Gearing Up for Our First Cores
Read Sidney Hemming’s first post to learn more about the goals of her two-month research cruise off southern Africa and its focus on the Agulhas Current and collecting climate records for the past 5 million years.
Our first day on the ocean was pretty rough. We left the harbor in Mauritius into high winds and choppy seas, and I don’t think I was alone in feeling pretty miserable. I woke up the next day to calm seas and a much better perspective.
We have been busy with meetings, training sessions, and planning for the core flow, and I think people are getting close to being ready for the 12-hour shifts. My shift is 3 p.m. to 3 a.m., and my co-chief scientist Ian Hall’s is the opposite. It works out pretty well relative to our home clocks (when I start my shift, it’s 8 a.m. back in New York), and we’ll have significant overlap. I plan to get started by noon, and Ian will hang around until 6 or so before going to bed. We have decided we’ll take a break for exercise—should be a good strategy.
The staff is wonderful on the ship. They feed me great meals, and there is even an espresso machine right outside the science office where I sit. Today Kevin Grieger, our operations manager, gave us a tour to the bridge, the drilling rig and the core shack, where we met Bubba Attryde, who has been the core specialist since Glomar Challenger days and continues to make innovations. We went down through the motors and pumps, past the moon pool, and out to the JOIDES Resolution‘s helideck.
The helideck has a special role this cruise. On March 26, Ian Hall and Steve Barker will be running in the IAAF/Cardiff University World Half Marathon Championships. It requires 328 laps around the deck, which is noisy and hot. They are doing it to raise money for a small South African charity called the Goedgedacht Trust, which promotes education to help poor rural African children escape grinding poverty. Ian has learned that the money raised will help bring solar power to schools. When we reach Cape Town, some of the children plan to tour the ship.
It is now official that we will start with the Natal Valley site while we wait for clearance from Mozambique to work on what would have been our first site.
The Natal Valley is at the beginning of the Agulhas Current, where the waters flowing through the Mozambique Channel and the East Madagascar Current come together and flow along the southern Africa coast. A central goal of the expedition is to understand the history of the Agulhas Current and its role in climate variability, and this site could help us characterize how the microorganisms and the land-derived sediments it carries have changed over the last 5 million years.
Recently published evidence from the past 270,000 years from very close to the Natal Valley site also shows that there have been significant changes in rainfall in southern Africa on millennial time scales. We are very interested in getting a longer record of rainfall changes with this expedition. So in effect, we have the dual goals of understanding the nearby climate record from Africa and understanding the ocean currents below which the core is located—both the Agulhas Current and deep water circulation, which currently flows north along the western Natal Valley and is the reason for the sediment “contourite” accumulation that we are coring.
We will be getting to the Natal Valley site about 8 p.m. local time on Tuesday, so we should have cores coming in before daylight on Wednesday. You can feel the excitement start to build. Our staff scientist, Leah, has organized everybody well. The groups gave reports on their methods this morning and will turn in drafts of their methods before we get to the first site. It’s getting close!
Sidney Hemming is a geochemist and professor of Earth and Environmental Sciences atLamont-Doherty Earth Observatory. She uses the records in sediments and sedimentary rocks to document aspects of Earth’s history.