A moraine-dammed lake occurs when the

terminal moraine A terminal moraine, also called end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge ...

has prevented some

meltwater Meltwater is water released by the melting of snow or ice, including glacial ice, tabular icebergs and ice shelves over oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reducing. Meltwater ca ...

from leaving the valley. Its most common shape is that of a long ribbon (

ribbon lake A ribbon lake is a long and deep, finger-shaped lake, usually found in a glacial trough. As such, a ribbon lake is one of a number of glacial landscapes, including arêtes, corries, rock lips, rock basins and terminal moraines. Such a lake's ...

). Example of moraine dammed lakes include: *Argentina/Chile: General Carrera/Buenos Aires Lake *Chile: Calafquén Lake,

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 ...

*Ireland:

Lough Dan Lough Dan ( ga, Loch Deán) is a scenic boomerang-shaped ribbon lake largely set on private property, in the Wicklow Mountains in Ireland. Lough Dan lake lies at the base of Luggala and Knocknacloghoge mountains. The lough is fed by the Clo ...

*Nepal:

Tsho Rolpa Tsho Rolpa (also ''Cho Rolpa'') is one of the biggest glacial lakes in Nepal. The lake, which is located at an altitude of in the Rolwaling Valley, Dolakha District, has grown considerably over the last 50 years due to glacial melting in the Him ...

*New Zealand: Lake Hāwea, Lake Ohau,

Lake Pukaki Lake Pukaki is the largest of three roughly parallel alpine lakes running north–south along the northern edge of the Mackenzie Basin on New Zealand's South Island. The others are Lakes Tekapo and Ohau. All three lakes were formed when the te ...

Lake Tekapo __NOTOC__ Lake Tekapo ( mi, Takapō) is the second-largest of three roughly parallel lakes running north–south along the northern edge of the Mackenzie Basin in the South Island of New Zealand (the others are Lake Pukaki and Lake Ohau). ...

Lake Wakatipu Lake Wakatipu ( mi, Whakatipu Waimāori) is an inland lake ( finger lake) in the South Island of New Zealand. It is in the southwest corner of the Otago region, near its boundary with Southland. ''Lake Wakatipu'' comes from the original Māori n ...

, and

Lake Wanaka 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 larger ...

(i.e., almost all large lakes in the

South Island The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...

) *Switzerland:

Lake Zurich __NOTOC__ Lake Zurich ( Swiss German/ Alemannic: ''Zürisee''; German: ''Zürichsee''; rm, Lai da Turitg) is a lake in Switzerland, extending southeast of the city of Zürich. Depending on the context, Lake Zurich or ''Zürichsee'' can be used t ...

*United States: Donner Lake in

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

Flathead Lake Flathead Lake ( fla, člq̓etkʷ, label= Salish, kut, yawuʔnik̓ ʔa·kuq̓nuk) is a large natural lake in northwest Montana. The lake is a remnant of the ancient, massive glacial dammed lake, Lake Missoula of the era of the last interglacia ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

Mille Lacs Lake Mille Lacs Lake (also called Lake Mille Lacs or Mille Lacs) is a large but shallow lake in the U.S. state of Minnesota. It is located in the counties of Mille Lacs, Aitkin, and Crow Wing, roughly 75 miles north of the Minneapolis-St. Paul m ...

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over t ...

Wallowa Lake Wallowa Lake is a ribbon lake south of Joseph, Oregon, United States, at an elevation of . Impounded by high moraines, it was formed by a series of Pleistocene glaciers. On the south end of the lake is a small community made up of vacation homes ...

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

*Wales:

Llyn Peris Llyn Peris is a lake in Snowdonia, Wales, approximately 1.8 km long and situated close to the villages of Llanberis and Nant Peris, and the smaller twin of Llyn Padarn. The lake was formed glacially and is an example of a moraine-dammed lak ...

and its twin

Llyn Padarn Llyn Padarn is a glacially formed lake in Snowdonia, Gwynedd, north Wales, and is an example of a moraine dammed lake. The lake is approximately long (about 240 acres) and at its deepest point is deep, and is one of the largest natural lakes ...

. *Poland:

Morskie Oko Morskie Oko, or Eye of the Sea in English, is the largest and fourth-deepest lake in the Tatra Mountains, in southern Poland. It is located deep within the Tatra National Park in the Rybi Potok (the Fish Brook) Valley, of the High Tatras mountai ...

Zakopane Zakopane ( Podhale Goral: ''Zokopane'') is a town in the extreme south of Poland, in the southern part of the Podhale region at the foot of the Tatra Mountains. From 1975 to 1998, it was part of Nowy Sącz Voivodeship; since 1999, it has been ...

*Slovakia: Strbske pleso,

Velke Hincovo pleso The Master Genealogist (TMG) is genealogy software originally created by Bob Velke for Microsoft DOS in 1993, with a version for Microsoft Windows released in 1996. Data entry was customized through the use of user-defined events, names, and rel ...

In the 19th century the Argentine explorer Francisco Perito Moreno suggested that many Patagonian lakes draining to the Pacific were in fact part of the Atlantic basin but had been

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 sh ...

dammed during the

quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million year ...

glaciation A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate bet ...

s changing their outlets to the west. He argued that as originally belonging to the Atlantic basin these lakes should be awarded to Argentina. Most of the lakes situated in the Himalaya of Nepal and Bhutan are also of the moraine dammed type. They may burst at any time. That is why the areas below such lakes have high risk of flooding.

See also