continues on p. 61 46 OregonStater.org degrees Fahrenheit. Life in high winds is difficult: visibility is obscured, walking outside requires determined effort, and you must yell to be heard inside the flapping tents. “YOU’RE GOING to do it tonight, I am sure of it,” said Ivo at dinner on Dec. 23 when the night shift was suiting up. The first shift had stopped drilling just shy of 324 meters — the equivalent of an 80-story building, over three Statues of Liberty long.“You are going to go in there, drill 3 meters and hit bedrock!” I hoped he was right. Feeling less optimistic than the night before, we set up for another drilling shift. The drill had some trouble cutting through the ice at first, retrieving only 11 centimeters of ice.Andrew and Dusty changed the cutters on the drill and tried again. This time, the core successfully pulled up a full meter, after a long struggle caused by cutting through a rock. The core had some very deep micro cracks, so thin that you might miss them if you didn’t know what you were looking for. Such cracks cause the air bubbles to leak and gases within the core to mix together, rendering them useless as pristine air samples from specific moments in time.The appearance of micro cracks usually indicated that we needed to add more fluid to the borehole to counteract the pressure at deeper depths.The fluid column was now about 110 meters deep. Andrew frowned at the cracks and asked, “How valuable is the ice at the bottom of this core?”An and I looked at each other. “Well … ,” she said, “the ice at the bottom is usually the oldest, so pretty important.” Andrew gamely went out into the howling winds to get another 55-gallon barrel of Estisol and pump the fluid into the borehole. It was after 11 p.m. when the next core came up, and it was only half a meter. The work was feeling especially slow and discouraging. Each drill run What is COLDEX? COLDEX — or Center for Oldest Ice Exploration — is a multi- institutional NSF Science and Technology Center headquartered at Oregon State University. Are we the only ones trying to find the world’s oldest ice? Several groups have taken up the challenge, including consortiums of European, Australian and Japanese researchers. How do you keep the ice from melting? Each night, cores are transported back to camp on a sled attached to a snowmobile and stored in a trench dug into the ice. About once a week during the field season, small planes come to the Allan Hills to fly cores to McMurdo CORE QUESTIONS Station, where they are stored in a refrigerated shipping container until they can be loaded onto a cargo vessel. The ship takes them to California, and from there they are transported by truck. Where do you keep the cores? The cores are stored at the NSF Ice Core Facility in Denver. Teams of COLDEX scientists cut off samples and ship them to laboratories at Oregon State University, Princeton University, University of Washington and others for different kinds of analyses. How can you tell how old the ice is? In the lab, COLDEX scientists determine the age of the ice by analyzing argon gas isotopes trapped in its bubbles. How old is the oldest ice drilled at the Allan Hills? The previous season COLDEX drilled ice cores older than 6 million years old. Although we don’t think this ice core will be that old, we know from other cores in this location that we should have ice that’s 1 to 3 million years old and very high quality. Why does that matter? The oldest ice from other ice drilling projects (Europe’s Beyond EPICA-Oldest Ice Project) only goes back to 1.2 million years. With COLDEX’s ice cores, we can directly sample much older air, which no one has ever been able to do before. Looking into the borehole, you can see just how blue the ice really is. The blue color is the result of millions of years of compression.
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