Geoscience Reference
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Alternatively, and a more exciting possibility, they may represent a volcanic
uplands currently or recently active that sits above an anomalously hot part of
the Earth
'
s interior or close to a previously unrecognised boundary between two
portions of the Earth
s outer crust, known as tectonic plates, that have moved
relative to each other. The presence of such a large hidden highland region is in
marked contrast to West Antarctica where much of the landscape is below sea
level with the Byrd Subglacial Basin and the sinuous Bentley Subglacial Trough
plummeting down to 2000m below sea level, that is, after we take the weight of
the Antarctic ice sheet into account. If the ice sheets were to melt much of West
Antarctica would be
'
ooded by seawater.
Although the ice sheets are, for the most part, sitting on and moving slowly
across a rocky substrate we now know that more than 300 lakes exist beneath the
ice sheets. The largest and most well known is Lake Vostok that sits in a depression
close to the subglacial Gamburtsev Mountains. It is approximately 250 km long,
50 km wide at its widest point and has an average depth of 344m. Some of the lakes
are apparently connected by sub-ice channels whereas others remain isolated.
The subglacial lakes have to this day remained unexplored although scientists are
keen to probe the hidden depths of the lakes and test the widely held view that life
exists in what is predicted to be an unusual geochemical environment.
Figure 2.9
Gamburtsev Mountains. A three-dimensional image constructed from
radio-echosounding data. (Credit: Michael Studinger)
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