BEIJING, Oct. 31 (Xinhuanet) -- Glaciers melting in Western Canada are
uncovering fresh-looking, intact tree stumps up to 7,000 years old, a geologist
said Tuesday.
Johannes Koch of The College of Wooster in Ohio found the 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 sine of the
wood 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 can best be explained by the stumps
having spent all of the last seven millennia under tens to hundreds of meters of
ice, he said. 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.
Koch compared the kill dates of the trees in the southern and northern
Coast Mountains of British Columbia and those in the mid- and southern Rocky
Mountains in Canada to similar records from the Yukon Territory, the European
Alps, New Zealand and South America. He also looked at the age of Oetzi, the
prehistoric mummified alpine "Iceman" found at Niederjoch Glacier, and similarly
well-preserved wood from glaciers and snowfields in Scandinavia.
The radiocarbon dates seem to be the same around the world, according to
Koch. There have been many advances and retreats of these glaciers over the past
7,000 years, but no retreats that have pushed them back so far upstream as to
expose these trees.
(Agencies)
