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Inside Iowa State
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April 13, 2001

At work between a rock and . . . ice

by Skip Derra
Research under a glacier is hard work. Just ask Neal Iverson, assistant professor of geological and atmospheric sciences, who spent 10 days living and working under a glacier at the Svartisen Glaciological Observatory in Norway. But at least the weather was predictable.

Temperature and humidity are nearly constant (at 35 F and 100 percent) and wind, nominal, in what can best be described as a cool February without sunlight. Living and working in a series of tunnels in rock and ice means rarely getting a chance to see the sun. That would require a 30-minute walk to the surface. Not a good use of time when working 15-hour days.

"It's not a pleasant place to work," Iverson said dryly.

And the work is hard. Moving gear and equipment for experiments is a test of stamina and willpower. The team moved 3 tons of sediment, which was used in its experiments, in 5-gallon buckets up 125 stairs. Because the location of the experiment was 100 feet beyond their access tunnel, the researchers had to "drill" into the ice. They blasted hot water onto the glacier until they had carved their way to the desired point.

But ice doesn't stand still. Iverson said that the extreme pressure (they were under 700 feet of ice) causes the ice to act like toothpaste -- it squeezes into any empty cavity it can find. If left untended, the ice would fill the 6-foot high by 100-foot long tunnel in about two days.

This meant part of their daily routine was spraying hot water onto the ice to keep the tunnel open. Cold, wet and standing in mud puddles was de rigueur for the team.

"In geology, it's tradition to work long, hard days," Iverson said. "You have a short time to get your data. You tend to work hard obtaining it."

For the experiments, the group blasted a 6-foot by 6-foot by 2-foot trough into the rock, inserted the sediment, together with instruments (to measure stresses and glacier motion and sediment deformation), and then let the ice squeeze back over their test bed. Then, the tests began.

As the glacier moved over the trough, the researchers could measure the stresses and strains put on the nearby rock. Data analysis remains to be done, but Iverson said it is clear the glacier is sliding over its bed at a rate of about 7 inches per day -- a fast, but not unusual rate for a glacier. Friction between the ice and rock appeared greater than the researchers expected.

What all of it means is still up in the air. Iverson will return to his place under the ice next spring, at roughly the same time birds begin to chirp and trees begin to bud, for another mole's eye view of glacier movement.

Iowa State geologist Neal Iverson brought back this photo of his colleague, Denis Cohen of Yale University, in a tunnel under the glacier. Cohen is standing on rock; at knee level is sediment-rich basal ice; at chest and head level is clean ice. Photo by Neal Iverson.

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