Tarn (lake)

Glacial action forming a tarn

Robert Tarn, Mackenzie Tarn and Johnston Tarn (foreground to background), Tarn Shelf, Mt Field National Park, Tasmania, Australia. The tarns were formed by glacial scouring.

A tarn (or corrie loch) is a mountain lake or pool, formed in a cirque excavated by a glacier. It is formed when either rain or river water fills the cirque. 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. Its more specific use as a mountain lake emerges as it is the commonly used term for all ponds in the upland areas of Northern England. Here, it retains a broader use, referring to any small lake or pond, regardless of its location and origin.

In Scandinavian languages a tjern or tjärn, tärn or tjørn is a small natural lake, often in a forest or with vegetation close around it or growing into the lake.

Gallery

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  Upper Thornton Lake in North Cascades National Park, USA

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  View of Andrews Tarn at the base of Andrews Glacier in Rocky Mountain National Park, USA

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  Štrbské pleso, the most famous tarn in Slovakia, High Tatras mountain

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  Veľké Hincovo pleso tarn, the biggest and deepest tarn in Slovakia

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  Pacific Tarn in the Tenmile Range near Breckenridge, Colorado; this is the highest lake in the United States at 13,420 feet.

Lousy Lake (tarn) in base of Luna Cirque, North Cascades Nat. Park, Pickett Range, North Cascades, WA. Photo taken Aug. 2011

Lousy Lake (tarn) in N. Cascades National Park, Pickett Range, WA. Photo taken August 2011

See also

• Pond