Anodyne
Thursday, November 01, 2007
 

Melting Glacier Reveals Ancient Tree Stumps

"Melting glaciers in Western Canada are revealing tree stumps up to 7,000 years old where the region's rivers of ice have retreated to a historic minimum, a geologist said today.

Johannes Koch of The College of Wooster in Ohio found the fresh-looking, intact tree stumps beside retreating glaciers in Garibaldi Provincial Park, about 40 miles (60 kilometers) north of Vancouver, British Columbia.

Radiocarbon dating of the wood from the stumps revealed the wood was far from fresh—some of it dated back to within a few thousand years of the end of the last ice age.

'The stumps were in very good condition, sometimes with bark preserved,' said Koch, who conducted the work as part of his doctoral thesis at Simon Fraser University in Burnaby, British Columbia. Koch will present his results on Oct. 31 at the Geological Society of America annual meeting in Denver.

The pristine condition of the wood, he said, can best be explained by the stumps having spent all of the last seven millennia under tens to hundreds of meters of ice. All stumps were still rooted to their original soil and location.

'Thus they really indicate when the glaciers overrode them, and their kill date gives the age of the glacier advance,' Koch said. The age of the newly revealed ancient trees also indicates how long the glaciers have covered this region."
- posted by cjb @ 4:52 PM


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