Ancient Antarctic Mountains Found Under Miles of Ice

June 3, 2009 -- Millions of years ago, rivers ran in Antarctica through craggy mountain valleys that were strangely similar to the modern European Alps, Chinese and British scientists reported on Wednesday.

In a study published by the British journal Nature, the scientists described a vast terrain that had been hidden beneath ice up to two miles thick for eons, until new imaging technology recently uncovered them.

"The landscape has probably been preserved beneath the ice sheet for around 14 million years," the paper said.

The imaging revealed "classic Alpine topography" similar to Europe's Alps, showing that rivers had once existed on Antarctica and had cut their way through the mountains. Later, these valleys were gouged and deepened by glaciers.

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The team conducted two separate probes, one in 2004-2005 and another in 2007-2008, using deep-penetrating ground radar in a squared-off section of the icy continent, measuring 18 miles on each side. They started from a set point each time -- a 13-thousand-foot mountain named Dome Argus.

Beneath Dome Argus, scientists discovered an ice sheet between 5,410 and 10,285 feet thick that smothers the Gamburtsev mountains, a range named after a Soviet geophysicist, Grigoriy Gamburtsev, who first detected the peaks in 1958.

The research also looked at deep-sea isotope records and theorized there was a period of global cooling, called the Eocene, between 52 and 34 million years ago, that eventually led to the formation of the polar ice caps.

Then came two progressively dramatic periods of cooling, which scientists have linked to a decline in naturally-produced greenhouse gas levels in the atmosphere -- the same gases that, now man-made, are blamed for global warming today.

According to their research, changes in Earth's orbit and the formation of the frigid current that flows around Antarctica contributed to the process of placing the continent in a deep freeze.

The first of the big chills came at the start of what is called the Oligocene period, around 34 million years ago, when glaciers first started to form in Antarctica.

The Gamburtsev mountains, because of their high altitude, were probably one of the places where glaciation first began, the scientists believe. At the time, there would have been a mean summer temperature of three degrees C (37 degrees F), they estimate.

The second cooling spurt came some 14 million years ago, characterized by a plunge in temperatures of around six to seven degrees C (10.8-12.6 degrees F), reaching up to eight degrees C (14.4 degrees F) in the Transantarctic Mountains, the spine that divides East from West Antarctica.

Related Links:

HowStuffWorks.com: Global Warming Works

Discovery Earth Pub

British Antarctic Survey