© BASRemote sensing reveals the profile of the ice-locked peaks (lower graph).
A series of prefabricated buildings perched on stilts create a boxy but unremarkable hamlet on the Antarctic ice. What is astonishing about this research base is that it is set 500 metres above the peaks of a 3500-metre mountain range.
The Gamburtsev mountains are not a new discovery - they were first located 50 years ago by a team of Russian scientists. But little was known about their scale and morphology. Now, an international team has returned with data revealing that if you could strip away the ice, the view would look rather like the European Alps.
The team set up camp in two locations near to Dome A - the highest point on the ice sheet, where temperatures average -30 °C.
For weeks they flew two aircraft over the ice, exploring the hidden peaks with radar and aeromagnetic sensors, and covering a distance equivalent to three trips around the globe. Gravity sensors on the surface of the ice collected yet more data.
© IPYThe researchers studied the Gamburtsev mountains, located at the centre of Antarctica, using instruments mounted on airplanes.
"We now know that not only are the mountains the size of the European Alps, but they also have similar peaks and valleys," says Fausto Ferraccioli, a geophysicist with the British Antarctic Survey. "This adds even more mystery about how the vast East Antarctic ice sheet formed."
The Gamburtsev range is thought to be the birthplace of the ice sheet. It sits at the centre of the continent, far from warming sea air, and reaches between 3000 and 4000 metres above sea level. This means that some 35 million years ago when the ice sheet started to form, the range would have been very cold.
It is unclear, though, how fast the ice spread across the continent, and whether the ice formed the jagged landscape or the peaks were there first.
If the ice sheet formed slowly, glaciologists would expect to see rounded plateaus in places where it eroded the rock, but the surveys found no such soft landscapes. This may suggest that the ice grew very rapidly, effectively preserving an ancient Alpine landscape beneath kilometres of ice. On the other hand, Ferraccioli says it would be foolish to ignore the possibility that the flow of rivers and glaciers carved deep valleys as the ice sheet was forming.
How the mountains came to be in the first place is also something of a mystery. One theory - that they were volcanic peaks - was weakened by data
published last year, which found that the sediment downstream from the peaks is not volcanic in origin.Hidden fault?
Yet it is difficult to see how the peaks could have grown out of the collision of two tectonic plates - East Antarctica is generally thought to be a homogenous, stable plate.
One of the first tasks in sifting through the data, says Ferraccioli, will be to see if there is any evidence of major differences in the geology of the mountains. Such differences could be a sign that there is an inactive fault line beneath the ice that could have formed the range.
Alternatively, a broad collision elsewhere could have pushed the mountains up within the plate - a bit like a lump of play dough being squished between two wooden blocks. Two portions of the ancient supercontinent Gondwana collided at roughly the same time as the Gamburtsev range is thought to have first emerged, but quite where that happened isn't known.
One thing is certain from the preliminary data: there's liquid water in them there valleys. "The temperatures at our camps hovered around -30 °C," says Robin Bell, of the Lamont-Doherty Earth Observatory at Columbia University. "But three kilometres beneath us, at the bottom of the ice sheet, we saw liquid water in the valleys. The radar mounted on the wings of the aircraft transmitted energy through the thick ice and let us know that it was much warmer at the base of the ice sheet."