The hillside above Rothera is covered in crevasses, formed as the ice-sheet covering Adelaide Island splits and cracks as it grinds over the contours of the landscape. Mostly these are just considered a nuisance, a dangerous feature that can catch out the unwary polar traveller. Sometimes they are an obvious gaping chasm; more often, however, they get gradually covered over by blowing snow that forms a thin bridge. This may leave a tell-tale dip in the snowscape, or may be completely invisible. When travelling across the snow it is often impossible to completely avoid crevasses, so many of the travel techniques used by BAS in the field are designed to minimise the risk to a person or skidoo if a snow-bridge gives way.
One of the crevasses closest to the base is so easily accessible that we can skidoo up there, abseil in and get a glimpse of what it looks like under the ice. The weather has been so manky above-surface recently that a group of us, lead by Field-Assistant Steve, decided to do just that.
The crevasse itself is completely covered over with blown snow, with just a small entrance hole kept clear for access. Abseiling in is a bizarre experience – there is so much snow on the ground that only a very faint bluish light filters through from overhead. However, as soon as the head-torches go on, the whole place lights up with reflections sparkling from perfectly-formed ice crystals and stalactites.
Unexpectedly, the crevasse is not a textbook vertically-sided chasm; it is much more akin to a wandering cave-system. As the ice has twisted and buckled under the pressures over the years, it has formed chambers and passages spanning many levels, with off-shoots and dead-ends heading off in every direction. Occasionally, a new chamber will open up, sometimes even linking on to a separate crevasse system that can be visited and explored.
Despite the relative ease with which we can access the crevasse, it still holds some dangers. The polished ice underfoot is treacherous and must be navigated carefully, even when wearing crampons. Glossy steepening slides can end in vertical drops, and false-floors formed of thin sheets of ice must be trodden lightly to avoid plummeting into the depths below. You can see from the photos that we remained tied-in to ropes fixed with ice-screws, providing a measure of security against the unexpected.
It’s a beautiful place – silent, apart from the occasional creak and groan of the ice. The walls of the chambers are sculpted into waves and folds by summer meltwater, and even the gentlest brush against the wall or roof gently results in a cascade of ice crystals falling down around you.
The biggest challenge down there is photography. With no artificial light, the gloom and lack of contrast makes photos look dull and flat, but the light of a flash-gun echoes off every polished surface, turning the whole place white! Of course, practice makes perfect, so in the interests of my photography I must reluctantly submit to another trip down there as soon as possible.