Glaciology (from Latinglacies 'frost, ice', and Ancient Greekλόγος (logos) 'subject matter'; lit.'study of ice') is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice.
Lateral moraine on a glacier joining the Gorner Glacier, Zermatt, Swiss Alps. The moraine is the high bank of debris in the top left hand quarter of the image.
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 glaciers.
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.
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 more rugged by adding and improving the scale of existing features. Various features include large ravines called cirques and arêtes, which are ridges where the rims of two cirques meet.
Continental – an ice sheet found today, only in high latitudes (Greenland/Antarctica), thousands of square kilometers in area and thousands of meters thick. These tend to smooth out the landscapes.
Zones of glaciers
Accumulation zone – where the formation of ice is faster than its removal.
Ablation (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.
Movement
Khurdopin glacier and Shimshal River, Gilgit-Baltistan, northern Pakistan 2017. Several glaciers flow into the Shimshal Valley, and are prone to blocking the river. Khurdopin glacier surged in 2016–17, creating a sizable lake.[2]
Glaciers of Shimsal Valley from space, May 13, 2017. Khurdopin glacier has dammed the Shimshal River, forming a glacial lake. The river has started to carve a path through the toe of the glacier. By early August 2017, the lake had completely drained.
When a glacier 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 glaciers 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 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.
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.
Spire of rock, also known as a pyramidal peak, formed by the headward erosion of three or more cirques around a single mountain. It is an extreme case of an arête.
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.
Alternating thin sedimentary beds (coarse and fine) of a proglacial lake. Summer conditions deposit more and coarser material and those of the winter, less and finer.
International Association of Cryospheric Sciences (IACS)
Arctic and Alpine Research Group, University of Alberta
Glaciers online
World Data Centre for Glaciology, Cambridge, UK
National Snow and Ice Data Center, Boulder, Colorado
Global Land Ice Measurements from Space (GLIMS)
Glacial structures – photo atlas
Caltech Glaciology Group
Institute of Low Temperature Science, Sapporo
National Institute of Polar Research, Tokyo
Glaciology Group, University of Washington
Glaciology Laboratory, Universidad de Chile-Centro de Estudios Científicos, Valdivia
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January 07, 2023
glaciology, this, article, includes, list, general, references, lacks, sufficient, corresponding, inline, citations, please, help, improve, this, article, introducing, more, precise, citations, february, 2011, learn, when, remove, this, template, message, from. This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations February 2011 Learn how and when to remove this template message Glaciology from Latin glacies frost ice and Ancient Greek logos logos subject matter lit study of ice is the scientific study of glaciers or more generally ice and natural phenomena that involve ice Lateral moraine on a glacier joining the Gorner Glacier Zermatt Swiss Alps The moraine is the high bank of debris in the top left hand quarter of the image Glaciologist Erin Pettit in Antarctica 2016 Glaciology is an interdisciplinary Earth science that integrates geophysics geology physical geography geomorphology climatology meteorology hydrology biology and ecology The impact of glaciers on people includes the fields of human geography and anthropology The discoveries of water ice on the Moon Mars Europa and Pluto add an extraterrestrial component to the field which is referred to as astroglaciology 1 Contents 1 Overview 2 Types 3 Zones of glaciers 4 Glacier equilibrium line and ELA 5 Movement 5 1 Rate of movement 6 Glacial Terminology 7 Glacial deposits 3 7 1 Stratified 7 2 Unstratified 8 See also 9 Notes 10 Further reading 11 External linksOverview EditA 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 glaciers 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 Edit A Bylot Island glacier Sirmilik National Park Nunavut This mountain glacier is one of many coming down from the interior ice cap on top of the Byam Martin Mountains 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 more rugged by adding and improving the scale of existing features Various features include large ravines called cirques and aretes which are ridges where the rims of two cirques meet Continental an ice sheet found today only in high latitudes Greenland Antarctica thousands of square kilometers in area and thousands of meters thick These tend to smooth out the landscapes Zones of glaciers EditAccumulation zone where the formation of ice is faster than its removal Ablation 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 EditThe 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 Movement Edit Khurdopin glacier and Shimshal River Gilgit Baltistan northern Pakistan 2017 Several glaciers flow into the Shimshal Valley and are prone to blocking the river Khurdopin glacier surged in 2016 17 creating a sizable lake 2 Glaciers of Shimsal Valley from space May 13 2017 Khurdopin glacier has dammed the Shimshal River forming a glacial lake The river has started to carve a path through the toe of the glacier By early August 2017 the lake had completely drained When a glacier 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 Edit The movement of glaciers 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 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 of the slope Thickness of the glacier 3 Subglacial water dynamicsGlacial Terminology EditAblation Wastage of the glacier through sublimation ice melting and iceberg calving Ablation zone Area of a glacier in which the annual loss of ice through ablation exceeds the annual gain from precipitation Arete An acute ridge of rock where two cirques meet Bergschrund 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 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 Neve Area at the top of a glacier often a cirque where snow accumulates and feeds the glacier Horn Spire of rock also known as a pyramidal peak formed by the headward erosion of three or more cirques around a single mountain It is an extreme case of an arete Plucking Quarrying Where the adhesion 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 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 3 Edit A kettle pond in Hossa Suomussalmi municipality Finland Stratified Edit Outwash sand gravel From front of glaciers found on a plain Kettles When a lock of stagnant ice leaves a depression or pit Eskers Steep sided ridges of gravel sand possibly caused by streams running under stagnant ice Kames Stratified drift builds up low steep hills Varves Alternating thin sedimentary beds coarse and fine of a proglacial lake Summer conditions deposit more and coarser material and those of the winter less and finer Unstratified Edit Drowned drumlin in Clew Bay Ireland Till 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 Drumlins Smooth elongated hills composed of till Ribbed moraines Large subglacial elongated hills transverse to former ice flow See also EditContinental Glaciation Ice cap International Glaciological Society International Association of Cryospheric Sciences Irish Sea Glacier List of glaciers CryosphereNotes Edit Williams Richard S 1987 Summary Remarks Annals of Glaciology 9 254 255 Bibcode 1987AnGla 9 254W doi 10 3189 S0260305500000987 Khurdopin glacier amp Shimshal River Pakistan a b Mahapatra G B 1994 Text book of Physical Geology Nazia printers Delhi p 269 ISBN 81 239 0110 0 Further reading EditBenn Douglas I and David J A Evans Glaciers and Glaciation London Arnold 1998 ISBN 0 340 58431 9 Greve Ralf and Heinz Blatter Dynamics of Ice Sheets and Glaciers Berlin etc Springer 2009 ISBN 978 3 642 03414 5 Hambrey Michael and Jurg Alean Glaciers 2nd ed Cambridge and New York Cambridge University Press 2004 ISBN 0 521 82808 2 Hooke Roger LeB Principles of Glacier Mechanics 2nd ed Cambridge and New York Cambridge University Press 2005 ISBN 0 521 54416 5 Paterson W Stanley B The Physics of Glaciers 3rd ed Oxford etc Pergamon Press 1994 ISBN 0 08 037944 3 van der Veen Cornelis J Fundamentals of Glacier Dynamics Rotterdam A A Balkema 1999 ISBN 90 5410 471 6 van der Veen Cornelis J Fundamentals of Glacier Dynamics 2nd ed Boca Raton FL CRC Press 2013 ISBN 14 398 3566 7External links Edit Wikimedia Commons has media related to Glaciology This article s use of external links may not follow Wikipedia s policies or guidelines Please improve this article by removing excessive or inappropriate external links and converting useful links where appropriate into footnote references October 2020 Learn how and when to remove this template message International Glaciological Society IGS International Association of Cryospheric Sciences IACS Snow Ice and Permafrost Group University of Alaska Fairbanks Arctic and Alpine Research Group University of Alberta Glaciers online World Data Centre for Glaciology Cambridge UK National Snow and Ice Data Center Boulder Colorado Global Land Ice Measurements from Space GLIMS Glacial structures photo atlas North Cascade Glacier Climate Project Centre for Glaciology University of Wales Caltech Glaciology Group Glaciology Group University of Copenhagen Institute of Low Temperature Science Sapporo National Institute of Polar Research Tokyo Glaciology Group University of Washington Glaciology Laboratory Universidad de Chile Centro de Estudios Cientificos Valdivia Russian Geographical Society Moscow Centre Glaciology Commission Institute of Meteorology and Geophysics Univ of Innsbruck Austria Retrieved from https en wikipedia org w index php title Glaciology amp oldid 1130930182, wikipedia, wiki, 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