When rocks turn up in unusual places carried along by glaciers, geologist Christian Schlüchter from the University of Bern has a field day.

Thanks to dating techniques he helped develop in the 1990s, Schlüchter and his students are able to use these erratic boulders to work out the former extent of glaciers.

By using sophisticated measuring techniques on the rock samples they collect, they are able to calculate the time these pieces have been exposed to cosmic rays. They are putting the method to good use in an ongoing research project in Antarctica

"This technique means we are actually dating the age of landscapes or moraines," said Schlüchter. "So in an environment where there are almost no organic materials and where there are no other methods to actually date physical features this is a very fascinating method to fill the gap.

"We have been involved in these dating techniques for almost ten years in the Antarctic and we have measured the oldest landscape on earth down there which is older than ten million years old and it still looks the same."

Six Antarctic expeditions

Schlüchter, who specialises in ice age research, has been on six expeditions to Antarctica. He first visited the continent 20 years ago, participating in a US expedition to map out moraines and study sediments to reconstruct the behaviour of the glaciers.

Schlüchter said the sensitive environment in the Antarctic was cause for both wonderment and concern.

"If you look at the sensitivity of the environment from the geological point of view, the erosion rate in that part of the Antarctic continent where you can actually see the geological substrate penetrating the ice is 25, 000 times slower than here in the European Alps," he said.

"So it's an enormous slowing down, it's very sensitive, so all the impacts you produce are seen for many, many years, if not centuries.

"The group I was working with in 1997 found an old foodbox which had been left behind 20-25 years ago. It was absolutely intact. The wood was a bit weathered but all the contents were in perfect shape."

Schlüchter said he was concerned about the development of tourism in Antarctica.

"We should not forget that the tracks you put on that continent will be seen for decades," he said. "We have met our own footprints, 15 years after we passed the first time through one of the valleys. This is such a fragile, delicate environment that you can destroy many things within a second or two."

by Vincent Landon

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