Glaciology

From New World Encyclopedia
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 glaciers, or, more generally, the study of ice and natural phenomena involving ice. It is one of the key areas of polar research.

As an interdisciplinary earth science, glaciology 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. Glaciology also includes glacial history and the reconstruction of past glaciation. The presence of ice on Mars and Europa brings in an extraterrestrial component to the field. 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: A zone where ice is formed faster than it is removed or lost.
  • Wastage or Ablation: A zone where the sum of melting and evaporation (sublimation) of ice is greater than the amount of snow added each year.

Movement

Ablation
wastage of the glacier through sublimation, ice melting and iceberg calving.
Arête
an acute ridge of rock where two cirques abut.
Bergshrund
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 (coombe, combe, or corrie)
A bowl-shaped depression excavated by the head 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 at the bottom of a cirque when the glacier has melted.
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
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
(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

References
ISBN links support NWE through referral fees

  • 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 ed. Cambridge, UK: Cambridge University Press. ISBN 978-0521828086.
  • Hooke, Roger LeB. 2005. Principles of Glacier Mechanics. 2nd ed. Cambridge, UK: Cambridge University Press. ISBN 978-0521836098.
  • Knight, Peter. 1999. Glaciers. Cheltenham: Stanley Thornes. ISBN 0748740007.

External links

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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