Sentences with phrase «bottom of the ice sheet»

But Robin Bell, a geophysicist at Columbia University's Lamont Doherty Earth Observatory, reports with colleagues in Nature Geoscience that they used ice - penetrating radar to identify ragged blocks of ice as tall as skyscrapers and as wide as the island of Manhattan at the very bottom of the ice sheet.

The hope is that the cables could reveal secrets about what's happening underneath the ice sheets, especially about melting at the so - called grounding line, the place where the bottom of an ice sheet meets the slightly warmer ocean.

«All of a sudden it allows us to understand how dynamic the bottom of the ice sheet was — or was not — over that long time period,» Schroeder says.

The drillers finally reached the bottom of the ice sheet on January 7 at 3:55 P.M. Pacific time.

The digitized data extend the record of changes at the bottom of the ice sheet, such as the formation of channels as Antarctica's ice flows, by more than two decades.

That might include draining away the water that lubricates the bottom of an ice sheet, speeding its progress to the sea, or installing barriers to prevent warming ocean waters from hitting the bottom of such glaciers and hastening meltdown.

The scientists stressed the need for more study of the conditions at the bottom of the ice sheet because of a proposal published in the Bulletin of the Atomic Scientists in 1973 to use the ice sheet as a dumping ground for radioactive waste.

The smooth depression, we now understand, was a result of the bottom of the ice sheet floating free and frictionless as it passed over water instead of bedrock 21/2?

«Modelers need an estimate of the heat flow, and they need to know something about the geological conditions at the bottom of the ice sheet in order to estimate drag.

This dirty ice represented muddy water from Lake Vostok that had frozen back onto the bottom of the ice sheet.

The lakes are fed by geothermal heat that seeps up from the Earth's interior, melting away the bottom of the ice sheet at a rate of several dime - thicknesses per year and liberating water from the ice.

Scientists have long known this meltwater flows in streams along the ice sheet's surface before disappearing down chutes that take it tumbling to the bottom of the ice sheet, where the ice scrapes against bedrock.

Previous observations of the thickness of Antarctic sea ice produced a mean draught — the depth between the waterline and the bottom of the ice sheet — of around 1 meter; the new work gives a mean draught of over 3 meters.

Such lakes of water pool at the bottom of an ice sheet or glacier, and were known to be scattered under parts of Antarctica.

Other recent findings of Bell's — that refreezing meltwater can warp the bottom of the ice sheet — combine with the new study to show «there's a richer range of processes that can happen at the bottom of the ice sheet than we thought,» Bell said.

«They all started in places where the bottom of the ice sheet is wet.

The next step is to survey the identified drill sites to measure the ice thickness and temperature at the bottom of the ice sheet before selecting a final drill location.

«Heat that comes up from the interior of the Earth contributes to the amount of melt on the bottom of the ice sheet — so it's extremely important to understand the pattern of that heat and how it's distributed at the bottom of the ice sheet,» said Soroush Rezvanbehbahani, a doctoral student in geology at the University of Kansas who spearheaded the research.

But as the glacier grinds slowly over the lake, small amounts of lake water freeze onto the bottom of the ice sheet — and scientists have drilled out samples of this ice and scoured it for signs of life.

This canyon drained a large meltwater lake on the surface of the ice into a moulin, or under - ice channel that flows to the bottom of the ice sheet.

The NASA study is about the bottom of the ice sheet.

«The study itself is about steady state conditions that would exist at the bottom of the ice sheet for many many millions of years,» he said.

Perhaps they represent glacial advances that overrun terminal moraines and then freeze their rock into the bottom of the ice sheet.

This canyon drained a large meltwater lake on the surface of the ice into a moulin, or under - ice channel that flows to the bottom of the ice sheet.

Melting and refreezing at the bottom of ice sheets warps the layer - cake structure above, as seen in this radar image from Greenland.