Cape Roberts Project
Wednesday, 24 November 1999
This week we have had snow and more snow.
Everyone is amazed at how much snow we are getting. It is quite
unusual. However, being such dry snow, it blows away rather
quickly. Last night it snowed all night long and everything was
white when I awoke this morning. It was beautiful. And the
temperature was only +10°F. I really enjoy the snow here. It is
too dry to make snowballs or snowmen or anything, but it's fun
nonetheless.
The scientists here are nicknamed beekers,
and the only street sign in town runs in front of the Crary Lab
and is called 'Beeker St.' The beekers I have gotten to know the
best are involved in a very exciting project called the
Cape Roberts Project. This project's aim is to recover and analyze
core samples from the sedimentary strata beneath the sea floor
off of Cape Roberts in the Ross Sea. Some of the things they
hope to find out are how far back in time ice sheets on the
Antarctic continent have been causing changes in global sea
level; weather patterns during those times which will help
enable future global weather predictions; to date the rifting
of the Antarctic continent in order to understand the formation
of the Transantarctic mountains and the Ross Sea.
Millions of years ago Antarctica was part of
a larger land mass called Gondwana, which was made up of what
is now South America, Africa, India, Antarctica, and Australia.
About 470 million years ago Antarctica was actually near the
equator and was covered with plants and animals. We have an
abundance of fossil evidence to support this. By 280 million
years ago Antarctica had slid southwards and was over the South
Pole. A major ice age occurred on all these southern
continents. 160 million years ago was a warm period with no
polar ice caps. Antarctica had shifted away from the South Pole
as a prelude to the break–up of Gondwana. By 70 million years
ago Antarctica had moved back close to the South Pole and wide
oceans developed between Antarctica and Africa and India. 45
million years ago Antarctica continued to shift towards the
South Pole and became surrounded by oceans as Australia headed
north. The encircling oceans isolated Antarctica and gradually
cooled it.
By drilling into the earth the scientists
can go back in time to learn about earth's history. However,
finding drilling equipment to go deeper and deeper gets more
and more difficult and vastly more expensive. Fortunately they
have found a place at Cape Roberts where strata are curved in
an upward slope because of the formation of the Transantarctic
mountains. In other words, the strata recording old glacial and
rifting events are at or near the surface. Elsewhere they are
quite deeply buried. This allows them to go back further in
time, but without having to drill so deeply (relatively
speaking of course).
Because this strata is located
under the Ross Sea, a drill rig has to be constructed on top of
the sea ice. This drill rig weighs 57 tons, and the drilling
equipment itself weighs another 9 tons. The drill has floats
attached to it to help support the weight, and huge balloons are
inflated under the sea ice to help support the rig, adding an
additional 11 tons of lift. Of course timing is critical.
Drilling cannot begin until early spring (October–November) to
allow the sea ice to thicken to at least 1.5m to be able to
support the rig. This particular sea ice is not part of the
permanent ice shelf and will be melting away rather soon, some
time in December.
The water beneath the ice ranges from 150 to
400 meters deep. Measurements and adjustments must be made
several times a day. A small camp of around 40 support and
science people is set up at the drill site and crews work around
the clock on 12 hour shifts. Core is brought to the surface
after each 3m of drilling.
Cape Roberts photos courtesy of McMurdo Station's I-drive
During the first drilling
season they drilled 148m below the sea floor. Diverse shells
found at 32 meters below the sea floor and 1.2 million years old
indicate conditions for a brief period very different from
today. Layers below 43 meters under the sea floor and 17 to 22
million years old indicate a warmer but highly variable style of
glaciation and many new microfossil species to help dating in
the future.
Cape Roberts photos courtesy of McMurdo Station's I-drive
The hope for this season was
to drill to a depth of 700 meters below the sea floor. They have
had an absolutely exceptional season and have surpassed their
goal by going to a depth of 938.42 meters. Everyone is very
excited. It is the deepest bedrock hole in Antarctica. It will
be some time before all of the data is analyzed and reports
made, but preliminary estimates are that these core samples are
around 350 million years old. It is really amazing. Once the
cores are brought to the surface the outside is scanned into the
computer, and at the same time a camera inserted into the hole
photographs the corresponding section remaining in the earth.
Electromagnetic measurements are also made. The core is then
transported by helicopter from the drill site to the Crary Lab
in McMurdo. There it is sliced in half lengthwise.
One half will be put into cold storage and saved
as an archive. This is stored at Florida State University in
Tallahassee. The other half of the core is available to the
various scientists. As soon as core is brought into the lab the
scientists all gather and select sections they are interested in
studying. The sections are really quite small, ranging from 1 to
3 cubic centimeters. These are then cut out and set aside for
the scientists. The remaining section of core is put in cold
storage in Germany, and is available for the scientists at
future times if need be.
I have spent a good deal of
time in the lab and I have to tell you that seeing some of these
fossils and this rock from nearly 1000 meters under the earth
that is 350 million years old is awe inspiring for me. I know
that you can go out in many mountains and other places and find
rocks much older than that, but somehow seeing this rock that
has been under the earth for all those millions of years is
amazing. The core also has a smell all its own as well. I
would not know how to describe it other than earthy. It is nothing
I have smelled before and not at all unpleasant. I have also seen
many of the fossils they have found. It is a wonderful
experience.
The Cape Roberts Project is a
joint venture by scientists and the national Antarctic programs
of Australia, Germany, Italy, New Zealand, the United Kingdom
and the United States of America. Dr. Peter Webb started this
project. He first came to Antarctica as a student in 1957 and
has been coming ever since to work on various projects. He is a
very interesting and nice man.
John Wrenn is a palynologist from Baton
Rouge, LA. He studies the fossils in the core and helps to date
the core. He and Matt Curren are my good friends and wonderful
people. Matt is the assistant curator of the core and lives and
works in Tallahassee at Florida State University. Pictured below
are some of the fossils they have found.
Fossil photos courtesy of McMurdo Station's I-drive
If you would like to read about some of the results from these
experiments, try these links:
Cape Roberts Project archive
Cape Roberts Project
Cape Roberts Antarctic Photo Gallery
NASA news
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