Glaciology
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Glaciology is the study of glaciers, or more generally the study of ice and natural phenomena that involve ice. The word glacier is derived from the Latin glacies, meaning ice or frost.
Glaciology is an interdisciplinary earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds the fields of Human geography and anthropology. The presence of ice on Mars and Europa brings in an extraterrestrial component to the field.
Contents
Overview
Areas of study within glaciology include glacial history and the reconstruction of past glaciation patterns, effects of glaciers on climate and vice versa, the dynamics of ice movement, the contributions of glaciers to erosion and geomorphology, lifeforms that live in the ice, and so forth.Not surprisingly, glaciology is one of the key areas supported by polar research.
Types
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 valley of mountainous areas and forms an apron of moving ice onto the plains below. Alpine glaciers tend to make the topography more rugged.
- Continental - an ice sheet found only in high latitudes (Greenland/Antarctica), thousands of square kilometers wide and thousands of meters thick. These tend to smooth out the landscape.
Zones of glaciers
- Accumulation
- Wastage
Movement
- Ablation
- wastage through evaporation and melting
- Arête
- an acute ridge where two cirques abut.
- Bergshrund
- crevasse formed at the head of a glacier, where it breaks away from the mountain face.
- 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 movinges faster than the edges.
- Horn
- spire of rock formed by the headward erosion of a ring of cirques around a single mountain. It is an extreme case of an arête.
- 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 lake formed in the bottom of a cirque
- Tunnel valley
- The tunnel is that 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 sand/gravel
- from front of glaciers, found on a plain
- Kettles
- block 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
- thin sedimentary beds (coarse to fine), summer deposits more material and in the winter, less.
Unstratified
- 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.
References
- Hambrey, Michael and Jürg Alean. Glaciers 2nd ed. Cambridge University Press, 2004. ISBN 0-521-82808-2
- Benn, Douglas I. and David J. A. Evans. Glaciers and Glaciation. London; Arnold, 1998. ISBN 0-340-58431-9
- Knight, Peter G. Glaciers Cheltenham; Nelson Thornes, 1999. ISBN 0-7487-4000-7
See also
External links
- [International Glaciological Society]
- [Glaciers online]
- [World Data Centre for Glaciology, Cambridge, UK]
- [National Snow and Ice Data Center, Boulder, Colorado]
- [Global Land Ice Measurements from Space, USGS]
- [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]
| General subfields within the earth sciences |
|---|
| Atmospheric sciences | Geodesy | Geology | Geophysics | Glaciology |
| Hydrology | Oceanography | Soil science |
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