Deceptively Fresh Trees Evidence of Glacial Melt

3 11 2007

A geologist has radiocarbon-dated tree stumps found at the foot of glaciers in Western Canada and found them to be 7,000 years old. The stumps, which look fresh and are rooted to their original soil and location, appear as they do due to their being buried under glacial ice for 7,000 years.

Geologist Johannes Koch of The College of Wooster who ran the tests, said of the trees “They really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance,” Koch explained. They also give us a span of time during which the glaciers have always been larger than they were 7000 years ago – until the recently warming climate released the stumps from their icy tombs.”

While there have been many advances and retreats of these glaciers over the past 7000 years, no retreats have pushed them back so far upstream as to expose these trees. Koch points to global warming to explain the recent rapid glacial retreat.

“It seems like an unprecedented change in a short amount of time,” Koch said. “From this work and many other studies looking at forcings of the climate system, one has to turn away from natural ones alone to explain this dramatic change of the past 150 years.”

Koch presented his findings at the recent GSA Conference.

From Terra Daily, via UC Davis Geology in the News

Note: I blogged this while watching the horrific Dantes Peak on TV. Big nasty volcano!




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