Ice sheet
hideAn ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km² (20,000 mile²). The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum (LGM) the Laurentide ice sheet covered much of Canada and North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.
Ice sheets are bigger than ice shelves or glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery.
Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams.
The present-day polar ice sheets are relatively young in geological terms. The Antarctic Ice Sheet first formed as a small ice cap (maybe several) in the early Oligocene, but retreating and advancing many times until the Pliocene, when it came to occupy almost all of Antarctica. The Greenland ice sheet did not develop at all until the late Pliocene, but apparently developed very rapidly with the first continental glaciation. This had the unusual effect of allowing fossils of plants that once grew on present-day Greenland to be much better preserved than with the slowly forming Antarctic ice sheet.
For more information about Ice sheet, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with ice sheet
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Greenland ice cap melting faster than ever
Space & Earth / Earth Sciences
Nov 12, 2009 |
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Satellite observations and a state-of-the art regional atmospheric model have independently confirmed that the Greenland ice sheet is loosing mass at an accelerating rate, reports a new study in Science.
Previously Unknown Volcanic Eruption Helped Trigger Cold Decade
Space & Earth / Earth Sciences
Oct 29, 2009 |
4.3 / 5 (27) |
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(PhysOrg.com) -- A team of chemists from the U.S. and France has found compelling evidence of a previously undocumented large volcanic eruption that occurred exactly 200 years ago, in 1809.
North Carolina Sea Levels Rising Three Times Faster Than in Previous 500 Years, Study Says
Space & Earth / Earth Sciences
Oct 28, 2009 |
2.5 / 5 (10) |
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PHILADELPHIA -- An international team of environmental scientists led by the University of Pennsylvania has shown that sea-level rise, at least in North Carolina, is accelerating. Researchers found 20th-century sea-level ...
Researchers to study hidden lakes beneath West Antarctic ice sheet
Space & Earth / Earth Sciences
Oct 21, 2009 |
5 / 5 (3) |
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(PhysOrg.com) -- UC Santa Cruz researchers are among the leaders of a major Antarctic research project in which scientists will drill through a half-mile of ice to penetrate subglacial Lake Whillans and study ...
West Antarctic ice sheet may not be losing ice as fast as once thought
Space & Earth / Earth Sciences
Oct 19, 2009 |
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New ground measurements made by the West Antarctic GPS Network (WAGN) project, composed of researchers from The University of Texas at Austin, The Ohio State University, and The University of Memphis, suggest ...
NASA flies to Antarctica for largest airborne polar ice survey
Space & Earth / Earth Sciences
Oct 08, 2009 |
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NASA begins a series of flights Oct. 15 to study changes to Antarctica's sea ice, glaciers and ice sheets. The flights are part of Operation Ice Bridge, a six-year campaign that is the largest airborne survey ever made of ...
Peering under the ice of a collapsing polar coast
Space & Earth / Earth Sciences
Oct 07, 2009 |
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Starting this month, a giant NASA DC-8 aircraft loaded with geophysical instruments and scientists will buzz at low level over the coasts of West Antarctica, where ice sheets are collapsing at a pace far beyond ...
NIU will use robotic submarine to explore melting occurring below Antarctic ice
Space & Earth / Earth Sciences
Oct 05, 2009 |
3 / 5 (2) |
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(PhysOrg.com) -- Northern Illinois University geologists are helping to lead a multi-million-dollar, five-year investigation of melting near the base of the West Antarctic Ice Sheet (WAIS) using a 24-foot-long ...
NASA Ice Satellite Maps Profound Polar Thinning
Space & Earth / Earth Sciences
Sep 24, 2009 |
3.3 / 5 (11) |
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(PhysOrg.com) -- Researchers have used NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) to compose the most comprehensive picture of changing glaciers along the coast of the Greenland and Antarctic ...
Lasers from space show thinning of Greenland and Antarctic ice sheets
Space & Earth / Earth Sciences
Sep 23, 2009 |
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The most comprehensive picture of the rapidly thinning glaciers along the coastline of both the Antarctic and Greenland ice sheets has been created using satellite lasers. The findings are an important step forward in the ...
Radar Map of Buried Mars Layers Matches Climate Cycles
Space & Earth / Space Exploration
Sep 22, 2009 |
4.3 / 5 (7) |
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(PhysOrg.com) -- New, three-dimensional imaging of Martian north-polar ice layers by a radar instrument on NASA's Mars Reconnaissance Orbiter is consistent with theoretical models of Martian climate swings ...
Melting of the Greenland ice sheet mapped
Space & Earth / Earth Sciences
Sep 16, 2009 |
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Will all of the ice on Greenland melt and flow out into the sea, bringing about a colossal rise in ocean levels on Earth, as the global temperature rises? The key concern is how stable the ice cap actually ...
Egg-shaped legacy of Britain's mobile ice-sheet
Space & Earth / Earth Sciences
Sep 16, 2009 |
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(PhysOrg.com) -- The ice sheets that sculpted the landscape of northern Britain moved in unexpected ways and left distinctive egg-shaped features according to new research.
New CO2 data helps unlock the secrets of Antarctic formation
Space & Earth / Earth Sciences
Sep 13, 2009 |
4.3 / 5 (13) |
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The link between declining CO2 levels in the earth's atmosphere and the formation of the Antarctic ice caps some 34 million years ago has been confirmed for the first time in a major research study.
Greenland's melt mystery unfolds, at glacial pace
Space & Earth / Earth Sciences
Sep 10, 2009 |
3.1 / 5 (8) |
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(AP) -- Suddenly and without warning, the gigantic river of ice sped up, causing it to spit icebergs ever faster into the ocean off southeastern Greenland.
