A glacial lake is a body of water with origins from

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 ...

activity. They are formed when a glacier erodes the land and then melts, filling the depression created by the glacier.

Formation

Near the end of the last

glacial period 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 betw ...

, roughly 10,000 years ago, glaciers began to retreat. A retreating glacier often left behind large deposits of ice in hollows between

drumlins A drumlin, from the Irish Gaelic, Irish word ''droimnín'' ("littlest ridge"), first recorded in 1833, in the classical sense is an elongated hill in the shape of an inverted spoon or half-buried egg formed by glacier, glacial ice acting on und ...

hills A hill is a landform that extends above the surrounding terrain. It often has a distinct summit. Terminology The distinction between a hill and a mountain is unclear and largely subjective, but a hill is universally considered to be not as ...

. As the ice age ended, these melted to create lakes. This is apparent in the

Lake District The Lake District, also known as the Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous for its lakes, forests, and mountains (or ''fells''), and its associations with William Wordswor ...

in Northwestern

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 ...

where post-glacial sediments are normally between 4 and 6 metres deep. These lakes are often surrounded by

, along with other evidence of the glacier such as

moraines 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 she ...

esker An esker, eskar, eschar, or os, sometimes called an ''asar'', ''osar'', or ''serpent kame'', is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North Amer ...

s and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

al features such as

striations Striations means a series of ridges, furrows or linear marks, and is used in several ways: * Glacial striation * Striation (fatigue), in material * Striation (geology), a ''striation'' as a result of a geological fault * Striation Valley, in ...

and

chatter mark A chatter mark is one or, more commonly, a series of wedge shaped marks left by chipping of a bedrock surface by rock fragments carried in the base of a glacier (glacial plucking). Marks tend to be crescent-shaped and oriented at right angles ...

s. These lakes are clearly visible in aerial photos of

landforms A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, m ...

in regions that were glaciated during the last

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 ...

. The formation and characteristics of glacial lakes vary between location and can be classified into glacial erosion lake, ice-blocked lake, moraine-dammed lake, other glacial lake, supraglacial lake, and subglacial lake.

Glacial lakes and changing climate

Since the glaciation of the

Little Ice Age The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Ma ...

, Earth has lost more than 50% of its glaciers. This along with the current increase in retreating glaciers caused by climate change has created a shift from frozen to liquid water, increasing the extent and volume of glacial lakes around the world. Most glacial lakes present today can be found in Asia, Europe, and North America. The area which will see the greatest increase in lake formation is the Southern Tibetan Plateau region from debris covered glaciers. This increase in glacial lake formation also indicates an increase in occurrence of

glacial lake outburst flood A glacial lake outburst flood (GLOF) is a type of outburst flood caused by the failure of a dam containing a glacial lake. An event similar to a GLOF, where a body of water contained by a glacier melts or overflows the glacier, is called a jö ...

events caused by damming and subsequent breaking of moraine and ice.

Sediments

The amount of sediment found in glacial lakes varies, and has a general stratigraphic sequence of organic muds, glacial clays, silty clays, and sands based on time of formation. Over time the glacial lake sediments are subjected to change. As seen in the

English Lake District The Lake District, also known as the Lakes or Lakeland, is a mountainous region in North West England. A popular holiday destination, it is famous for its lakes, forests, and mountains (or ''fells''), and its associations with William Wordswor ...

, the layers of the sediments at the bottom of the lakes contain evidence of the rate of erosion. The elemental make up of the sediments are not associated with the lakes themselves, but by the migration of the elements within the soil, such as iron and manganese. The distribution of these elements, within the lake bed, are attributed to the condition of the

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, t ...

and the chemical composition of the water. Sediment deposition can also be influenced by animal activity; including the distribution of biochemical elements, which are elements that are found in organic organisms, such as phosphorus and sulfur. The amount of

halogen The halogens () are a group in the periodic table consisting of five or six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). In the modern IUPAC nomenclature, this group is ...

s and

boron Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...

found in the sediments accompanies a change in erosional activity. The rate of deposition reflects the amount of halogen and boron in the deposited sediments. The scouring action of the glaciers pulverizes minerals in the rock over which the glacier passes. These pulverized minerals become sediment at the bottom of the lake, and some of the

rock flour Rock flour, or glacial flour, consists of fine-grained, silt-sized particles of rock, generated by mechanical grinding of bedrock by glacial erosion or by artificial grinding to a similar size. Because the material is very small, it becomes suspe ...

becomes suspended in the water column. These suspended minerals support a large population of algae, making the water appear green.

Biotic ecosystem

Biodiversity and productivity tend to be lower in glacial lakes as only cold-tolerant and cold-adapted species can withstand their harsh conditions. Glacial rock flour and low nutrient levels create an oligotrophic environment where few species of plankton, fish and benthic organisms reside. Before becoming a lake the first stages of glacial recession melt enough freshwater to form a shallow lagoon. In the case of Iceland's

Jökulsárlón Jökulsárlón (; literally "glacial river lagoon") is a large glacial lake in southern part of Vatnajökull National Park, Iceland. Situated at the head of the Breiðamerkurjökull glacier, it developed into a lake after the glacier started rece ...

glacial lagoon located on the edge of the Atlantic Ocean, tides bring in an array of fish species to the edge of the glacier. These fish attract an abundance of predators from birds to marine mammals, that are searching for food. These predators include fauna such as, seals,

arctic tern The Arctic tern (''Sterna paradisaea'') is a tern in the family Laridae. This bird has a circumpolar breeding distribution covering the Arctic and sub-Arctic regions of Europe (as far south as Brittany), Asia, and North America (as far south a ...

s and

arctic skua The parasitic jaeger (''Stercorarius parasiticus''), also known as the Arctic skua, Arctic jaeger or parasitic skua, is a seabird in the skua family Stercorariidae. It is a migratory species that breeds in Northern Scandinavia, Scotland, Iceland ...

. Glacial lakes that have been formed for a long period of time have a more diverse ecosystem of fauna originating form neighboring tributaries or other glacial refugia. For example, many native species of the great lakes basin entered via the Mississippi basin refugia within the past 14,000 years.

Societal perspectives

Glacial lakes act as fresh water storage for the replenishing of a region's water supply and serve as potential electricity producers from hydropower. Glacial lakes' aesthetic nature can also stimulate economic activity through the attraction of the tourism industry. Thousands of tourists visit the

glacial lagoon in Iceland annually to take part in commercial boat tours and every two to four years thousands visit the Argentino glacial lake in Argentina to witness the collapse of the cyclically formed arch of ice from the

Perito Moreno glacier The Perito Moreno Glacier () is a glacier located in Los Glaciares National Park in southwest Santa Cruz Province, Argentina. It is one of the most important tourist attractions in the Argentine Patagonia. The ice formation, in length, is one ...

, making it one of the largest travel destinations in Patagonia.

Gallery

File:Pirin ezera IMG 3836.jpg, One of the

Valyavishki Lakes The Valyavishki Lakes () is a group of lakes in the northern part of the Pirin National Park in southwestern Bulgaria and includes 10 lakes. They are situated in the cirque of the same name. The lakes are glacial and lie on a granite bed. They a ...

and

Gazey Gazey () is a peak in the Pirin mountain, Bulgaria situated on a small sideward ridge of the Polejansli Ridge. It is 2,761 m high, which makes it ninth in the mountain. Viewed from Polejan it looks small, rising slightly above the Upper Polejan la ...

Summit,

Pirin , photo=Pirin-mountains-Bansko.jpg , photo_caption=Pirin scenery in winter , country= Bulgaria, , parent= , geology= granite, gneiss, marble, limestone , area_km2=2585 , range_coordinates = , length_km=80 , length_orientation= north-s ...

Mountain,

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

File:Ibón de Sabocos (14562086186).jpg, Ibón de Sabocos, in the

Tena Valley The Tena Valley is a valley located at the southern side of the Pyrenees, in the Alto Gállego comarca, province of Huesca, and is crossed by the Gállego river from north to south. Its main town is Sallent de Gállego. The valley is surrounded ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

. "Ibón" is the local word in Aragonese for glacial lakes. File:Jokulsarlon lake, Iceland.jpg,

, a glacial lake in Iceland. To the right, the mouth of the glacier

Vatnajökull Vatnajökull ( Icelandic pronunciation: , literally "Glacier of Lakes"; sometimes translated as Vatna Glacier in English) is the largest and most voluminous ice cap in Iceland, and the second largest in area in Europe after the Severny Island ice ...

. File:Maritsaorigin2.JPG, The glacial lakes, that give origin to the

Maritsa Maritsa or Maritza ( bg, Марица ), also known as Meriç ( tr, Meriç ) and Evros ( ell, Έβρος ), is a river that runs through the Balkans in Southeast Europe. With a length of ,Musala Musala ( bg, Мусала ); from Arabic language, Arabic through Ottoman Turkish language, Ottoman Turkish: from ''Musalla'', "near God" or "place for prayer" is the highest mountain, peak in the Rila, Rila Mountains, as well as in Bulgaria and ...

Rila Mountain Rila ( bg, Рила, ) is the highest mountain range of Bulgaria, the Balkan Peninsula and Southeast Europe. It is situated in southwestern Bulgaria and forms part of the Rila– Rhodope Massif. The highest summit is Musala at an elevation of 2,92 ...

File:GLMsed.jpg, Laminated

claystone Mudrocks are a class of fine-grained siliciclastic sedimentary rocks. The varying types of mudrocks include siltstone, claystone, mudstone, slate, and shale. Most of the particles of which the stone is composed are less than and are too sm ...

from

Glacial Lake Missoula Lake Missoula was a prehistoric proglacial lake in western Montana that existed periodically at the end of the last ice age between 15,000 and 13,000 years ago. The lake measured about and contained about of water, half the volume of Lake Mic ...

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 Columbi ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

File:Saif ul Malook Lake - KPK Pakistan 4.jpg, Saif-ul-Malook Lake in

Kaghan Valley The Kaghan Valley ( ur, ) is an alpine valley located in the Mansehra District of Khyber Pakhtunkhwa, Pakistan. The valley covers a distance of across northern Pakistan, rising from its lowest elevation of to its highest point at the Babusar ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

File:Katora lake dir.jpg,

Katora Lake Katora Lake is an alpine glacial lake located in the upper reaches of Jahaz Banda, Kumrat valley in Upper Dir District of Khyber Pakhtunkhwa the Province of Pakistan. The lake is fed by the surrounding melting glacier waters. The word Katora means ...

Kumrat Valley Kumrat ( ur, ) is a valley in the Upper Dir District of Khyber Pakhtunkhwa province of Pakistan. Kumrat Valley is located about 45 minutes away from the town of Thal on the banks of the Panjkora River, and is among the most popular tourist spots i ...

File:Dudipatsar Lake.jpg, Dudipatsar Lake in

File:Ratti Gali Lake .jpg,

Ratti Gali Lake Ratti Gali Lake is an alpine glacial lake which is located in Neelum Valley, Azad Kashmir, Pakistan . The lake is located at an altitude of . The lake is fed by the surrounding glacier waters of the mountains. See also * Chitta Katha Lake *Sa ...

in Neelum Valley,

File:Пирин, Самодивски езера.jpg, One of the

Samodivski Lakes The Samodivski Lakes () is a small group of lakes in Pirin, southwestern Bulgaria, part of the larger group of Popovski lakes. They are situated very close to each other in a small cirque to the south west of the Popovo Lake between the peak Dzheng ...

Mountain,

File:Tasman Glacier LC0251.jpg,

Tasman Lake Tasman Lake is a proglacial lake formed by the recent retreat of the Tasman Glacier in New Zealand's South Island. In the early 1970s, there were several small meltwater ponds on the Tasman Glacier. By 1990, these ponds had merged into Tasman L ...

, New Zealand File:Lake Kaniere.jpg,

Lake Kaniere Lake Kaniere is a glacial lake located on the West Coast of New Zealand's South Island, nearly 200 m deep and surrounded on three sides by mountains and mature rimu forest. It is regarded by many as the most beautiful of the West Coast lakes, and ...

in the

West Coast West Coast or west coast may refer to: Geography Australia * Western Australia *Regions of South Australia#Weather forecasting, West Coast of South Australia * West Coast, Tasmania **West Coast Range, mountain range in the region Canada * Britis ...

region of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

References

{{commons category, Glacial lakes Lakes by type Glacial landforms