Seeing into the Past
Temperature -1C, wind 25 kts, 3 meter swells
At Site U1356, Hole U1356A,
Position: 63º 18.6139’S, 135º 59.9397’E
Water Depth: 4003 meters
ABOARD THE JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Here we are on the 29th of January, 20 days out of Wellington, New Zealand, and exactly 1/3 of the way through our expedition to the coast of Antarctica. It’s been a fantastic week for everyone aboard. We have now drilled over 750 meters into the seabed off of the Wilkes Land Coast of Antarctica. We are operating far enough offshore that we are in deep water – over 4,000 meters deep. This means that we have 4750 meters of drill pipe hanging from beneath the ship. The entire length of pipe rotates a drill bit and we bring up sediment cores in 10 m sections about every two hours.
The cores get run through a variety of tests on the ship. We measure how much magnetism they have and how much natural radiation they emit (all rocks and minerals on Earth emit very low levels of natural radiation). This tells us how old the cores might be. We then split them using a diamond saw (we are so deep it is real rock coming up now) and run more tests.
I am a specialist in sedimentology which means that I describe the sediment – is it mud? Sand? Does it have fossils? Are there features that tell us of past submarine landslides? The sedimentologists get to see all of the sediment cores that come up so it is very exciting. We have seen long intervals when icebergs were dropping off bits of the Antarctic continent as they floated by and melted. We’ve also seen periods when there wasn’t much ice at all.
The sediment core that just came up 10 minutes ago (photos above) contains sediments that are something like 20 to 30 million years old. We won’t know for sure until our micropaleontologists have a look but we are approaching a horizon beneath the seafloor where we expect to start seeing evidence that it was much warmer here – maybe 10 to 15 degree centigrade warmer than it is now and a time of no or little ice on Antarctica. We should be done drilling here in 2 more days. Then it’s on to the next site. I’ll keep you posted!
wow so very cool.