Podcast episode 2 - Published 06 July, 2017 by Nicholas O'Flaherty
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In our podcast this week, we speak to Professor Robin Bell, a geo-physicist at the Lamont- Doherty Earth Observatory of Columbia University, New York. Robin Bell led a major multi-national expedition to Antarctica in 2008, the Antarctic Gamburtsev Province Project (AGAP), to explore the Gamburtsev Mountain range.
The Gamburtsev Mountains in Antarctica are the size of the European Alps. But no human being has ever laid eyes on them - because they are totally buried beneath the mighty East Antarctic ice sheet, 600m in some places, but more than 1 kilometer in others.
They are sub-glacial mountains, mountains beneath the ice; their highest point is 2700m above sea level – yet not one single craggy peak sticks up above the ice sheet. The Gamburtsevs are the highest sub-glacial mountains in Antarctica, and the world.
They’re sub-glacial, because where they’re located, beneath the center of the East Antarctic ice sheet, the surface of the polar plateau reaches up to 4000m in altitude at its highest point, Dome A.
The invisible mountain range was first detected in 1958 by the Soviet Antarctic Expedition, during their ground-breaking traverse from the Antarctic coast to the high polar plateau.
Like other expeditions during that International Geophysical Year, the Russian scientists used oil industry technology to try to get a measure of the thickness of the ice sheet beneath their feet. Every 80km or so, they drilled 40m holes and lay geophones, sensitive recording devices, into the ice sheet. Then they would set off a small explosive charge. The return echo bouncing off the bedrock below, would be recorded by the geophone, giving a measure of the thickness of the ice sheet at that particular point.
The thinking had been, that Antarctic bedrock must resemble the glaciated landscape of other parts of the world that had experienced massive ice sheets in the past. Think for example, of much of Canada today, which sat for thousands of the years beneath the Laurentide Ice Sheet during the last ice age.
However, what the Russians found in East Antarctica, surprised them. The returning echos revealed the sketchy outline of a mountainous range encased within the ice. In honor of the leading Russian seismologist Grigory Aleksandrovich Gamburtsev who had died in 1955, the Soviets named the newly discovered range, the Gamburtsev Mountains.
Since then, our knowledge of the Gamburtsev Mountains increased significantly with the Antarctic Gamburtsev Province Project (AGAP) of 2008-2009, in which Professor Robin Bell played a major role. The findings of that mulit-disciplined project were a huge leap forward in our understanding of this important yet previously little-known region of Antarctica. Antarctica’s largest sub-glacial lake, Lake Vostok, lies within its foothills. Today, scientists believe the Gamburtsev mountains were one of the key nucleation points around which the Antarctic ice sheet first started to expand more than 30 million years ago.
More information on the Antarctic Gamburtsev Province Project (AGAP) of the 2007-2008 International Polar Year can be found at:
http://www.ldeo.columbia.edu/res/pi/gambit/
http://nas-sites.org/us-ipy/the-gamburtsev-mountains/
In this podcast, Professor Bell also talks about the ROSETTA Project, which will commence its third field season in Antarctica later this year, with aerial and ocean-based surveys of the Ross Ice Shelf.
The ROSETTA research program aims to conduct a detailed survey of the Ross Ice Shelf, primarily through flying back and forth over the ice shelf in a LC-130 aircraft to create a grid of the information collected. The LC-130 is equipped with an “IcePod”, which contains various scientific instruments to collect aerial measurements and create a detailed map of both the ice shelf and the sea bed below it.
The IcePod collects a range of information, including ice surface elevation (using LiDAR), ice thickness (using radar), and the shape and materials of the ocean floor beneath the ice shelf (using gravity and magnetic measurements).
As well as aerial surveying, the ROSETTA researchers also use six “Alamo drifters”, floating units deployed into the ocean in order to collect data on ocean circulation along the front of the ice shelf. Matching this circulation data with the grid map created by aerial surveying will help to improve scientific models of how increasing sea temperatures can lead to additional melting of the ice shelf.
For more information go to the ROSETTA Project
Feature image: British Antarctic Survey