Glaciology

Lateral moraine on a glacier joining the Gorner Glacier in Zermatt, Switzerland. The moraine is the high bank of debris on the left side of the image.

Glaciology is the study of natural forms of ice, particularly glaciers, and phenomena related to ice. It includes the study of how glaciers are formed and depleted, how they move, and how they affect the physical landscape, the climate, and living organisms. It is one of the key areas of polar research. It also involves research into glacial history and the reconstruction of past glaciation, thus providing insights into the ice ages. The apparent presence of ice on Mars and Jupiter's moon Europa brings in an extraterrestrial component to the field.

Contents

Thus, glaciology is an interdisciplinary earth science, integrating 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. A person who studies glaciers is called a glaciologist.

Etymology

The word glacier can be traced to the Middle French dialect (Franco-Provençal) term glace, meaning "ice," derived from the Latin term glacies, meaning "frost" or "ice." The word "glaciology" is formed by combining this root with the Greek word λόγος (logos), meaning "speech" or "word."

Types

The process of glaciation is placed in two general categories, described below.

  • Alpine glaciation: It corresponds to accumulations or "rivers of ice" confined to valleys. As ice flows down the slopes of mountainous areas, it forms a "tongue" moving toward the plains below. Alpine glaciers tend to make the topography more rugged.
  • Continental glaciation: It corresponds to unrestricted ice sheets that once covered much of the northern continents but are now found only at high latitudes, such as in Greenland and Antarctica. The sheets are thousands of square kilometers wide and thousands of meters thick. They tend to smooth out the landscape.

Zones of glaciers

  • Accumulation zone: A zone where ice is formed faster than it is removed or lost.
  • Wastage or Ablation zone: A zone where the sum of melting and evaporation (sublimation) of ice is greater than the amount of snow added each year.

Glacial movements and their effects

Striding Edge, an arête viewed from Helvellyn with the corrie Red Tarn to the left and Nethermost Cove to the right.
  • Ablation: In glaciology, ablation means wastage (depletion) of a glacier (or ice or iceberg) through such processes as sublimation, melting, and iceberg calving.
  • Arête: An arête is a thin, almost knife-like, ridge of rock that is typically formed when two glaciers erode adjacent, U-shaped valleys. It may also be formed when two glacial cirques erode headwards toward each other.
  • Bergshrund: A crevasse formed near the head of a glacier, where the moving ice has torn itself apart from stationary ice, in the manner of a geological fault.
  • Cirque (coombe, combe, or corrie): A bowl-shaped depression excavated by the head of a glacier.
  • Creep: The adjustment or deformation of solid material under the influence of stresses.
  • Flow: The movement (of ice) in a constant direction.
  • Fracture: The breaking of ice under stress, especially when movement is too rapid to be accommodated by creep. It happens, for example, as the central part of a glacier moves faster than its edges.
  • Horn: It is a 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 (or quarrying): Plucking is a process by which a glacier erodes chunks of bedrock. When the adhesion of ice to the rock is stronger than the cohesion of the rock, part of the rock leaves with the flowing ice.
  • Tarn: It is a lake formed at the bottom of a cirque when the glacier has melted.
  • Tunnel valley: It is a deep, narrow valley with a U-shaped cross-section, formed by the erosion of rock when the edge of an ice sheet advances up a slope.

Glacial deposits

Stratified

  • Outwash sand/gravel: This is material derived from the front of glaciers, found on a plain.
  • Kettles: A block of stagnant ice leaves a depression or pit.
  • Eskers: These are steep-sided ridges of gravel/sand, possibly caused by streams running under stagnant ice.
  • Kames: The stratified drift builds up low, steep hills.
  • Varves: They are 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

  • Till-unsorted: Ranging from glacial flour to boulders, it is deposited by receding/advancing glaciers, forming moraines, and drumlins.
  • Moraines: They include terminal material deposited at the end; ground material deposited as glacier melts; lateral material deposited along the sides.
  • Drumlins: They consist of smooth, elongated hills composed of till.
  • Ribbed moraines: They are large, subglacial elongated hills, transverse to former ice flow.

See also

References

  • Benn, Douglas I., and David J. A. Evans. 1998. Glaciers & Glaciation. London: Arnold. ISBN 0340584319.
  • Bennett, Matthew, and Neil F. Glasser. 1996. Glacial Geology: Ice Sheets and Landforms. Chichester: Wiley. ISBN 0471963453.
  • Hambrey, M. J., and Jürg Alean. 2004. Glaciers, 2nd edition. Cambridge: Cambridge University Press. ISBN 978-0521828086.
  • Hooke, Roger LeB. 2005. Principles of Glacier Mechanics, 2nd edition. Cambridge: Cambridge University Press. ISBN 978-0521836098.
  • Knight, Peter. 1999. Glaciers. Cheltenham: Stanley Thornes. ISBN 0748740007.

External links

All links retrieved June 23, 2017.


General subfields within the earth sciences
Atmospheric sciences | Geodesy | Geology | Geophysics | Glaciology
Hydrology | Oceanography | Soil science


  Physical geography
Land ocean ice cloud 1024.jpg Biogeography · Climatology & paleoclimatology · Coastal/Marine studies · Geodesy · Geomorphology · Glaciology · Hydrology & Hydrography · Landscape ecology · Limnology · Oceanography · Palaeogeography · Pedology · Quaternary Studies

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