Wednesday 31st October
The aim of this research is to investigate ice-shelf processes, Holocene glacier dynamics and rates and magnitudes of glacier thinning following the Last Glacial Maximum on Alexander Island. Alexander Island is particularly interesting, as is it is joined to the spine of the Antarctic Peninsula mountains (Palmer Land) by George VI Ice Shelf. The coastline of Alexander Island is therefore characterised by ice-shelf moraines, formed by the floating ice shelf abutting the land.
We will be visiting a part of Alexander Island called Ablation Point Massif, which is particularly famous for these ice-shelf moraines and its record of glaciation from the Last Glacial Maximum and through the Holocene. Ancient ice-shelf moraines are reported at elevations of 82 m (the current height of the moraines being 5-10 m). These moraines are undated, but the presence of boulders of Palmer Land granite within them mean that they may be possible to date using cosmogenic nuclide exposure age dating. The height of these moraines means that they could be quite old, with a Holocene sea level high-stand occurring in the area at about 5000 years ago at ~15 m. This area was part of the onset zone for the Marguerite Bay Ice Stream, but the dynamics of the ice are poorly understood. Understanding the situation, age and processes of deposition of these granite erratic boulders is crucial to understanding the dynamics of the last Antarctic Peninsula Ice Sheet in this area.
With this rationale in mind, Mike Hambrey and myself have travelled from the UK to Rothera (via Sao Paolo, Santiago and Punto Areanas) and have just arrived on the Dash-7 airplane. It was a spectacular flight in, with beautiful scenery as we approached Rothera.
Upon arrival, we were given lunch (I always want to know where my next meal is coming from!) before receiving a tour of the base. We were then treated to a tour around the Point, a beautiful and scenic ½ hour walk around Rothera. Rothera operates a sign-out system, so you have lots of freedom as long as you tell people where you’re going and when you’ll be back! Today, we also met Ian Hey, our field assistant, a technical mountaineering expert who will assist us with the science in the field, while making sure we remain safe and well and keep out of glacier crevasses!
The temperatures around Rothera are about -10°C maximum during the day, and it is starting to remain light until very late at night – already there is no real dark here, at 67°South. In just a couple of months we will have the longest day, and near 24-hour sunlight. There is tonnes of snow everywhere, with piles around the buildings up to roof level in parts. The sea is completely frozen and there is no wildlife here yet. The base was only opened for summer with the first Dash-7 rotation a couple of weeks ago, and there are still relatively few people on base. However, I believe that the winterers are pleased to see a few fresh faces around!
Our field site, Ablation Point Massif, is an Antarctic Specially Protected Area (ASPA) due to its mosses and its geomorphological interest, with unusual ice-shelf moraines. We therefore needed to obtain permits from the Foreign and Commonwealth Office before fieldwork commenced. We also had to minimise our environmental impact on the area. It is a vehicle-free zone (so no skidoos are allowed) and planes cannot land on the frozen Ablation Lake. Not using skidoos has the added advantage of making logistics simple; all our science and survival kit can fit into one Twin Otter payload. We therefore will land a Twin Otter on the ice shelf as near as we can, but beyond the pressure ridges that build up as the ice shelf impinges on the land. We will need to man-haul all our survival and science kit on sledges through the ice pressure ridges, before we can make camp among on the moraines near Moutonnée Point.