Page last updated at 18:04 GMT, Tuesday, 14 October 2008 19:04 UK

Expedition set for 'ghost peaks'

By Jonathan Amos
Science reporter, BBC News

Tented camp (BAS)
Working deep in the interior is challenging at the best of times

It is perhaps the last great Antarctic expedition - to find an explanation for why there is a great mountain range buried under the White Continent.

The Gamburtsevs match the Alps in scale but no-one has ever seen them because they are covered by up to 4km of ice.

Geologists struggle to understand how such a massif could have formed and persisted in the middle of Antarctica.

Now, an international team is setting out on a deep-field survey to try to get some answers.

The group comprises scientists, engineers, pilots and support staff from the UK, the US, Germany, Australia, China and Japan.

It's rather like being an archaeologist and opening up a tomb in a pyramid and finding an astronaut sitting inside. It shouldn't be there
Dr Robin Bell, Lamont-Doherty Earth Observatory

The ambitious nature of the project - working in Antarctica's far interior - has required an exceptional level of co-ordination and co-operation.

"You can almost think about it as exploring another planet - but on Earth," said Dr Fausto Ferraccioli from the British Antarctic Survey.

"This region is a complete enigma. It's in the middle of the continent. Most mountain ranges are on the edges of continents, and we really can't understand what these mountains are doing in the centre."

The AGAP (Antarctica's Gamburtsev Province) project will establish two camps from where the team will map the subglacial range using surface and airborne instruments.

EXPLORING THE SUBGLACIAL GAMBURTSEV MOUNTAINS
Graphic (BBC)
1. Aircraft will use radar to detect ice thickness and layering, and to map the shape of the deeply buried bedrock
2. The planes will also conduct gravity and magnetic surveys to glean more information about the mountains' structure
3. By listening to seismic waves passing through the range, scientists can probe rock properties deep in the Earth

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Dr Fausto Ferraccioli describes the equipment onboard the aircraft

The Gamburtsevs were discovered by a Soviet team making a seismic survey on a traverse across the ice in the late 1950s. The hidden rocky prominence was totally unexpected; scientists thought the interior of the continent would be relatively flat.

"There are two easy ways to make mountains," explained Dr Robin Bell, from the Lamont-Doherty Earth Observatory, who is a lead US researcher on the expedition.

"One is colliding continents, but after they collide they tend to erode; and the last collision was 500-million-plus years ago. They shouldn't be there.

Dr Robin Bell says it will be like doing an "X-ray of the ice sheet"

"The other way is a hotspot, [with volcanoes punching through the crust] like in Hawaii; but there's no good evidence for underneath the ice sheet being that hot.

"I like to say it's rather like being an archaeologist and opening up a tomb in a pyramid and finding an astronaut sitting inside. It shouldn't be there."

The mountains are believed to have been a key nucleation point for the vast East Antarctic Ice Sheet.

It is thought that as Earth's climate cooled just over 30 million years ago, the snows that fell on the mountains produced mighty glaciers, which then merged to form one giant spreading ice-mass.

EXPANDING ICE SHEET

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A better understanding of these events could give clues as to how Antarctica might evolve in the coming centuries if, as expected, the Earth continues its current warming trend.

The AGAP project is a flagship endeavour of International Polar Year - the global science community's concerted push to try to answer the big questions about the Earth's northern and southern extremes.

The challenging nature of the expedition has required that expertise be drawn from across the polar community. Supplying such remote camps is a major logistical exercise; working in them - at temperatures 30-40 degrees below zero Celsius - is bound to be physically demanding.

Two survey aircraft will sweep back and forth across the ice to map the shape of the mountains. The planes will be equipped with ice-penetrating radar and instruments to measure the local gravitational and magnetic fields.

Ice core (CNRS)
Air bubbles trapped in old ices record environmental conditions

Information on the deeper structure of the Gamburtsevs will come from a network of seismometers that will listen to earthquake signals passing through the rock from the other side of the globe.

"We'll map everything from the detailed ripples on the surface of the ice sheet down to the temperature structure hundreds of kilometres in the Earth, so we'll have everything from the layering in the ice to what the nature of the rocks are," said Dr Bell.

Another important aim of the project is to find a place to drill for ancient ices. By examining bubbles of air trapped in compacted snow, it is possible for researchers to glean details about past environmental conditions.

Not only can they see concentrations of carbon dioxide and methane - the two principal human-produced gases now blamed for global warming - but they can also gauge past temperatures from the samples.

Somewhere in the Gamburtsev region there could be a location were it is possible to drill down to ices that are more than a million years old. This is at least 200,000 years older than the most ancient ices currently in the possession of scientists.

The expedition gets under way in the next few weeks and will take some two-and-a-half months to complete.

Jonathan.Amos-INTERNET@bbc.co.uk




SEE ALSO
White Continent in its full glory
27 Nov 07 |  Science & Environment
Huge polar study ready to begin
26 Feb 07 |  Science & Environment
CO2 'highest for 650,000 years'
24 Nov 05 |  Science & Environment
Survey targets 'ghost' mountains
13 Dec 06 |  Science & Environment

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