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
From Greenhouse to Icehouse
Space & Earth / Earth Sciences
Nov 24, 2009 |
4.8 / 5 (12) |
9
A new study that reconstructed ocean temperatures from millions of years ago could provide new insight into how the Earth responds to climate change.
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Greenland ice cap melting faster than ever
Space & Earth / Earth Sciences
Nov 12, 2009 |
3.6 / 5 (32) |
25
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.
LSU gets to the bottom of things -- in Antarctica
Space & Earth / Earth Sciences
Nov 24, 2009 |
4.3 / 5 (3) |
1
Antarctica has long held secrets of the earth's history locked in its icy depths, and until recently, there has been very little information on the environments that have been sealed beneath miles of ice for millions of years. ...
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Big freeze plunged Europe into ice age in months
Space & Earth / Earth Sciences
Nov 30, 2009 |
3.9 / 5 (16) |
7
In the film, 'The Day After Tomorrow' the world enters the icy grip of a new glacial period within the space of just a few weeks. Now new research shows that this scenario may not be so far from the truth after all.
Icebergs head from Antarctica for New Zealand
Space & Earth / Earth Sciences
Nov 24, 2009 |
3 / 5 (5) |
1
(AP) -- Ships in the south Pacific Ocean have been alerted that hundreds of icebergs believed to have split off Antarctic ice shelves are drifting north toward New Zealand, officials said Tuesday.
Ships warned about icebergs headed for New Zealand
Space & Earth / Earth Sciences
Nov 25, 2009 |
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0
(AP) -- Ships are on alert and maritime authorities are monitoring the movements of hundreds of menacing icebergs drifting toward New Zealand in the southern Pacific Ocean, officials said.
First comprehensive review of the state of Antarctica's climate
Space & Earth / Earth Sciences
Dec 01, 2009 |
3.7 / 5 (10) |
3
The first comprehensive review of the state of Antarctica's climate and its relationship to the global climate system is published this week by the Scientific Committee on Antarctic Research (SCAR). The review - Antarctic ...
In Greenland, warming fuels dream of hidden wealth
Nov 27, 2009 |
3.5 / 5 (4) |
1
(AP) -- Gert Ignatiussen returns to this fjord-front Inuit town with the spoils of his hunting trip. Six seals, all killed with a single shot to the head.
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