After many delays, Ken Sims is finally on ice—antarctic ice. He is studying the origins of ancient, frozen volcanic islands around Antarctica by analyzing their rocks. Dangers abound, but Ken is willing to brave them for science.A helicopter at the cliffs of Lewis Bay. Note the ice seracs overhead and avalanche debris below. (Photo by John Catto)
I am back in Antarctica to do what we could not do two years ago because of thin ice, and were not able to do last year because of the “partial” government shut down, which is to sample the volcanic sea cliffs of Mt. Bird at Lewis Bay on Ross Island.
This year we flew down even earlier in the austral spring to accomplish our mission. After a few delays because of bad weather, John Catto and I flew out to Lewis Bay and found that the sea ice was thick enough to land a helicopter on safely. So, we were finally able to sample the lava flows that make up these sea cliffs; the samples which my colleagues and I have now coveted for two years.
Collecting these samples was somewhat sketchy, requiring considerable caution and some luck. The transition between the sea ice and the cliffs had several melt pools and needed careful negotiation, but more concerning was the big ice fall looming overhead. This ice fall is regularly calving off and falling in avalanches over the cliffs, leaving big piles of ice debris. Getting in and out quickly was critical. Nonetheless, as luck would have it, nothing came off from overhead while we were sampling. And yes, indeed, it was cold; -24 degrees Celsius, but sunny and no wind, unlike the day before when we were out snowmobiling on Hut Point Peninsula. That day, it was -35 degrees Celsius with a constant wind speed of approximately 20 knots and gusting at approximately 35 knots!
These Lewis Bay samples are an integral part of our study to understand the origin of Ross Island’s volcanoes (Mt. Erebus, Mt. Terror and Mt. Bird) and the many small volcanic vents along Hut Point Peninsula. These samples are particularly important as they represent the oldest exposed rocks of this volcanic provenance and as such they will help us address why Ross Island is here. Is it formed by a deep mantle plume welling up, like the one that is forming the Hawaiian Islands? Or, is Ross Island here simply because the Earth’s crust is ripping apart along the West Antarctic Rift, like the volcanoes in the East African Rift?
Using these samples, samples we collected two years ago, and samples we will collect over the next couple of weeks, we are using complex geochemical measurements of radiogenic isotopes (little clocks in the rocks) to resolve this long-debated question. So, stay tuned…