Pyramidal peak

A pyramidal peak, sometimes called a glacial horn in extreme cases, is an angular, sharply pointed mountain peak which results from the cirque erosion due to multiple glaciers diverging from a central point. Pyramidal peaks are often examples of nunataks.

Matterhorn from Domhütte - 2
The Matterhorn, a classic example of a pyramidal peak.

Formation

Cirques mountainmass en
Cross-section of cirque erosion over time

Glaciers, typically forming in drainages on the sides of a mountain, develop bowl-shaped basins called cirques (sometimes called ‘corries’ - from Scottish Gaelic coire [kʰəɾə] (a bowl) - or cwms). Cirque glaciers have rotational sliding that abrades the floor of the basin more than walls and that causes the bowl shape to form. As cirques are formed by glaciation in an alpine environment, the headwall and ridges between parallel glaciers called arêtes become more steep and defined. This occurs due to freeze/thaw and mass wasting beneath the ice surface. It is widely held that a common cause for headwall steepening and extension headward is the crevasses known as bergschrund that occur between the moving ice and the headwall. Plucking and shattering can be seen here by those exploring the crevasses. A cirque is exposed when the glacier that created it recedes.

When three or more of these cirques converge on a central point, they create a pyramid-shaped peak with steep walls. These horns are a common shape for mountain tops in highly glaciated areas. The number of faces of a horn depends on the number of cirques involved in the formation of the peak: three to four is most common. Horns with more than four faces include the Weissmies and the Mönch.[1] A peak with four symmetrical faces is called a Matterhorn (after The Matterhorn).[2]

The peak of a glacial horn will often outlast the arêtes on its flanks.[1] As the rock around it erodes, the horn gains in prominence. Eventually, a glacial horn will have near vertical faces on all sides. In the Alps, "horn" is also the name of very exposed peaks with slope inclinations of 45-60° (e.g. Kitzbüheler Horn).

Examples

Zabeshkoto ezero pirin IMG 7410
Muratov peak, Pirin Mountain, Bulgaria
Konceto and Vichren
Kutelo and Vihren viewed from Koncheto, Pirin Mountain, Bulgaria

See also

References

  1. ^ a b Embleton, Clifford; King, Cuchlaine A. (1968). Glacial and Periglacial Geomorphology. New York: St. Martin's Press. p. 193. LCCN 68-20348.
  2. ^ "Glossary of Glacier Terminology". US Geological Survey. Retrieved 12 October 2012.

Bibliography

  • Easterbrook, Don J. (1999). Surface Processes and Landforms (2nd ed.). Upper Saddle River, NJ: Prentice Hall. pp. 334–336. ISBN 978-0138609580.

External links

Alpspitze

The Alpspitze is a mountain, 2,628 m, in Bavaria, Germany. Its pyramidal peak is the symbol of Garmisch-Partenkirchen and is one of the best known and most attractive mountains of the Northern Limestone Alps. It is made predominantly of Wetterstein limestone from the Upper Triassic.

Arête

An arête is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequently this results in a saddle-shaped pass, called a col. The edge is then sharpened by freeze-thaw weathering, and the slope on either side of the arete steepened through mass wasting events and the erosion of exposed, unstable rock. The word ‘arête’ is actually French for edge or ridge; similar features in the Alps are described with the German equivalent term Grat.

Where three or more cirques meet, a pyramidal peak is created.

Cockburn Island (Antarctica)

Cockburn Island is an oval island 2.7 kilometres (1.7 mi) long, consisting of a high plateau with steep slopes surmounted on the northwest side by a pyramidal peak 450 m (1,476 ft) high, lying in the north-east entrance to Admiralty Sound, south of the north-east end of the Antarctic Peninsula. It was discovered by a British expedition (1839-43) led by Captain James Clark Ross, who named it for Admiral Sir George Cockburn, then serving as First Naval Lord (commander-in-chief of the Royal Navy).

Corner Peak

Corner Peak (63°35′S 58°39′W) is a pyramidal peak, 930 metres (3,050 ft) high, with considerable rock exposed on its northern face. Located in the northeastern Srednogorie Heights, 8 nautical miles (15 km) east-southeast of Cape Roquemaurel, it marks a corner in the broad glacial valley of Malorad Glacier which rises immediately to the southeast and fans out northwest to form a piedmont ice sheet on the northwest side of the Trinity Peninsula. It was named by the Falkland Islands Dependencies Survey following a 1946 survey.

Doumer Island

Doumer Island is an island 8.3 km (4.5 nmi) long and 3.7 km (2 nmi) wide, surmounted by a snow-covered pyramidal peak, 515 m (1,690 ft), lying between the south portions of Anvers Island and Wiencke Island in the Palmer Archipelago of Antarctica. It was first seen by the Belgian Antarctic Expedition, 1897–99, under Adrien de Gerlache. It was resighted and charted by the French Antarctic Expedition, 1903–05, under Jean-Baptiste Charcot, who named it for Paul Doumer, President of the French Chamber of Deputies and later President of France.

Garnet Peak

Garnet Peak is a mountain in east-central British Columbia, Canada, located between Goat Creek and Azure Lake. Situated in the Cariboo Mountains of the Columbia Mountains, it is the third highest mountain in Wells Gray Provincial Park with an elevation of 2,876 m (9,436 ft). Garnet Peak is a prominent mountain as one drives the Clearwater Valley Road into Wells Gray Park and is first visible from 80 km (50 mi) south at the Clearwater Valley Overlook.Garnet Peak stands alone as a pyramidal peak. From Clearwater Lake, it appears to be part of the Huntley-Buchanan Ridge which extends most of the length of Azure Lake on its north side. It is actually located about 3 km (1.9 mi) north of Tryfan Mountain and the two are connected by a broad hogsback at an elevation of 2,400 m (7,874 ft). This fact becomes obvious as one travels north on Clearwater Lake by boat; Garnet Peak actually gets smaller and eventually disappears behind the Huntley-Buchanan Ridge. Garnet Peak is not visible from anywhere on Azure Lake.

Holst Peak

Holst Peak (71°20′S 70°6′W) is a rocky pyramidal peak, rising to about 1,000 metres (3,300 ft), midway between the south end of the Walton Mountains and the LeMay Range in the central part of Alexander Island, Antarctica. It was first mapped by D. Searle of the Falkland Islands Dependencies Survey in 1960 from air photos obtained by the Ronne Antarctic Research Expedition, 1947–48, and was named by the UK Antarctic Place-Names Committee for Gustav Holst, the English composer.

Hvannadalshnúkur

Hvannadalshnúkur or Hvannadalshnjúkur (pronounced [ˈkvanːatalsˌn̥juːkʏr]) is a pyramidal peak on the northwestern rim of the summit crater of the Öræfajökull volcano in Iceland and is the highest in Iceland.

MacKay Peak

MacKay Peak is an ice-covered pyramidal peak rising to 770 m in Friesland Ridge, Tangra Mountains, Livingston Island in the South Shetland Islands, Antarctica. It is linked by Pleven Saddle to Tervel Peak to the east-northeast, and surmounts Peshtera Glacier to the north and Charity Glacier to the south.

The peak is named after Captain Donald MacKay, Master of the American shallop Sarah who, while seal hunting in the islands in 1820-21, sent home a collection of minerals and rocks to the New York Lyceum of Natural History, forerunner of the American Museum of Natural History.

May Peak

May Peak (85°57′S 132°23′W) is a pyramidal peak rising to over 2,200 metres (7,200 ft) at the west side of Reedy Glacier, standing 1 nautical mile (2 km) west of Stich Peak in the Quartz Hills of Marie Byrd Land. It was mapped by the United States Geological Survey from surveys and U.S. Navy air photos, 1960–64, and was named by the Advisory Committee on Antarctic Names for Lieutenant Commander Robert L. May, a U.S. Navy helicopter pilot at McMurdo Station, 1962–63.

Monte Sarmiento

Monte Sarmiento is a pyramidal peak with a glaciated saddle-shaped summit located within Alberto de Agostini National Park, in the Chilean portion of Tierra del Fuego. It rises abruptly from the east shore of the Magdalena Channel and marks the western border of the Cordillera Darwin. The mountain is frequently shrouded in clouds, but when it is visible is "the most sublime spectacle in Tierra del Fuego" according to the words of

Charles Darwin, one of the many people who have been captivated by the beauty of this mountain.

Mount Assiniboine

Mount Assiniboine, also known as Assiniboine Mountain, is a pyramidal peak mountain located on the Great Divide, on the British Columbia/Alberta border in Canada.

At 3,618 m (11,870 ft), it is the highest peak in the Southern Continental Ranges of the Canadian Rockies. Mt. Assiniboine rises nearly 1,525 m (5,003 ft) above Lake Magog. Because of its resemblance to the Matterhorn in the Alps, it is nicknamed the "Matterhorn of the Rockies".Mt. Assiniboine was named by George M. Dawson in 1885. When Dawson saw Mt. Assiniboine from Copper Mountain, he saw a plume of clouds trailing away from the top. This reminded him of the plumes of smoke emanating from the teepees of Assiniboine Indians.Mt. Assiniboine lies on the border between Mount Assiniboine Provincial Park, in British Columbia, and Banff National Park, in Alberta. The park does not have any roads and thus can only be reached by a six-hour hike or horse-pack 27 km (17 mi), three-hour bike ride (now disallowed to reduce human / grizzly encounters) or helicopter. The usual approach is via Bryant Creek. From Canmore follow the Smith-Dorien road to the Mount Shark parking lot. The trail is well signed. A helipad is also here.

Mount Bradley

Mount Bradley (63°53′S 58°37′W) is a pyramidal peak, 835 metres (2,740 ft) high, at the southeast end of a ridge descending from Detroit Plateau, surmounting Znepole Ice Piedmont to the east and Dreatin Glacier to the southwest. The peak is 4 nautical miles (7 km) southwest of Mount Reece in the southern Trinity Peninsula. It was charted in 1945 by the Falkland Islands Dependencies Survey, who named it for K.G. Bradley, Colonial Secretary in the Falkland Islands at the time.

Mount Douglas (Antarctica)

Mount Douglas (76°31′S 161°18′E) is a striking pyramidal peak, 1,750 m, near the head of Fry Glacier, on the divide between the Fry and the Mawson Glaciers. The New Zealand Northern Survey Party of the Commonwealth Trans-Antarctic Expedition (1956–58) established a survey station on its summit in December 1957 which was named for Murray H. Douglas, a member of the party.

Mount McKenzie (Antarctica)

Mount McKenzie is a pyramidal peak, 2,255 metres (7,400 ft) high, situated 3.5 nautical miles (6 km) southeast of Saxton Ridge in the Amery Peaks of the Aramis Range, Prince Charles Mountains, Antarctica. It was seen by the Australian National Antarctic Research Expeditions southern party led by W.G. Bewsher, 1956–57, and was named by the Antarctic Names Committee of Australia for John A. McKenzie, a cook at Mawson Station in 1956.

Norton Couloir

The Norton Couloir or Great Couloir is a steep gorge high on the north face of Mount Everest in Tibet which lies east of the pyramidal peak and extends to within 150 m below the summit.

Its companion to the west of the summit is the Hornbein Couloir.

Scarlatti Peak

Scarlatti Peak (71°16′S 70°26′W) is a conspicuous pyramidal peak, rising to 750 m, 8 nautical miles (15 km) northwest of Holst Peak and 12 nautical miles (22 km) east of Walton Mountains in the central part of Alexander Island, Antarctica. The peak was first mapped from air photos obtained by the Ronne Antarctic Research Expedition in 1947–48, by Searle of the Falkland Islands Dependencies Survey in 1960. Named by the United Kingdom Antarctic Place-Names Committee for Alessandro Scarlatti (1660–1725), Italian composer.

Summit

A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. The topographic terms acme, apex, peak (mountain peak), and zenith are synonymous.

The term top (mountain top) is generally used only for a mountain peak that is located at some distance from the nearest point of higher elevation. For example, a big massive rock then to the main summit of a mountain is not considered a summit. Summits near a higher peak, with some prominence or isolation, but not reaching a certain cutoff value for the quantities, are often considered subsummits (or subpeaks) of the higher peak, and are considered part of the same mountain. A pyramidal peak is an exaggerated form produced by ice erosion of a mountain top. Summit may also refer to the highest point along a line, trail, or route.

The highest summit in the world is Everest with height of 8844.43 m above sea level (29,029 ft). The first official ascent was made by Tenzing Norgay and Sir Edmund Hillary. They reached the mountain's peak in 1953.Whether a highest point is classified as a summit, a sub peak or a separate mountain is subjective. The UIAA definition of a peak is that it has a prominence of 30 metres (98 ft) or more; it is a mountain summit if it has a prominence of at least 300 metres (980 ft). Otherwise, it's a subpeak.

In many parts of the western United States, the term summit refers to the highest point along a road, highway, or railroad. For example, the highest point along Interstate 80 in California is referred to as Donner Summit and the highest point on Interstate 5 is Siskiyou Mountain Summit.

Two Prudential Plaza

Two Prudential Plaza is a 64-story skyscraper located in the Loop area of Chicago, Illinois, United States. At 995 feet (303 m) tall, it is currently the sixth-tallest building in Chicago and the seventeenth-tallest in the U.S., being only five feet from 1,000 feet, making it the closest of any building under 1,000. Built in 1990, the building was designed by the firm Loebl Schlossman & Hackl, with Stephen T. Wright as the principal in charge of design. It has been honored with 8 awards, including winning the Best Structure Award from the Structural Engineers Association of Illinois in 1995.At the time of completion, Two Prudential was the world's tallest reinforced concrete building. Its distinctive shape features stacked chevron setbacks on the north and south sides, a pyramidal peak rotated 45°, and an 80-foot (24 m) spire.

The building is attached to One Prudential Plaza (formerly known as the Prudential Building). Without its spire, the building's height is still slightly greater than that of One Prudential Plaza's pinnacle.In May 2006, BentleyForbes, a Los Angeles-based real estate investment firm, run by Frederick Wehba and his family purchased Two Prudential Plaza, along with its sister property, One Prudential Plaza for $470 million.In 2015, BentleyForbes defaulted on the mortgage for the towers due to the Great Recession and New York-based investors 601W Companies and Berkley Properties took control of the property after investing more than $100 million in equity to recapitalize. BentleyForbes, the prior controlling owner of the towers, continues to have an interest in the owning partnership.The building is also the new home of the Chicago Tribune and tronc, Inc. after leaving Tribune Tower in July 2018.

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