Land Geology

Geology is done under the watchful eye of the local inhabitants. Photo: Yani Najman

By Yani Najman | It has long been my dream to work in the Antarctic, both because of its fabled beauty and remoteness, and because of the special importance it has on our planet’s changing climate; if the West Antarctic Ice sheet were to melt, predictions suggest a rise in global sea level of 3-5m. One doesn’t need great imagination to consider even the most obvious consequences; how many of our major cities are located not far above sea level?

I finally got my chance to work in Antarctica, as part of Conny Spiegel and Max Zundel’s research team. They are from Bremen University, and were joining the multi-Institute expedition led by AWI (the Alfred Wegener Institute), with Chief Scientist Karsten Gohl. The plan was to take the German Research Vessel “Polarstern” (Polar Star), an icebreaker, from the southernmost tip of South America, to work in the Amundsen Sea of West Antarctica. This region of Antarctica is important for understanding the causes and effects of climate change. Firstly, although the West Antarctic Ice sheet is much smaller than the East Antarctic Ice sheet, it is more likely to melt. This is because whilst the base of the East Antarctic Ice sheet lies on rock above sea level, the base of the West Antarctic Ice sheet lies on substrate below sea level, and so it can be melted from below by relatively warm ocean waters. Secondly, glaciers in this region have shown high rates of retreat in the past decades. But no-one knows the extent to which these retreat rates are part of a longer term pattern of change that has been ongoing since Earth began to warm up after its last cold period (called the Last Glacial Maximum), 18,000 thousand years ago, or if it has been triggered by more recent changes in our climate and oceans. And so more than 40 scientists set out on Expedition PS104 on 8^th February, to try to answer this question.

The “Star of the Show” is MeBo, which is a revolutionary coring device that allows us to collect sediments up to 70 m below the sea floor. These sediments will provide a record of the past movements of the glaciers which debouch into the Amundsen Sea, and of past sea water temperatures. However, I’m part of the team which gets helicoptered from the boat to work on the land each day. We have two objectives. Firstly, we are to collect rock samples for “exposure dating”. An exposure age is the date that a rock became uncovered (“exposed”) from beneath the ice. So by collecting samples at many locations, we can track the pace of retreat of the glacier. Our second job is to collect rocks which we will date to determine how many millions of years ago they cooled, as they came from deep in the earth’s crust, towards the cold surface. And from this we can work out the time the land rose up, which is a necessary precondition for glaciers to form on it. In this way, we can date when glaciation may have begun in the region.

And so after a “typical” rough crossing of the Drake Passage, a beautiful transit through iceberg-haunted waters, a thorough practicing of our snow and ice rope-rescue skills on deck, and a double-checking of our kit, we began the anxious wait for the “weather window” that would allow the helicopter to take us to land for the first time. Finally the green light, and with much anticipation I fought my way into my survival suit and waddled off like a Michelin-man to strap into the heli. The flight was so beautiful as we soared over the endless ice. I was mesmerised. But the first attempt at landing ended in disappointment – we circled the cliff, but even though it was so close it felt like we could reach out and touch it, Martin the pilot did not find conditions suitable to land, and we returned to the ship empty-handed.

Success awaited us on the second attempt however. I don’t think I’ll ever forget the moment the heli skids touched down, and I realised I was finally on land in Antarctica. My dream come true. It was overwhelming. I hardly noticed the piercing wind as I drank in the sights of penguins, and seals, and icebergs. Then the sound of the heli-rotors bit into the silence, and as the heli disappeared into the distance, I had a moment of trepidation; we were truly truly alone, tethered to the Polarstern only by a satellite phone (that we had to call on every hour), and with an extremely comprehensive emergency kit. But the moment passed quickly. Max, the more seasoned Antarctic geologist, brought my focus quickly to the work at hand, and soon I was lost in the familiar routine of field work.

And so to success? We have three more weeks of the expedition and as is normal in Antarctica, the conditions, not the scientists, have the final say in the degree of our success or failure. Will the MeBo corer succeed in reaching 70m depth? If an iceberg’s movement trajectory suggests it’s heading our way, we will have no choice but to pull up MeBo from the sea bed and leave the site, rather than risk a collision. Meanwhile, our “Land Geology” team have succeeded in collecting enough rocks to track the retreat of the glacier with time. But will we also succeed in collecting the rocks we need to determine when the land rose up, and glaciation could have commenced? These rocks lie at a site to the west of our current location that, as I write, lies tantalisingly close, yet just out of helicopter range. Whether the ship turns east, away from our target area, or west, towards it, depends on the sea ice conditions, and the movement of the icebergs, “our large white friends” as our Chief Scientist calls these constant companions of ours, the determinators of our scientific fate.

By Yani Najman (Lancaster University)