Glacial landforms are

landform 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, ...

s created by the action of

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 over many years, often centuries. It acquires distinguishing features, such a ...

s. Most of today's glacial landforms were created by the movement of large

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...

s during the

Quaternary glaciation The Quaternary glaciation, also known as the Pleistocene glaciation, is an alternating series of glacial and interglacial periods during the Quaternary period that began 2.58 Ma (million years ago) and is ongoing. Although geologists describ ...

s. Some areas, like

Fennoscandia __NOTOC__ Fennoscandia ( Finnish, Swedish and no, Fennoskandia, nocat=1; russian: Фенноскандия, Fennoskandiya) or the Fennoscandian Peninsula is the geographical peninsula in Europe, which includes the Scandinavian and Kola penin ...

and the southern

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, have extensive occurrences of glacial landforms; other areas, such as the

Sahara , photo = Sahara real color.jpg , photo_caption = The Sahara taken by Apollo 17 astronauts, 1972 , map = , map_image = , location = , country = , country1 = , ...

, display rare and very old fossil glacial landforms.

Erosional landforms

As the glaciers expand, due to their accumulating weight of

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughou ...

and ice they crush and abrade and scour surfaces such as rocks and

bedrock In geology, bedrock is solid rock that lies under loose material ( regolith) within the crust of Earth or another terrestrial planet. Definition Bedrock is the solid rock that underlies looser surface material. An exposed portion of be ...

. The resulting erosional landforms include

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 ...

cirque A (; from the Latin word ') is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic , meaning a pot or cauldron) and (; ). A cirque may also be a similarly shaped landf ...

s, glacial horns,

arête An arête ( ) is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequ ...

s, trim lines, U-shaped valleys, roches moutonnées,

overdeepening Overdeepening is a characteristic of basins and valleys eroded by glaciers. An overdeepened valley profile is often eroded to depths which are hundreds of metres below the deepest continuous line (the thalweg) along a valley or watercourse. This p ...

s and

hanging valley A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams over ...

s. * Cirque: Starting location for mountain glaciers * Cirque stairway: a sequence of cirques * U-shaped, or trough, valley: U-shaped valleys are created by mountain glaciers. When filled with ocean water so as to create an

inlet An inlet is a (usually long and narrow) indentation of a shoreline, such as a small arm, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In marine ...

, these valleys are called

fjord In physical geography, a fjord or fiord () is a long, narrow inlet with steep sides or cliffs, created by a glacier. Fjords exist on the coasts of Alaska, Antarctica, British Columbia, Chile, Denmark, Germany, Greenland, the Faroe Islands, Icel ...

s. *

Arête An arête ( ) is a narrow ridge of rock which separates two valleys. It is typically formed when two glaciers erode parallel U-shaped valleys. Arêtes can also form when two glacial cirques erode headwards towards one another, although frequ ...

: spiky high land between two glaciers, if the glacial action erodes through, a ''spillway'' (or

col In geomorphology, a col is the lowest point on a mountain ridge between two peaks.Whittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984, p. 103. . It may also be called a gap. Particularly rugged and forbidding co ...

) forms * Valley step: an abrupt change in the longitudinal slope of a glacial valley

Depositional landforms

Later, when the glaciers retreated leaving behind their freight of crushed rock and sand (

glacial drift In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater. Drift is often subdivided into (unsorted and) unstratified drift (gla ...

), they created characteristic depositional landforms. Examples include glacial

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 ...

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 Ame ...

s, and

kame A kame, or ''knob'', is a glacial landform, an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the ...

Drumlin A drumlin, from the 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 glacial ice acting on underlying unconsolidated ...

s and ribbed moraines are also landforms left behind by retreating glaciers. Many depositional landforms result from sediment deposited or reshaped by meltwater and are referred to as fluvioglacial landforms. The stone walls of

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...

contain many

glacial erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundred ...

s, rocks that were dragged by a glacier many miles from their bedrock origin. *

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 Ame ...

: Built up bed of a subglacial stream. *

Kame A kame, or ''knob'', is a glacial landform, an irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depression on a retreating glacier, and is then deposited on the land surface with further melting of the ...

: Irregularly shaped mound. *

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 ...

: Feature can be terminal (at the end of a glacier), lateral (along the sides of a glacier), or medial (formed by the merger of lateral moraines from contributary glaciers). *

Outwash fan An outwash fan is a fan-shaped body of sediments deposited by braided streams from a melting glacier. Sediment locked within the ice of the glacier gets transported by the streams of meltwater, and deposits on the outwash plain, at the terminus o ...

: Braided stream flowing from the front end of a glacier.

Glacial lakes and ponds

Lakes and ponds may also be caused by glacial movement.

Kettle lake A kettle (also known as a kettle lake, kettle hole, or pothole) is a depression/hole in an outwash plain formed by retreating glaciers or draining floodwaters. The kettles are formed as a result of blocks of dead ice left behind by retreating g ...

s form when a retreating glacier leaves behind an underground or surface chunk of ice that later melts to form a depression containing water.

Moraine-dammed lake A moraine-dammed lake occurs when the terminal moraine has prevented some meltwater from leaving the valley. Its most common shape is that of a long ribbon (ribbon lake). Example of moraine dammed lakes include: *Argentina/Chile: General Carre ...

s occur when glacial debris dam a stream (or snow runoff). Jackson Lake and

Jenny Lake Jenny Lake is located in Grand Teton National Park in the U.S. state of Wyoming. The lake was formed approximately 12,000 years ago by glaciers pushing rock debris which carved Cascade Canyon during the last glacial maximum, forming a terminal m ...

Grand Teton National Park Grand Teton National Park is an American national park in northwestern Wyoming. At approximately , the park includes the major peaks of the Teton Range as well as most of the northern sections of the valley known as Jackson Hole. Grand Teton ...

are examples of moraine-dammed lakes, though Jackson Lake is enhanced by a man-made dam. *

: Depression, formed by a block of ice separated from the main glacier, in which the lake forms * Tarn: A lake formed in a

* Paternoster lake: A series of lakes in a glacial valley, formed when a stream is dammed by successive recessional moraines left by an advancing or retreating glacier *

Glacial lake A glacial lake is a body of water with origins from glacier 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, roughly 10, ...

: A lake that formed between the front of a glacier and the last recessional moraine

Ice features

Apart from the landforms left behind by glaciers, glaciers themselves may be striking features of the terrain, particularly in the

polar regions of Earth The polar regions, also called the frigid zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitudes are dominated by float ...

. Notable examples include

valley glacier A valley is an elongated low area often running between hills or mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers or streams ...

s where glacial flow is restricted by the valley walls,

crevasse A crevasse is a deep crack, that forms in a glacier or ice sheet that can be a few inches across to over 40 feet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid p ...

s in the upper section of glacial ice, and

icefall An icefall is a portion of certain glaciers characterized by relatively rapid flow and chaotic crevassed surface, caused in part by gravity. The term ''icefall'' is formed by analogy with the word ''waterfall'', which is a similar phenomenon of ...

s—the ice equivalent of

waterfall A waterfall is a point in a river or stream where water flows over a vertical drop or a series of steep drops. Waterfalls also occur where meltwater drops over the edge of a tabular iceberg or ice shelf. Waterfalls can be formed in several ...

Disputed origin

The glacial origin of some landforms has been questioned. Erling Lindström has advanced the thesis that roches moutonnées may not be entirely glacial landforms taking most of their shape before glaciation. Jointing that contribute to the shape typically predate glaciation and roche moutonnée-like forms can be found in tropical areas such as

East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territories make up Eastern Africa: Due to the historica ...

and

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

. Further at

Ivö Lake Ivö Lake ( Swedish: ''Ivösjön'') is the largest and deepest lake of Skåne, Sweden, located in the municipalities of Kristianstad and Bromölla in the northeastern part of Skåne County. It covers an area of just under , with a maximum depth of ...

in Sweden weathered rock surfaces exposed by

kaolin Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedra ...

mining resemble roche moutonnée. The idea of elevated flat surfaces being shaped by glaciation—the

glacial buzzsaw The glacial buzzsaw is a hypothesis claiming erosion by warm-based glaciers is key to limit the height of mountains above certain threshold altitude. To this the hypothesis adds that great mountain massifs are leveled towards the equilibrium line ...

effect—has been rejected by various scholars. In the case of Norway the elevated paleic surface has been proposed to have been shaped by the glacial buzzsaw effect. However, this proposal is difficult to reconcile with the fact that the paleic surface consist of a series of steps at different levels. Further glacial

s, that in the buzzsaw hypothesis contribute to belevel the landscape, are not associated to any paleosurface levels of the composite paleic surface, nor does the modern

equilibrium line altitude Glaciology (; ) is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, clima ...

(ELA) or the

Last Glacial Maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eu ...

ELA match any given level of the paleic surface. The elevated plains of West Greenland are also unrelated to any glacial buzzsaw effect. The

Gulf of Bothnia The Gulf of Bothnia (; fi, Pohjanlahti; sv, Bottniska viken) is divided into the Bothnian Bay and Bothnian Sea, and it is the northernmost arm of the Baltic Sea, between Finland's west coast ( East Bothnia) and the Sweden's east coast ( We ...

and

Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...

, two large depressions at the centre of former

s, are known to be more the result of

tectonics Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents k ...

than of any weak glacial erosion.

References

External links

Illustrated glossary of alpine glacial landforms

*Diagram illustrating mechanisms of glacial landforms i
''The Ice Melts: Deposition''
on page 6 of "Pennsylvania and the Ice Age" published 1999 by PA DCN
Bureau of Topographic and Geologic Survey
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