A ribbon lake is a long and deep, finger-shaped

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

, usually found in a

glacial trough U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight s ...

. As such, a ribbon lake is one of a number of glacial landscapes, including

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 frequen ...

corries The Corries were a Scottish folk group that emerged from the Scottish folk revival of the early 1960s. The group was a trio from their formation until 1966 when founder Bill Smith left the band but Roy Williamson and Ronnie Browne continued ...

, rock lips, rock basins and terminal moraines. Such a lake's formation begins when a

glacier A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its Ablation#Glaciology, ablation over many years, often Century, centuries. It acquires dis ...

moves over an area containing alternate bands of hard and soft

bedrock In geology, bedrock is solid Rock (geology), rock that lies under loose material (regolith) within the crust (geology), crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface mater ...

. The sharp-edged

boulder In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In c ...

s that are picked up by the glacier and carried at the bottom of the glacier erode the softer rock more quickly by abrasion, thus creating a hollow called a rock basin. On either side of the rock basin, the more resistant rock is eroded less and these outcrops of harder rock are known as rock bars, which act as dams between which rainwater may accumulate after the retreat of the

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages and gree ...

, filling up the rock basin and creating a ribbon lake. A ribbon lake may also form behind a terminal or recessional

moraine A moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice shee ...

, both of which also act as dams, enabling water to accumulate behind them. A ribbon lake may also occur if a tributary glacier joins a main glacier. The increase in power can create a trough, which is filled with water from a river/meltwater to create a ribbon lake. Examples of ribbon lakes include

Windermere Windermere (sometimes tautology (language), tautologically called Windermere Lake to distinguish it from the nearby town of Windermere, Cumbria (town), Windermere) is the largest natural lake in England. More than 11 miles (18 km) in leng ...

, the largest natural lake in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

;

Panguipulli Lake The Panguipulli Lake ( ; es, Lago Panguipulli) is one of the " Seven Lakes" in Panguipulli municipality, southern Chile. The lake is of glacial origin and it is enclosed by mountain ranges of the Andes, on all sides except the west, where the to ...

, in southern

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

;

Lake Washington Lake Washington is a large freshwater lake adjacent to the city of Seattle. It is the largest lake in King County and the second largest natural lake in the state of Washington, after Lake Chelan. It borders the cities of Seattle on the west, ...

, in the state of

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

; and

Llyn Ogwen Llyn Ogwen (; ) is a ribbon lake in north-west Wales. It lies alongside the A5 road between two mountain ranges of Snowdonia, the Carneddau and the Glyderau. Somewhat unusually, the county boundary at this point is drawn so that the lake itsel ...

, in northwestern

Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...

References

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Online at Google Books
Glacial erosion landforms Lakes by type {{geo-term-stub