A glacial lake is a body of water with origins from

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

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 word ("little 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 glacial ice acting on underlying unconsolidated till or ground ...

hills A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as mountains. Hills fall und ...

. As the ice age ended, these melted to create lakes. These lakes are often surrounded by

, along with other evidence of the glacier such as moraines,

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 Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

al features such as striations and chatter marks. These lakes are clearly visible in aerial photos of

landforms A landform is a land feature on the solid surface of the Earth or other planetary body. They may be natural or may be anthropogenic (caused or influenced by human activity). Landforms together make up a given terrain, and their arrangement i ...

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 g ...

. 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. Mat ...

, Earth has lost more than 50% of its glaciers. This along with the current increase in retreating glaciers caused by

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

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 j� ...

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 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 in which 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, ...

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 six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would ...

s and

boron Boron is a chemical element; it has 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 three ...

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. Glacial lake sediments also archive changes in geochemistry and pollen records as a result of climate change and human activities. During the transition from the Last Glacial Period to the Holocene climatic optimum, soil development was enhanced, whereas early human activities such as deforestation have resulted in elevated soil erosion. These events can be reflected in geochemistry and isotope signatures in the lake sediments.

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 (; translates to "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 r ...

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 ...

s and arctic skua. 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 Jökulsárlón 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, making it one of the largest travel destinations in Patagonia.

Gallery

File:Pirin ezera IMG 3836.jpg, One of the Valyavishki Lakes and Gazey Summit,

Pirin The Pirin Mountains ( ) are a mountain range in southwestern Bulgaria, with the highest peak, Vihren, at an altitude of . The range extends about from the north-west to the south-east and is about wide, spanning a territory of . To the north ...

Mountain,

Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...

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

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. "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 i ...

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

Maritsa Maritsa or Maritza ( ), also known as Evros ( ) and Meriç ( ), is a river that runs through the Balkans in Southeast Europe. With a length of ,

river, seen from

Musala Musala ( ); from Arabic through Ottoman Turkish: from '' Musalla'', "near God" or "place for prayer" is the highest peak in the Rila Mountains, as well as in Bulgaria and the entire Balkan Peninsula, standing at . With a topographic prominence ...

, Rila Mountain,

File:Sentiero del Viandante DSC 6340 (14020554463).jpg, View of

Lake Como Lake Como ( , ) also known as Lario, is a lake of glacial origin in Lombardy, Italy. It has an area of , making it the third-largest lake in Italy, after Lake Garda and Lake Maggiore. At over deep, it is one of the deepest lakes in Europe. ...

Lombardy The Lombardy Region (; ) is an administrative regions of Italy, region of Italy that covers ; it is located in northern Italy and has a population of about 10 million people, constituting more than one-sixth of Italy's population. Lombardy is ...

, Northern

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, a glacial lake in the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

File:GLMsed.jpg, Laminated

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

from Glacial Lake Missoula,

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

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

Kaghan Valley The Kaghan Valley (Hindko, ) is an Alpine climate, alpine valley in Mansehra District of Khyber Pakhtunkhwa, Pakistan. The valley stretches across the northern Pakistan, rising from its lowest elevation of to its highest point at the Babusar P ...

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

File:Katora lake dir.jpg, Katora Lake in

Kumrat Valley Kumrat () is an alpine valley of the Dir Kohistan region in the Upper Dir District, Khyber Pakhtunkhwa province of Pakistan. There is around 45 minutes drive to Kumrat Valley from the town of Thal on the banks of the Panjkora River. It is among th ...

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 Neelam Valley, 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. Geography and locat ...

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:Lacul_Bucura,_Lacul_Ana_a_Lacul_Bucurelu.jpg, Glacier cirque lake Bucura, the largest glacier lake in

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

. File:Tasman Glacier LC0251.jpg, Tasman Lake, New Zealand File:Lake Kaniere.jpg, Lake Kaniere in the West Coast region of

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

File:Gopło_-_panorama.JPG, Lake Gopło in the

Kuyavia Kuyavia (; ), also referred to as Cuyavia, is a historical region in north-central Poland, situated on the left bank of Vistula, as well as east from Noteć River and Lake Gopło. It is divided into three traditional parts: north-western (with th ...

region of

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...

, view from the mouse tower

References

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