Proglacial lake

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A proglacial lake is impounded by the terminal moraine of the retreating Schoolroom Glacier in Grand Teton National Park, Wyoming, USA.

In geology, a proglacial lake is a lake formed either by the damming action of a moraine or ice dam during the retreat of a melting glacier, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age approximately 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere.

Proglacial Lakes of the North American Great Lakes (USGS 1915)

In some cases, such lakes gradually evaporated during the warming period after the Quaternary ice age. In other cases, such as Glacial Lake Missoula and Glacial Lake Wisconsin in the United States, the sudden rupturing of the supporting dam caused glacial lake outburst floods, the rapid and catastrophic release of dammed water resulting in the formation of gorges and other structures downstream from the former lake. Good examples of these structures can be found in the Channeled Scablands of eastern Washington, an area heavily eroded by the Missoula Floods.[1]

In Great Britain, Lake Lapworth, Lake Harrison and Lake Pickering were examples of proglacial lakes. Ironbridge Gorge in Shropshire and Hubbard's Hills in Lincolnshire are examples of a glacial overspill channel created when the water of a proglacial lake rose high enough to breach the lowest point in the containing watershed.

The receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are. Several such lakes have formed rapidly during the 20th century. These lakes may burst, creating a hazard for zones below. Many natural dams (usually moraines) containing the lake water have been reinforced with safety dams. Some 34 such dams have been built in the Cordillera Blanca to contain proglacial lakes.

Several proglacial lakes have also formed in recent decades at the end of glaciers on the eastern side of New Zealand's Southern Alps. The most accessible, Lake Tasman, hosts boat trips for tourists.

Ice Dammed Lakes[edit]

Flood/River[2] Location Date Peak discharge(106 m3/s) Reference
Kuray Altai, Russia Late Pleistocene 18 Baker et al., 1993
Missoula Northwestern USA Late Pleistocene 17 O'Connor and Baker, 1992
Darkhat Lakes Mongolia Late Pleistocene 4 Rudoy, 1998
Jassater Lakes Altai, Russia Late Pleistocene 2 Rudoy, 1998
Yaloman Lakes Altai, Russia Late Pleistocene 2 Rudoy, 1998
Ulymon Lakes Altai, Russia Late Pleistocene 1.9 Rudoy, 1998
Lake Regina Canada/USA Late Pleistocene 0.8 Lord and Kehew, 1987
Wabash River Indiana, USA Late Pleistocene 0.27 Vaughn and Ash, 1983
Lake Agassiz Canada/USA Late Pleistocene 0.13 Matsch, 1983
Porcupine River Alaska, USA Late Pleistocene 0.13 Thorson, 1989
Russell Fiord Alaska, USA 1986 0.10 Mayo, 1989

See also[edit]

References[edit]

  1. ^ http://www.cr.nps.gov/history/online_books/geology/publications/inf/72-2/sec5.htm USGS The Channeled Scablands of Eastern Washington
  2. ^ O’Connor, J.E., and Costa, J.E., 2004, The world’s largest floods, past and present—Their causes and magnitudes: U.S. Geological Survey Circular 1254, 13 p.

Bibliography[edit]

  • Baker, V.R., Benito, G., and Rudoy, A.N., 1993. Paleo-hydrology of late Pleistocene superflooding, Altay Mountains, Siberia: Science, 259, p. 348–350.
  • Lord, M.L., and Kehew, A.E., 1987, Sedimentology and paleohydrology of glacial-lake outburst deposits in southeastern Saskatchewan and northwestern North Dakota: Geological Society of America Bulletin v. 99, p. 663–673.
  • Matsch, C.L., 1983, River Warren, the southern outlet of Glacial Lake Agassiz, in Teller, J.T., and Lee, Clayton, Glacial Lake Agassiz: Geological Association of Canada Special Paper 26, p. 231–244.
  • Mayo, L.R., 1989, Advance of Hubbard Glacier and 1986 outburst of Russell Fiord, Alaska, U.S.A.: Annals of Glaciology, v. 13, p. 189–194.
  • O'Connor, J.E., and Baker, V.R., 1992, Magnitudes and implications of peak discharges from Glacial Lake Missoula: Geological Society of America Bulletin, v. 104, p. 267–279.
  • Rudoy, A., 1998, Mountain ice-dammed lakes of southern Siberia and their influence on the development and regime of the intracontinental runoff systems of North Asia in the late Pleistocene, in Benito, G., Baker, V.R., and Gregory, K.J., eds., Paleohydrology and Environmental Change: John Wiley and Sons, p. 215–234.
  • Thorson, R.M., 1989, Late Quaternary paleofloods along the Porcupine River, Alaska—Implication for regional correlation, in Carter, L.D., Hamilton, T.D., and Galloway, J.P., eds., Late Cenozoic history of the interior basins of Alaska and the Yukon: U.S. Geological Survey Circular 1026, p. 51–54.
  • Vaughn, D., and Ash, D.W., 1983, Paleohydrology and geomorphology of selected reaches of the upper Wabash River, Indiana: Geological Society of America Program with Abstracts, v. 15, no. 6, p. 711.