For First-Timer, an Icy Challenge
By JEFF VERVOORT
Jeff Vervoort, left, an associate professor in radiogenic isotope geochemistry at Washington State University, and John Goodge, a professor of geological sciences at the University of Minnesota-Duluth, will be writing occasional posts from their research expedition in Antarctica.
It is probably impossible to prepare yourself before getting here for what to expect from this large ice-covered continent at the bottom of the world. Like many other people, I have seen pictures and videos of Antarctica. I am also familiar with different scientific aspects of Antarctica’s oceans, climate and geology, and I had talked about this trip extensively with John Goodge, the leader of the current expedition, before coming down here. But nothing completely prepares you for this place.
It is the scale of everything here that overwhelms you — the massive ice sheets, the ice-carved terrain, the sea and shelf ice, the mountains, the weather and even the scale of infrastructure in place to support human activities. I have spent many summers in Alaska and have been throughout the mountains of the western United States and on several other continents as well. All of these places are impressive in their own way, but nothing matches the scale of what you see in Antarctica. This is an awe-inspiring place.
I have been working on projects with John over the past few years. My expertise in this work is in applying radiogenic isotopes both to determine the ages of rocks and also as isotopic fingerprints that provide clues about the origin of these rocks. All of this work with John has related one way or another to Antarctica. So when John asked me early this year to join his field party in the Transantarctic Mountains, I said yes with little hesitation.
The scale and extremes of Antarctica provide enormous challenges to scientific research (in our case “doing geology”) down here. First, a vast majority of the continent — and all of the older part of Antarctica we are trying to understand — is covered by immense ice sheets and is inaccessible to direct sampling. Second, our field sites are hundreds of miles from the nearest fixed base. All access from McMurdo is by helicopter, plane or (when at one of our remote sites) snowmobile. This requires enormous infrastructure to enable us to get to our remote camps and to move us to the different locations where we will do our research. And third, once in the field the extreme environmental conditions make doing hands-on work challenging, to say the least.
Our approach in addressing the first challenge — trying to understand what is buried under thousands of feet of ice at the core of the Antarctic continent — is to sample rocks eroded and carried along by the enormous ice sheets that cover a majority of it. These ice sheets flow into, around and over the peaks of the Transantarctic Mountains on their way to the sea. Where they do so, there are places where loss of ice from the glaciers (mostly by sublimation enabled by abundant sunshine and persistent winds coming off the polar plateau) outpaces growth of new ice. In places where this process is extreme, the rocks carried by the glaciers may be exposed at the surface in bare “blue ice” or left in glacial deposits known as moraines.
The challenge is to find areas where, first, this process occurs, and second, where the long-carried glacial material can be distinguished from the material derived locally from the rocks of the Transantarctic Mountains. In this way, our job is similar to that of the groups that each year scour the blue ice near the edge of the polar plateau looking for meteorites. But instead of looking for material that has landed on top of the ice cap and been carried for great distances, we are looking for material sourced from below, scoured by the base of the ice sheet.
John and his colleagues took this approach a few years ago in the central Transantarctic Mountains. Now we are attempting to extend our sampling along a greater length (over 1,500 kilometers) of the Transantarctic Mountains to obtain a larger view of the buried Antarctic continent. Our attempts this week working in the northern part of the mountains have not yet been terribly successful. We had identified several attractive targets by satellite imagery and existing maps to the northwest and southwest of McMurdo. The clasts, or fragments, at these sites, however, have proved to be locally derived, and very few of the clasts appear to be from the older (“basement”) part of the Antarctic continent, which we are most interested in.
Further trips to look at more sites within a day’s reach of McMurdo have been thwarted by bad weather and cancellation of planned helicopter trips. Now our efforts will be directed southward in the area around 85 degrees south. The United States Antarctic Program has established a seasonal base camp (CTAM, for Central Transantarctic Mountains) near the Beardmore Glacier and near the edge of the polar plateau. We will be setting out two remote tent camps north and south of CTAM. With luck, our next post will be from CTAM after getting firsthand experience with the next challenge of work in Antarctica — transportation — and the impressive infrastructure in place to meet that challenge.
I did get a good taste of doing field work in Antarctica on our last two helicopter trips. Both trips took us over astonishing terrain and into some extraordinary field sites. Both days on the ground were filled, on the one hand, with wonderment about and awe of the physical setting, and on the other, with having to deal with cold temperatures and biting winds, which are constant companions in these places. This is going to be an incredible journey.
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