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Cirque (landform)
Encyclopedia
Scottish Gaelic language
Scottish Gaelic is a Celtic language native to Scotland. A member of the Goidelic branch of the Celtic languages, Scottish Gaelic, like Modern Irish and Manx, developed out of Middle Irish, and thus descends ultimately from Primitive Irish....
coire meaning a pot or cauldron
Cauldron
A cauldron or caldron is a large metal pot for cooking and/or boiling over an open fire, with a large mouth and frequently with an arc-shaped hanger.- Etymology :...
) is an amphitheatre
Amphitheatre
An amphitheatre is an open-air venue used for entertainment and performances.There are two similar, but distinct, types of structure for which the word "amphitheatre" is used: Ancient Roman amphitheatres were large central performance spaces surrounded by ascending seating, and were commonly used...
-like valley
Valley
In geology, a valley or dale is a depression with predominant extent in one direction. A very deep river valley may be called a canyon or gorge.The terms U-shaped and V-shaped are descriptive terms of geography to characterize the form of valleys...
head, formed at the head of a valley glacier by erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
. The concave amphitheatre shape is open on the downhill side corresponding to the flatter area of the stage,
while the cupped seating section is generally steep cliff-like slopes down which ice and glaciated debris combine and converge from the three or more higher sides. The floor of the cirque ends up bowl shaped as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens, hence experiences somewhat greater erosion forces, and is most often scooped out somewhat below the level of cirque's low-side outlet (stage) and its down slope (backstage) valley. If the cirque is subject to seasonal melting, the floor of the cirque most often forms a tarn
Tarn (lake)
A tarn is a mountain lake or pool, formed in a cirque excavated by a glacier. A moraine may form a natural dam below a tarn. A corrie may be called a cirque.The word is derived from the Old Norse word tjörn meaning pond...
(small lake) behind the moraine
Moraine
A moraine is any glacially formed accumulation of unconsolidated glacial debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past glacial maximum. This debris may have been plucked off a valley floor as a glacier advanced or it may have...
and glacial till damming the outlet.
Formation
Cliff
In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually...
s. The highest cliff often is called a headwall
Headwall
In physical geography and geology the headwall of a glacial cirque is its highest cliff.In civil engineering, a headwall is a small retaining wall placed at the outlet of a stormwater pipe or culvert....
. The fourth side is the lip, threshold or sill, the side at which the glacier flowed away from the cirque. Many glacial cirques contain tarns
Tarn (lake)
A tarn is a mountain lake or pool, formed in a cirque excavated by a glacier. A moraine may form a natural dam below a tarn. A corrie may be called a cirque.The word is derived from the Old Norse word tjörn meaning pond...
dammed by either till (debris) or a bedrock threshold. When enough snow accumulates it can flow out the opening of the bowl and form valley glaciers which may be several kilometers long.
Cirques form in conditions which are favorable; in the northern hemisphere the conditions include the north-east slope where they are protected from the majority of the sun’s energy and from the prevailing winds. These areas are sheltered from heat, encouraging the accumulation of snow; if the accumulation of snow increases, the snow turns into glacial ice. The process of nivation
Nivation
Nivation is a collective name for the different processes that occur under a snow patch. The primary processes are mass wasting and the freeze and thaw cycle, in which fallen snow gets compacted into firn or névé...
follows, whereby a hollow in a slope may be enlarged by freeze-thaw weathering and glacial erosion. The freeze-thaw cycle erodes at the lower rocks and causes it to disintegrate, which may result in an avalanche bringing down more snow and rock to add to the growing glacier. Eventually, this hollow may become large enough that glacial erosion intensifies. The enlarging of this open ended concavity creates a larger leeward deposition zone, furthering the process of glaciation. Debris (or till) in the ice also may abrade (glacial abrasion
Abrasion (geology)
Abrasion is the mechanical scraping of a rock surface by friction between rocks and moving particles during their transport by wind, glacier, waves, gravity, running water or erosion. After friction, the moving particles dislodge loose and weak debris from the side of the rock...
) the bed surface; should ice move down a slope it would have a ‘sandpaper effect’ on the bedrock
Bedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
beneath, on which it scrapes.
Bowl (vessel)
A bowl is a common open-top container used in many cultures to serve food, and is also used for drinking and storing other items. They are typically small and shallow, although some, such as punch bowls and salad bowls, are larger and often intended to serve many people.Bowls have existed for...
shape in the side of the mountain, with the headwall being weathered by constant freezing and thawing, and as well as being eroded by plucking
Plucking (glaciation)
Glacial plucking exploits pre-existing fractures in the bedrock. This plays a key role in opening and creating new fractures but has only provided small segments of loose material. This is then followed by the entrainment of the loosened rock by the ice. During the process of entrainment, loose...
. The basin will become deeper if it continues to become eroded by abrasion. Should plucking and abrasion continue, the dimensions of the cirque will increase, but the proportion of the landform would remain roughly the same. A bergschrund
Bergschrund
A bergschrund is a crevasse that forms where the moving glacier ice separates from the stagnant ice above. It is often a serious obstacle for mountaineers, who sometimes abbreviate "bergschrund" to "schrund"....
forms when the movement of the glacier separates the moving ice from the stationary ice forming a crevasse. The method of erosion of the headwall lying between the surface of the glacier and the cirque’s floor has been attributed to freeze-thaw mechanisms. The temperature within the bergschrund changes very little, however, studies have shown that frost shattering may happen with only small changes in temperature. Water that flows into the bergschrund can be cooled to freezing temperatures by the surrounding ice allowing freeze-thaw mechanisms to occur.
Arete
Areté is the term meaning "virtue" or "excellence", from Greek ἈρετήArete may also be used:*as a given name of persons or things:**Queen Arete , a character in Homer's Odyssey.***197 Arete, an asteroid....
, or steep sided ridge, forms. When three or more cirques erode toward one another, a pyramidal peak
Pyramidal peak
A pyramidal peak, or sometimes in its most extreme form called a glacial horn, is a mountaintop that has been modified by the action of ice during glaciation and frost weathering...
is created. In some cases, this peak will be made accessible by one or more arêtes. The Matterhorn
Matterhorn
The Matterhorn , Monte Cervino or Mont Cervin , is a mountain in the Pennine Alps on the border between Switzerland and Italy. Its summit is 4,478 metres high, making it one of the highest peaks in the Alps. The four steep faces, rising above the surrounding glaciers, face the four compass points...
in the European Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
is an example of such a peak.
As glaciers can only originate above the snowline, studying the location of present day cirques provides information on past glaciations patterns and climate change.
Notable cirques
- Australia
- Blue Lake CirqueBlue Lake (New South Wales)The Blue Lake is one of only four cirque lakes found in mainland Australia, the other three, Cootapatamba, Albina, and Club are shallower than BL and are held...
, New South WalesNew South WalesNew South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
- Blue Lake Cirque
- Asia
- Chandra TaalChandra TaalChandra Taal , or Chandra Tal, is situated at an altitude of about in the Himalayas. Mountains of scree overlook the lake on one side, and a magnificent cirque presents a view on the other. The name of the lake originates from its crescent shape...
, Himachal PradeshHimachal PradeshHimachal Pradesh is a state in Northern India. It is spread over , and is bordered by the Indian states of Jammu and Kashmir on the north, Punjab on the west and south-west, Haryana and Uttar Pradesh on the south, Uttarakhand on the south-east and by the Tibet Autonomous Region on the east...
, IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world... - Cirque Valley, Hindu KushHindu KushThe Hindu Kush is an mountain range that stretches between central Afghanistan and northern Pakistan. The highest point in the Hindu Kush is Tirich Mir in the Chitral region of Khyber-Pakhtunkhwa, Pakistan.It is the westernmost extension of the Pamir Mountains, the Karakoram Range, and is a...
, PakistanPakistanPakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan... - Western CwmWestern CwmOften called the Valley of Silence, the Western Cwm is a broad, flat, gently undulating glacial valley basin terminating at the foot of the Lhotse Face of Mount Everest. It was named by George Leigh Mallory when he first saw it in 1921...
, Khumbu Himal, NepalNepalNepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
- Chandra Taal
- Europe
- Circo de GredosCirco de GredosThe Circo de Gredos is a glacial cirque situated in the central part of the northern slope of the Sierra de Gredos...
, Sierra de GredosSierra de GredosThe Sierra de Gredos is a mountain range in the centre of the Iberian Peninsula, located between Ávila, Cáceres, Madrid and Toledo. It has been declared a regional park. Its highest point is Pico Almanzor, at 2,592 metres....
, SpainSpainSpain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula... - Cirque de GavarnieCirque de GavarnieThe Cirque de Gavarnie is a cirque in the central Pyrenees, in the Pyrenees National Park. The cirque is 800m wide and about 3000m wide at the top.Major features of the cirque are La Brèche de Roland and the Gavarnie Falls....
, PyreneesPyreneesThe Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...
, FranceFranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France... - Cirque d'EstaubéCirque d'EstaubéThe Cirque d'Estaubé is a cirque in the central Pyrenees in the Pyrenees National Park, forming the frontier between France and Spain. The cirque lies 4 km to the east of its better known neighbour, the Cirque de Gavarnie, which is accessible via the Hourquette d'Alans ; the Marboré valley is...
, PyreneesPyreneesThe Pyrenees is a range of mountains in southwest Europe that forms a natural border between France and Spain...
, FranceFranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France... - Cirque du Fer à Cheval, Savoy Alps, FranceFranceThe French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
- Coire an t-SneachdaCoire an t-SneachdaCoire an t-Sneachda is a glacial cirque or corrie landform in the Cairngorm or Am Monadh Ruadh mountain range in the Grampian Mountains of the Scottish Highlands....
, Grampian Mountains in the Scottish HighlandsScottish HighlandsThe Highlands is an historic region of Scotland. The area is sometimes referred to as the "Scottish Highlands". It was culturally distinguishable from the Lowlands from the later Middle Ages into the modern period, when Lowland Scots replaced Scottish Gaelic throughout most of the Lowlands... - Śnieżne KotłyŚnieżne KotłyŚnieżne Kotły are two glacial cirques in the western Krkonoše mountains , situated in the Karkonosze National Park on the Polish side of the border. They are a unique example of the alpine landscape in the area and have been a nature reserve since 1933.- Description :The walls of both cirques are...
, KarkonoszeKarkonoszeKrkonoše is a mountain range located in the north of the Czech Republic and the south-west of Poland, part of the Sudetes mountain system . The Czech-Polish border, which divides the historic regions of Bohemia and Silesia, runs along the main ridge...
, PolandPolandPoland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
- Circo de Gredos
- North America
- Cirque of the TowersCirque of the TowersThe Cirque of the Towers is located in the Wind River Range Wyoming, U.S., part of which is in the Bridger Wilderness in Bridger-Teton National Forest, while the remainder is in the Popo Agie Wilderness in Shoshone National Forest. Located in the southern section of the Wind River Range , the...
, WyomingWyomingWyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Iceberg CirqueIceberg CirqueThe Iceberg Cirque is a large cirque that has been carved out by glaciation. It is located in Glacier National Park in the U.S. state of Montana. It is near Iceberg Lake in the Many Glacier section of the park, and can be approached by a hike starting at the Many Glacier Hotel....
, MontanaMontanaMontana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Summit LakeSummit Lake ParkSummit Lake Park is a park located along Mount Evans Scenic Byway about 38 miles west of Denver, Colorado. The park is 160 acres in size and contains alpine tundra. Land to the east of the lake is in a state of permafrost which helps to prevent drainage of the area...
cirque, and others on Mount EvansMount EvansMount Evans is a mountain in the Front Range region of the Rocky Mountains, in Clear Creek County, Colorado. It is one of 54 fourteeners in Colorado, and the closest fourteener to Denver...
, ColoradoColoradoColorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Great Basin and others on Mount KatahdinMount KatahdinMount Katahdin is the highest mountain in Maine at . Named Katahdin by the Penobscot Indians, the term means "The Greatest Mountain". Katahdin is the centerpiece of Baxter State Park: a steep, tall mountain formed from underground magma. The flora and fauna on the mountain are typical of those...
, MaineMaineMaine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Great GulfGreat GulfThe Great Gulf is a glacial cirque, or amphitheater-like valley head formed from a glacier by erosion, located in the White Mountains of New Hampshire...
, New HampshireNew HampshireNew Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district... - Tuckerman RavineTuckerman RavineTuckerman Ravine is a glacial cirque sloping eastward on the southeast face of Mt. Washington, in the White Mountains of New Hampshire. Although it draws hikers throughout the year, and skiers throughout the winter, it is best known for the many "spring skiers" who ascend it on foot and ski down...
, New HampshireNew HampshireNew Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
, United StatesUnited StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
- Cirque of the Towers