We finally broke free of the ice surrounding Palmer Station, leaving the ice flow yesterday around 3 p.m. heading back through the Gerlache Strait. Sadly last night was the last time we would see Antarctica. We all went to up the bridge to catch the last glimpses of icebergs, penguins, seals and land. At around 11:30 p.m. we retreated to bed to make sure that we would get enough sleep for the day of coring.
Because the ice loosened up, we were able to try to retrieve one more core on our last day of science on our Antarctic expedition. We arrived at the mouth of the Boyd Strait early this morning. We planned on launching a nine-meter Jumbo Gravity Core to penetrate the substrate. The depth at which we cored was around 88 meters below sea level. The plan was to grab sample on the continental slope. The location seemed like a great place because the Knudesen, which is a sub-bottom profiler, showed promising reflectors indicating that there was interesting sediment to be picked up. Unfortunately our luck at this core site was not very successful.
We attempted two cores at this station and both cores came up empty. The first core was thought to be unsuccessful because the mates of the ship had a hard time keeping the boat stationary. This was due to the fact that they were battling a double swell in the waves. After the Jumbo Gravity Core arrived on deck, Izzy quickly took off the cutter nose, but sadly there was no sediment in the core.
Luckily we had enough time to launch one more core at our last station. The marine techs reset the core to be launched off the back deck of the ship. The second attempt came up empty again. The second time around the general consensus was that the ocean bottom was just too hard. The core barrel hit the bottom twice, and this could be observed in the tension of the wire. On the computer screen we saw the wire tension lessen twice. Coming up empty was tough but considering the luck we have had at our last stations, we are satisfied with what he have as we head back to Punta Arenas.
Today was a relatively calm day in the Drake Passage. The ship was barely rolling and a few of us were able to stand outside in light sweaters while drinking tea or coffee. With the sun shining and land nearing us, we all felt energized and enthused to work. For most of the morning, we aided the Marine Technicians by washing and scrubbing dirty Float Coats. These neon orange survival jackets are used by anyone going outside on the deck. When our muddy cores were coming out of the sea and into the ship, everyone involved was wearing float coats, and everyone involved was getting muddy. We created an assembly line system, and scrubbed the coats as best as we could. Although this task doesn’t seem like much, the crew appreciated and welcomed any help we were willing to give.
After lunch we had a meeting to fill out customs forms. Tomorrow, we will arrive back in Punta Arenas and will begin preparations for going home. Following this meeting, Amelia Shevenell ’96 took the opportunity to give a brief, but informative, presentation on our accomplishments this cruise. With the entire crew packed into the muster station, we listened and learned the significance of our cores and their respective larger impact.
Shevenell explained how the Southern Ocean reveals its climate secrets through Antarctic margin marine sediments. One of our coring locations was in the Palmer Deep, a basin on the shelf that has a high-resolution climate record for the past 13,000 years. Although the Ocean Drilling Project (ODP) had cored here in 1998, the last 100 years of the core were missing. On this cruise, we were able to fill that void. The sediment water interface is crucial for any core, which is why Shevenell chose this as our first location. Now Shevenell can use radiocarbon dating to determine the time of ice stream retreat in this particular region.
But why is understanding past glacial flow important?
When we understand what controls glacial flow and are able to reconstruct the recession history of an Antarctic ice stream, we can better predict future ice sheet movement in our warming world, as well as discover the mechanisms that cause change - like temperature change and sea level change. During this cruise, we helped fill in portions of the retreat pattern that will ultimately complete the recessional history of this ice stream during the last glacial maximum.
We have returned to the Hill! The last couple of days of our trip have been hectic. Upon returning to Punta Arenas we had to immediately delve into sorting out our equipment and samples. Packing the container was a two day feat because we were making sure the container would be ready for the next cruise in January, which David Morgan’15 will a part of. After the first day of readying the container we attended the post cruise dinner. Here we toasted a successful cruise and thanked all the technicians that made everything possible. At the post cruise dinner everyone was in high spirits. This was the first time we were able to really enjoy each other’s company after the science portion of the cruise. The following day we finished up packing the container and moved off the Laurence M. Gould.
After the leaving the Gould and moving to a hotel, the science party had a mixture of emotions. We were leaving our home of the past three weeks, but soon returning to our respective campuses to eager friends. After moving into our hotel rooms we left and explored the city for the last time; we purchased last minute gifts for friends and dinned once more on the local cuisine. And as tradition we rubbed the toe of the statue of Magellan one last time, thanking him for a safe passage.
The return trip home took us over 36 hours to complete. We woke up at 7:00am on Sunday and arrived back on the hill at 1:30pm Monday. Looking back we traveled over 15,000 miles and were part of a once in a lifetime experience (hopefully not). Explaining our trip and showing pictures hasn’t done this opportunity its justice. We wish that everyone had the chance to experience the adventure that we just completed. Izzy and I are so fortunate to be part of this opportunity and appreciate all the help that was involved in our ability to attend. We thank Professor Eugene Domack for giving us the opportunity and believing that we could handle the cruise. And we would also like to thank our Professors who so kindly worked with us developing course plans so we could par-take in this opportunity and complete our course work simultaneously.