Friday, October 26, 2007

The biggest clast contest

Last night we described another 27 meters of core down to 198 meters below the seafloor. We are seeing large rocks (clasts), such as the migmatite in the photograph. These rock clasts have been eroded from the basement of the Trantantarctic Mountains. Antarctica was involved in a number of tectonic plate collisions and was once the center of Gondwanaland. Antarctica is for 98% covered by ice, so the igneous and metamorphic rocks we find in our cores are important in telling that story. Last night we found a granite clast of 28 cm in cross section and we have started a "biggest clast contest". We all put in our entries, and they range from 29 cm to 5 m. I entered 38 cm. Do you think it will be enough? We will see what we will find in the journey towards 1000 meters of core!

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