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| SUNDAY, OCTOBER 17, 2021 | WISCONSIN STATE JOURNAL
UW-MADISON COLLEGE OF LETTERS & SCIENCE
DEPARTMENT OF GEOSCIENCE
UW-Madison researchers at Saskatchewan Glacier in Banff National Park. From left to right: Collin Roland, Dougal Hansen, Emily Schwans, Nate Stevens and Luke Zoet.
Studying glaciers, from field to freezer LUCAS (LUKE) ZOET
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laciers move, and relative to other geologic processes, a “glacial pace” is quite fast. Glacial ice flows downhill much like a slow-motion river, but unlike a river, most of the motion comes from the ice slipping over the material below. Envision placing an ice cube on an inclined board and watching the pull of gravity causing it to slip downhill. This glacial slipping action causes the glacier to shape the ground underneath it. Most of the land in Wisconsin was overridden by glaciers during the Wisconsin glaciation, and so the shape
and appearance of the landforms are a direct result of glacier slip, from the rise up to the State Capitol and Bascom Hill to the shape of the four lakes of De Jope. Glacier slip is also the main way in which glacier ice is discharged into the ocean and is a primary contributor to sea-level rise. Although the impacts of glacier slip are integral to our lives —from the formation of landscapes to the rising oceans — the process is poorly understood by scientists. Over the decades many theories have been proposed to interpret glacier slip, and countless heroic field campaigns have been conducted to gather the
necessary observations, but it can be difficult to directly test the theories from field data. To address these limitations, we have constructed one-of-a-kind laboratory devices at UW-Madison that are capable of directly simulating glacial slip in a controlled environment. These devices have allowed us to test the existing theories, and we have used them to develop new theories where existing ones have fallen short. One such apparatus is a large-diameter cryogenic ring shear housed in a walk-in freezer. The ring shear can spin a ring of ice (60 cm in diameter) over various
materials commonly found at the bases of glaciers. We can spin the ice ring at a range of velocities and stresses, simulating the full span of conditions that natural glaciers experience. This approach is new in glaciology, a field that has virtually no experimental branch, and from these devices we have been able to test and observe the fundamental mechanics of glacier slip in order to determine the correct theories for predicting glacier motion. We are then able to check these theories against field observations. To examine glacier slip from the field, we pack up a wide range of geophysical
