Yesterday my fellow writers (James and Alice) and I went on an amazing helicopter trip to Cape Evans (to see Scott’s Hutt), to Cape Royds (to see Shackleton’s Hut and the Adelie penguin colony) and to Lake Hoare in the Taylor Valley to visit an American field camp. Then last night I had the unique privilege of being a judge of Miss Ross Island 2011 (skirts man-datory). But one of the highlights of this remarkable day was going out onto the ice and doing just the tiniest bit of fieldwork with a couple of the scientists here.
It’s not all cross-dressing skirt parties, Hagglund racing and helicopter rides around here. Most of the people in Antarctica are here to do science or to support science. The helicopters, fixed wing aircraft and Hagglunds are here to transport scientists to their field camps and the logistical staff, field staff and technical staff are here to support the science programmes.
So, after dinner last night, Alice and I went out onto the sea ice with Nick Golledge from Victoria University of Wellington and Oliver Marsh from the University of Canterbury. Scott Base is built close to the southernmost point of Ross Island. But instead of sea lapping at the shore, there is sea ice, which is typically about two feet thick. A few kilometres further southeast the sea ice meets the Ross Ice Shelf, a slab of floating ice about the size of France.
The Ross Ice Shelf is really a huge glacier, the seaward junction of both the West Antarctic Ice Sheet and the East Antarctic Ice Sheet. As the Ross Ice Shelf moves forward, it pushes the sea ice forward too. Where this forward moving sea ice pushes against the sea ice formed around Ross Island, it’s like two tectonic plates pushing against each other, and the movement of the two slabs of ice against each other forms a series of pressure ridges. The first sign of the pressure ridges are a series of gentle hills and valleys, but as the pressure increases the ice breaks. At the tops of the ridges, the broken ice forms sharp peaks and cliffs, all at the scale of a few metres, and all in ice coloured a range of shades from white to blue. Along the valleys between the ridges, seawater flows up through the cracks and rifts and freezes into flat blue ponds. Weddell seals take advantage of the thinned ice – they gnaw their way through the sea ice and lurch up onto the ice where they seem to lie immobile for days. This makes the pressure ridges a beautiful, but also dangerous, place to walk. The ice is constantly moving and it changes every day. New cracks appear. New ponds form. Occasionally a seal moves. The field staff here walk around the pressure ridges twice a week, drilling holes to test the ice thickness, and marking the danger spots with black flags and the safe routes with green or red flags.
Even so, if we want to walk around the pressure ridges we must first don appropriate cold weather clothing (a layer of polypropylene then salopettes, Sorel boots, down jacket, hats, neck gaiter, gloves, sunglasses, etc), sign out from Scott Base, take a radio and a long wooden pole to test the ice ahead (Stu calls it a “seal club” so I guess it has a dual purpose), and radio in as soon as we are on the sea ice.
Last night, we met at the Hillary Field Centre – the part of Scott Base where all the technical equipment is kept and from where expeditions leave – and helped Nick and Oli with their gear. Alice carried a large metal pole and I carried the top of the GPS receiver in a yellow bag. Nick and Oli carried a 30kg battery between them. This was actually quite helpful of us, I would like to point out, since without our help they would have had to put all their gear on a sled and tow it out, which can be awkward, given all the ups and downs of the path. So we were a very important part of the mission.
We radioed into base as soon as we were on the sea ice, then, on the near side of a large pressure ridge, Alice shoved the pole deep into the ice, I screwed the flat round top of the GPS receiver on, and Nick and Oli attached the battery and made sure everything was working. Their plan was to leave the GPS receiver out overnight and check the readings the next day. Across the other side of the pressure ridge, they had already set up another GPS receiver, this one solar powered, which was also gathering data. When they compared the readings from each site they would have an indication of how far the sea ice was being pushed forward every day. Nick says it can be more than a metre a day.
Anyway, this did make me feel very pleased to be actually “doing some science” but for Nick and Oli, this evening excursion was just a test. Before they leave Scott Base to do their fieldwork, they are testing all their equipment. Next week, they are going to install 10 GPS receivers on a longitudinal transect (I talk like that now I’m a field assistant) down the Skelton Glacier to measure the latitudinal, longitudinal and tidal movement of the glacier ice over a one-month period as part of the ANDRILL project. But that’s another story.