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Glaciology (; ) is the scientific study 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 as ...
s, or more generally
ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaqu ...
and natural phenomena that involve ice. Glaciology is an interdisciplinary Earth science that integrates
geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...
,
geology Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ea ...
,
physical geography Physical geography (also known as physiography) is one of the three main branches of geography. Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as the atmosphere, ...
, geomorphology,
climatology Climatology (from Greek , ''klima'', "place, zone"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study ...
,
meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...
,
hydrology Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...
,
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
, and
ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
. The impact of glaciers on people includes the fields of
human geography Human geography or anthropogeography is the branch of geography that studies spatial relationships between human communities, cultures, economies, and their interactions with the environment. It analyzes spatial interdependencies between social i ...
and
anthropology Anthropology is the scientific study of humanity, concerned with human behavior, human biology, cultures, societies, and linguistics, in both the present and past, including past human species. Social anthropology studies patterns of be ...
. The discoveries of water ice on the
Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...
,
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...
, Europa and
Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest ...
add an extraterrestrial component to the field, which is referred to as "astroglaciology".


Overview

A glacier is an extended mass of ice formed from snow falling and accumulating over a long period of time; glaciers move very slowly, either descending from high mountains, as in valley glaciers, or moving outward from centers of accumulation, as in
continental glacier 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. Areas of study within glaciology include glacial history and the reconstruction of past glaciation. A glaciologist is a person who studies glaciers. A glacial geologist studies glacial deposits and glacial erosive features on the landscape. Glaciology and glacial geology are key areas of polar research.


Types

Glaciers can be identified by their geometry and the relationship to the surrounding topography. There are two general categories of glaciation which glaciologists distinguish: ''alpine glaciation'', accumulations or "rivers of ice" confined to valleys; and ''continental glaciation'', unrestricted accumulations which once covered much of the northern continents. *Alpine – ice flows down the valleys of mountainous areas and forms a tongue of ice moving towards the plains below. Alpine glaciers tend to make
topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sc ...
more rugged by adding and improving the scale of existing features. Various features include large ravines called '' cirques'' and
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, which are ridges where the rims of two cirques meet. *Continental – an ice sheet found today, only in high latitudes (
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland i ...
/
Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...
), thousands of square kilometers in area and thousands of meters thick. These tend to smooth out the landscapes.


Zones of glaciers

*
Accumulation Accumulation may refer to: Finance * Accumulation function, a mathematical function defined in terms of the ratio future value to present value * Capital accumulation, the gathering of objects of value Science and engineering * Accumulate (hi ...
zone – where the formation of ice is faster than its removal. *
Ablation Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for a ...
(or wastage) zone – when the sum of melting, calving, and evaporation (sublimation) is greater than the amount of snow added each year.


Glacier equilibrium line and ELA

The glacier equilibrium line is the line separating the glacial accumulation area above from the ablation area below. The equilibrium line altitude (ELA) and its change over the years is a key indicator of the health of a glacier. A long term monitoring of the ELA may be used as indication to
climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
.


Movement

When a
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 as ...
is experiencing an accumulation input by precipitation (snow or refreezing rain) that exceeds the output by ablation, the glacier shows a ''positive glacier mass balance'' and will advance. Conversely, if the loss of volume (from evaporation, sublimation, melting, and calving) exceeds the accumulation, the glacier shows a ''negative glacier mass balance'' and the glacier will melt back. During times in which the volume input to the glacier by precipitation is equivalent to the ice volume lost from calving, evaporation, and melting, the glacier has a steady-state condition. Some glaciers show periods where the glacier is advancing at an extreme rate, that is typically 100 times faster than what is considered normal, it is referred to as a ''surging glacier''. Surge periods may occur at an interval of 10 to 15 years, e.g. on Svalbard. This is caused mainly due to a long lasting accumulation period on subpolar glaciers frozen to the ground in the accumulation area. When the stress due to the additional volume in the accumulation area increases, the pressure melting point of the ice at its base may be reached, the basal glacier ice will melt, and the glacier will surge on a film of meltwater.


Rate of movement

The movement 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 as ...
s is usually slow. Its velocity varies from a few centimeters to a few meters per day. The rate of movement depends upon the factors listed below: *
Temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...
of the ice. A ''polar glacier'' shows cold ice with temperatures well below the freezing point from its surface to its base. It is frozen to its bed. A ''temperate glacier'' is at a melting point temperature throughout the year, from its surface to its base. This allows the glacier to slide on a thin layer of meltwater. Most glaciers in alpine regions are temperate glaciers. *
Gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...
of the slope. * Thickness of the glacier * Subglacial water dynamics


Glacial Terminology

;
Ablation Ablation ( la, ablatio – removal) is removal or destruction of something from an object by vaporization, chipping, erosive processes or by other means. Examples of ablative materials are described below, and include spacecraft material for a ...
: Wastage of the glacier through sublimation, ice melting and iceberg calving. ;
Ablation zone Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any ...
:Area of a glacier in which the annual loss of ice through ablation exceeds the annual gain from
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
. ;
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 ...
:An acute ridge of rock where two cirques meet. ;
Bergschrund A bergschrund (from the German for ''mountain cleft'') or rimaye (from French; ) is a crevasse that forms where moving glacier ice separates from the stagnant ice or firn above. It is often a serious obstacle for mountaineers, who sometimes ab ...
: Crevasse formed near the head of a glacier, where the mass of ice has rotated, sheared and torn itself apart in the manner of a geological fault. ; Cirque, Corrie or cwm : Bowl shaped depression excavated by the source of a glacier. ; Creep : Adjustment to
stress Stress may refer to: Science and medicine * Stress (biology), an organism's response to a stressor such as an environmental condition * Stress (linguistics), relative emphasis or prominence given to a syllable in a word, or to a word in a phrase ...
at a molecular level. ; Flow : Movement (of ice) in a constant direction. ; Fracture : Brittle failure (breaking of ice) under the stress raised when movement is too rapid to be accommodated by creep. It happens, for example, as the central part of a glacier moves faster than the edges. ; Moraine : Accumulated debris that has been carried by a glacier and deposited at its sides (lateral moraine) or at its foot (
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 ...
). ;
Névé Névé is a young, granular type of snow which has been partially melted, refrozen and compacted, yet precedes the form of ice. This type of snow is associated with glacier formation through the process of ''nivation''. Névé that survives a ...
: Area at the top of a glacier (often a cirque) where snow accumulates and feeds the glacier. ;
Horn Horn most often refers to: *Horn (acoustic), a conical or bell shaped aperture used to guide sound ** Horn (instrument), collective name for tube-shaped wind musical instruments *Horn (anatomy), a pointed, bony projection on the head of various ...
: Spire of rock, also known as a pyramidal peak, formed by the
headward erosion Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow, lengthening the stream channel.Essentials of Geology, 3rd Ed, Stephen Marshak It can also refer to ...
of three or more cirques around a single mountain. It is an extreme case of an arête. ; Plucking/Quarrying : Where the
adhesion Adhesion is the tendency of dissimilar particles or surfaces to cling to one another ( cohesion refers to the tendency of similar or identical particles/surfaces to cling to one another). The forces that cause adhesion and cohesion can b ...
of the ice to the rock is stronger than the cohesion of the rock, part of the rock leaves with the flowing ice. ; Tarn : A post-glacial lake in a cirque. ;
Tunnel valley A tunnel valley is a U-shaped valley originally cut under the glacial ice near the margin of continental ice sheets such as that now covering Antarctica and formerly covering portions of all continents during past glacial ages. They can be as l ...
: The tunnel that is formed by hydraulic erosion of ice and rock below an ice sheet margin. The tunnel valley is what remains of it in the underlying rock when the ice sheet has melted.


Glacial deposits


Stratified

;
Outwash An outwash plain, also called a sandur (plural: ''sandurs''), sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the terminus of a glacier. As it flows, the glacier grinds the underlying rock surface and ca ...
sand/gravel :From front of glaciers, found on a plain. ; Kettles :When a lock of stagnant ice leaves a depression or pit. ;
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 :Steep sided ridges of gravel/sand, possibly caused by streams running under stagnant ice. ; Kames :Stratified drift builds up low, steep hills. ;
Varve A varve is an annual layer of sediment or sedimentary rock. The word 'varve' derives from the Swedish word ''varv'' whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as ''Hvarfig lera'' (va ...
s :Alternating thin sedimentary beds (coarse and fine) of a
proglacial lake In geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around th ...
. Summer conditions deposit more and coarser material and those of the winter, less and finer.


Unstratified

;
Till image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
-unsorted :(Glacial flour to boulders) deposited by receding/advancing glaciers, forming moraines, and drumlins. ; Moraines : (Terminal) material deposited at the end; (ground) material deposited as glacier melts; (lateral) material deposited along the sides. ;
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 :Smooth elongated hills composed of till. ; Ribbed moraines :Large subglacial elongated hills transverse to former ice flow.


See also

* Continental Glaciation * Ice cap *
International Glaciological Society The International Glaciological Society (IGS) was founded in 1936 to provide a focus for individuals interested in glaciology, practical and scientific aspects of snow and ice. It was originally known as the "Association for the Study of Snow an ...
*
International Association of Cryospheric Sciences The International Association of Cryospheric Sciences (IACS) is the eighth association of the International Union of Geodesy and Geophysics (IUGG). It was launched by the IUGG Council on 4 July 2007, developing from the International Commission o ...
*
Irish Sea Glacier The Irish Sea Glacier was a huge glacier during the Pleistocene Ice Age that, probably on more than one occasion, flowed southwards from its source areas in Scotland and Ireland and across the Isle of Man, Anglesey and Pembrokeshire. It probabl ...
* List of glaciers *
Cryosphere ] The cryosphere (from the Ancient Greek, Greek ''kryos'', "cold", "frost" or "ice" and ''sphaira'', "globe, ball") is an all-encompassing term for those portions of Earth's surface where water is in solid form, including sea ice, lake ice, ri ...


Notes


Further reading

*Benn, Douglas I. and David J. A. Evans. '' iarchive:glaciersglaciati0000benn, Glaciers and Glaciation''.
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
; Arnold, 1998. *Greve, Ralf and Heinz Blatter. ''Dynamics of Ice Sheets and Glaciers''.
Berlin Berlin ( , ) is the capital and List of cities in Germany by population, largest city of Germany by both area and population. Its 3.7 million inhabitants make it the European Union's List of cities in the European Union by population within ci ...
etc.;
Springer Springer or springers may refer to: Publishers * Springer Science+Business Media, aka Springer International Publishing, a worldwide publishing group founded in 1842 in Germany formerly known as Springer-Verlag. ** Springer Nature, a multinationa ...
, 2009. *Hambrey, Michael and Jürg Alean. ''Glaciers''. 2nd ed.
Cambridge Cambridge ( ) is a College town, university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cam ...
and New York;
Cambridge University Press Cambridge University Press is the university press of the University of Cambridge. Granted letters patent by King Henry VIII in 1534, it is the oldest university press in the world. It is also the King's Printer. Cambridge University Pre ...
, 2004. *Hooke, Roger LeB. ''Principles of Glacier Mechanics''. 2nd ed. Cambridge and New York; Cambridge University Press, 2005. *Paterson, W. Stanley B. ''The Physics of Glaciers''. 3rd ed.
Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...
etc.;
Pergamon Press Pergamon Press was an Oxford-based publishing house, founded by Paul Rosbaud and Robert Maxwell, that published scientific and medical books and journals. Originally called Butterworth-Springer, it is now an imprint of Elsevier. History The ...
, 1994. *van der Veen, Cornelis J. ''Fundamentals of Glacier Dynamics''.
Rotterdam Rotterdam ( , , , lit. ''The Dam on the River Rotte'') is the second largest city and municipality in the Netherlands. It is in the province of South Holland, part of the North Sea mouth of the Rhine–Meuse–Scheldt delta, via the ''"Ne ...
; A. A. Balkema, 1999. *van der Veen, Cornelis J. ''Fundamentals of Glacier Dynamics''. 2nd ed.
Boca Raton, FL Boca Raton ( ; es, Boca Ratón, link=no, ) is a city in Palm Beach County, Florida, United States. It was first incorporated on August 2, 1924, as "Bocaratone," and then incorporated as "Boca Raton" in 1925. The population was 97,422 in the ...
; CRC Press, 2013.


External links


International Glaciological Society (IGS)International Association of Cryospheric Sciences (IACS)Snow, Ice, and Permafrost Group, University of Alaska FairbanksArctic and Alpine Research Group, University of AlbertaGlaciers onlineWorld Data Centre for Glaciology, Cambridge, UKNational Snow and Ice Data Center, Boulder, ColoradoGlobal Land Ice Measurements from Space (GLIMS)Glacial structures – photo atlas North Cascade Glacier Climate ProjectCentre for Glaciology, University of WalesCaltech Glaciology GroupGlaciology Group, University of CopenhagenInstitute of Low Temperature Science, SapporoNational Institute of Polar Research, TokyoGlaciology Group, University of WashingtonGlaciology Laboratory, Universidad de Chile-Centro de Estudios Científicos, Valdivia

Russian Geographical Society (Moscow Centre)

Glaciology Commission

Institute of Meteorology and Geophysics, Univ. of Innsbruck, Austria.
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