March 4, 2008

The winds have slowed to 20 knots, but as you can probably guess, the seas
are still to rough to core. We have been able to start trawling. Our
first trawl here in Marguerite Bay caught more rocks than animals.
Looking at the variety of rocks made us start to think about the geology
and origin of the region, so we investigated a reference book on board:






Encyclopedia of the Antarctica and the Southern Oceans. 2002. B.
Stonehouse, Editor. John Wiley ands sons Ltd. West Sussex, England. Pp.
115-117.

In the entry called “Geology: stratigraphy and structure”, we found the
info for which we were looking.

“The rocks that form the Antarctic Peninsula were deposited as muds and
fine sediments in a seabed trough from the late Paleozoic to the early
Mesozoic. They were later metamorphosed by volcanic eruptions and
intrusions. Later, folding and block faulting shaped the peninsula into
the feature we see now.”

How funny that the rocks started in the sea and are being returned by the
ice. It picks them up over land, rafts over the sea, melts and drops the
rocks onto the seabed in the process. The rocks have rough edges and are
quite colorful. We’ve found feldspar granites, shale, and sandstone so
far.




In the same entry of the book we learned a few other fun facts:

Between 590-505 million years ago (Ma), Gondwana straddled the equator,
and the Antarctic Peninsula actually jutted into the Northern hemisphere.
Between 480 and 97 million years ago, Gondwana migrated south over the
South Pole and then northward again. By 85 million years ago,
Gondwanaland was breaking apart into the continents. At the time
Antarctica was heavily forested. Up until about 60 Ma Antarctica retained
its land links with South America and Australia, so it was also home to
some of the earliest mammals. Antarctica became glaciated again during
the Pleistocene.

Position: 68 degrees 08.783 minutes South; 71 degrees 3.324 minutes West
Heading: 301.7 degrees
Speed over ground: 0.4 knots
Air temp. 3.1 degrees C; Water temp. 0.634 degrees C