Charles Bentley: Remembering UW-Madison glaciologist and Antarctic pioneer

Charles R. Bentley, an intrepid University of Wisconsin-Madison glaciologist and geophysicist who was among the first scientists to measure the West Antarctic Ice Sheet in the late 1950s, died Aug. 19 in Oakland, California. He was 87.

Bentley spent the bulk of his career studying the Antarctic Ice Sheet and the continent beneath it.

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    Dr. Charles Bentley examining an ice core sample taken from an Antarctica expedition.

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    Dr. Charles Bentley (far left) and some of the Antarctic crew during a 1957 expedition across West Antarctica. The group used tracked vehicles to make the first geophysical measurements of the ice sheet.

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    Professor emeritus Charles Bentley inspecting the barrel of the Blue Ice Drill, designed and built by the UW-Madison IDDO team.

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    Dr. Bentley during an Antarctic expedition.

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    Charles Bentley’s first trip to Antarctica was in 1957 and his last in 2009 at age 80. Over the past seven decades, Charles Bentley conducted numerous studies of glaciology and geophysics in Antarctica.

Beginning in 1957, Bentley spent 25 consecutive months on the ice in Antarctica, at a time when scientists from around the world were converging on the continent as part of the International Geophysical Year. During that time, he served as the seismologist on a five-person expedition that motored in tracked vehicles called Tucker Sno-Cats from Little America (a U.S. base near the edge of the Ross Ice Shelf) to Byrd Station in interior West Antarctica on a nearly 700-mile traverse. After wintering over at Byrd Station, Bentley and his colleagues continued their explorations of the continent for a total of almost 3,000 miles of traversing the then almost completely unexplored Antarctic.

During the expedition, Bentley and his colleagues made the first detailed measurements of the depth of the ice sheet. To measure the underlying snow and ice, the team unspooled hundred of meters of cables attached to geophones set on the ice surface to record explosions set off in the ice. The explosions sent sound waves to the bottom of the ice sheet, which reflected back to the geophones to provide a measure of the depth of the ice. To their surprise, they found the ice sheet, which in places is as much as 3,000 meters thick, to be as far below sea level as it was above, making it a marine ice sheet.

That finding resonates today as marine ice sheets are particularly vulnerable to melting and collapse in climate change scenarios.

“During those first 25 months in Antarctica, Bentley led geophysical traverses that fundamentally changed our view of the ice sheet – far from being a thin layer draped over high mountains, the ice in places was well over two miles thick, with a surface high above sea level but a bed that plunged far below, including into the Bentley Trench, the deepest point on the Earth’s surface not now under the ocean,” says Richard Alley, a former student of Bentley’s who is now the Evan Pugh Professor of Geosciences and the EMS Environmental Institute at Penn State University.

Bentley made at least 15 trips over seven decades to the ice. He celebrated his 80th birthday on his last trip to Antarctica in 2009, nearly 50 years after first setting foot on the continent. In Antarctica, Mount Bentley, the highest peak in what are now known as the Ellsworth Mountains, and the Bentley Subglacial Trench, an ice-filled trench the size of Mexico, are named in his honor. “I claim to be the only person with a hill and hole named after him,” Bentley told an interviewer in 2008.

by Terry Devitt

This story was originally published by UW-Madison News: http://news.wisc.edu/charles-bentley-pioneering-uw-madison-glaciologist-dies/