Temple is a prominence in the Grand Canyon, Arizona, USA. It is located below the North Rim and adjacent to Granite Gorge. The prominence lies north of the north bank of the west-flowing Colorado River and is just north of Granite Gorge. The Trinity Creek and canyon flow due south at its west border; its north, and northeast border/flank is formed by Phantom Creek and canyon, a west tributary of Bright Angel Creek; the creeks intersect about 3 mi (4.8 km) southeast, and 1.0 mi (1.6 km) north of Granite Gorge. The Isis Temple prominence, is only about 202 ft (62 m) lower than Grand Canyon Village, the main public center on Grand Canyon’s South Rim.
The Peacock Mountains are a small, 26 mi (42 km) long mountain range in northwest Arizona, US. The range is a narrow sub-range, and an extension north, at the northeast of the Hualapai Mountains massif, which lies to the southwest. The range is defined by the Hualapai Valley to the northwest, and north and south-flowing washes on its east border, associated with faults and cliffs; the Cottonwood Cliffs are due east, and are connected to the Aquarius Cliffs southward at the west perimeter of the Aquarius Mountains; the cliffs are a result of the Aquarius Fault, which is an extension southward from the Grand Wash Cliffs and Grand Wash Fault which crosses the Colorado River at Lake Mead, and the west perimeter of the Grand Canyon/Colorado Plateau.
The Shinarump Conglomerate is a geologic formation found in the Four Corners region of the United States. It was deposited in the early Triassic period.
The Vishnu Basement Rocks is the name recommended for all Early Proterozoic crystalline rocks exposed in the Grand Canyon region. They form the crystalline basement rocks that underlie the Bass Limestone of the Unkar Group of the Grand Canyon Supergroup and the Tapeats Sandstone of the Tonto Group. These basement rocks have also been called either the Vishnu Complex or Vishnu Metamorphic Complex. These Early Proterozoic crystalline rocks consist of metamorphic rocks that are collectively known as the Granite Gorge Metamorphic Suite; sections of the Vishnu Basement Rocks contain Early Paleoproterozoic granite, granitic pegmatite, aplite, and granodiorite that have intruded these metamorphic rocks, and also, intrusive Early Paleoproterozoic ultramafic rocks.
The Bailey–Morshead exploration of the Tsangpo Gorge was an unauthorised expedition by Frederick Bailey and Henry Morshead in 1913 which for the first time established the definite route by which the Tsangpo River reaches the sea from north of Himalaya, through the Tsangpo Gorge.
|Look up canyon in Wiktionary, the free dictionary.|
Media related to Canyons at Wikimedia Commons