Beacon Valley Debris-Covered Ice
Buried ice deposits represent a new and potentially far-reaching
archive of atmosphere and climate on Earth extending back for
many millions of years. These deposits may be a terrestrial analog
to widespread and young buried ice on the Martian surface as identified
by recent data from Mars Odyssey. David Marchant and his group
from Boston University now ask whether ancient, debris-covered
glaciers in the Dry Valleys region, Antarctica, hold similar records
of temperature and atmospheric change to those in the deep ice
cores of the Antarctica and Greenland ice sheets, but on time
scales that are perhaps an order of magnitude greater.
They propose to evaluate the age, origin, and climatic significance
of buried ice in the western Dry Valleys. They and others have
published evidence that the ice to be examined is over a million
years old; if true, that would make it the oldest ice yet known
on this planet. An alternative view is that the buried ice is
more recent segregation ice from the in situ freezing of groundwater.
Distinguishing between these hypotheses is key to understanding
Neogene climate change in Antarctica.
In the 2004-05 field season, ICDS will aid Marchant to drill
a series of cores from the head of Mullins Valley Glacier (pure
glacier ice) to near the toe of the glacier -near where it extends
out onto the floor of upper Beacon Valley. The concentration of
isolated rocks and debris in the ice increases down valley and
it may present a serious obstacle to drilling, but our hope is
that with a motorized "Sidewinder" drill and many replacement
cutting heads we can drill past the occasional rock and continue
downward through the ice to ~20 m depth. Also, we should learn
more about the debris content in these glaciers (amount, spatial
distribution, etc), which would then help us determine the precise
needs for a dedicated "dirty-ice drill" that we hope to develop,
with which to penetrate ice with greater debris content during
the 2006-07 field season.
For a story on Marchant's work go to: http://www.bu.edu/alumni/bostonia/2000/winter/antarctic/index.html
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