Saturday, November 10, 2007

Skies are clearing and more core

The skies are clearing and the weather is improving. Two planes came in in the past 24 hours. One brought our Italian co-chief scientist and a large supply of drilling mud. The decision has been made that we will continue drilling now that it is going so well and skip geophysical logging of the hole until later: that is when logging scientists send instrumentation and a camera down the borehole to make measurements and images of the formations. We are working 12 hours a night now and are describing 30-40 meters of core per shift. We are still about 100 meters behind the drill bit which is currently sitting at 635 mbsf. Today we saw mudstones with hundreds of Serpulid worm tubes and another possible piece of plant debris. We also encountered a beautiful dropstone: a rock which fell out of an iceberg into te ocean and depressed the laminated (or layered) sediments. It is a Ferrar Dolerite clast, which is a group of igneous rocks cropping out in the Transantarctic Mountains. They form hundreds of meters thick sills (the chocolat brown layers in the photo), which are eroded by outlet glaciers feeding from the ice sheet behind the mountains. We are finding many clasts of this type in the core lately. Overall we can see the ice sheets come and go and they leave their signature in the rocks we log. It is a pretty nice job we have!

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