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
Previously Unknown Volcanic Eruption Helped Trigger Cold Decade
Space & Earth / Earth Sciences
Oct 29, 2009 |
4.3 / 5 (27) |
9
(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.
West Antarctic ice sheet may not be losing ice as fast as once thought
Space & Earth / Earth Sciences
Oct 19, 2009 |
4.1 / 5 (10) |
4
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 ...
Long debate ended over cause, demise of ice ages -- may also help predict future
Space & Earth / Earth Sciences
Aug 06, 2009 |
4.4 / 5 (23) |
63
Researchers have largely put to rest a long debate on the underlying mechanism that has caused periodic ice ages on Earth for the past 2.5 million years - they are ultimately linked to slight shifts in solar radiation caused ...
Ice Sheets Can Retreat 'In a Geologic Instant,' Study of Prehistoric Glacier Shows
Space & Earth / Earth Sciences
Jun 21, 2009 |
4.5 / 5 (61) |
20
(PhysOrg.com) -- Modern glaciers, such as those making up the Greenland and Antarctic ice sheets, are capable of undergoing periods of rapid shrinkage or retreat, according to new findings by paleoclimatologists ...
Catastrophic sea levels 'distinct possibility' this century: study
Space & Earth / Earth Sciences
Apr 15, 2009 |
4.4 / 5 (89) |
25
A breakthrough study of fluctuations in sea levels the last time Earth was between ice ages, as it is now, shows that oceans rose some three meters in only decades due to collapsing ice sheets.
West Antarctic ice comes and goes, rapidly
Space & Earth / Earth Sciences
Mar 18, 2009 |
4.3 / 5 (16) |
8
Researchers today worry about the collapse of West Antarctic ice shelves and loss of the West Antarctic ice sheet, but little is known about the past movements of this ice. Now climatologists from Penn State ...
Team confirms Alps-like mountain range under East Antarctic Ice Sheet
Space & Earth / Earth Sciences
Feb 24, 2009 |
4.6 / 5 (8) |
2
(PhysOrg.com) -- Flying twin-engine light aircraft the equivalent of several trips around the globe and establishing a network of seismic instruments across an area the size of Texas, a U.S.-led, international ...
New data show much of Antarctica is warming more than previously thought
Jan 21, 2009 |
3 / 5 (36) |
31
(PhysOrg.com) -- Scientists studying climate change have long believed that while most of the rest of the globe has been getting steadily warmer, a large part of Antarctica - the East Antarctic 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.
.jpg)
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.
Radar Map of Buried Mars Layers Matches Climate Cycles
Space & Earth / Space Exploration
Sep 22, 2009 |
4.3 / 5 (7) |
1
(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 |
3.9 / 5 (18) |
0
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 ...
New CO2 data helps unlock the secrets of Antarctic formation
Space & Earth / Earth Sciences
Sep 13, 2009 |
4.1 / 5 (15) |
6
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.
Map Characterizes Active Lakes Below Antarctic Ice (w/ Video)
Space & Earth / Earth Sciences
Aug 25, 2009 |
4 / 5 (6) |
0
(PhysOrg.com) -- Lakes in Antarctica, concealed under miles of ice, require scientists to come up with creative ways to identify and analyze these hidden features. Now, researchers using space-based lasers ...
3.2-Million-Year Temperature History from Tiny Fossils
Space & Earth / Earth Sciences
Aug 05, 2009 |
3.8 / 5 (12) |
5
(PhysOrg.com) -- People often talk about greenhouse gases and their effect on the earth's climate as if those effects were new. But greenhouse gases have been around for hundreds of millennia, playing a key ...
