Ancient Forest Thaws From Melting Glacial Tomb

Thursday, September 26, 2013

Ancient Forest Thaws From Melting Glacial Tomb

By Laura Poppick, Staff Writer | September 20, 2013 09:31am ET

Stumps have been thawing from beneath the Mendenhall Glacier for about 50 years, but recently, considerably more have been found in upright positions with roots still intact.
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: Jamie Bradshaw

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An ancient forest has thawed from under a melting glacier in Alaska and is now exposed to the world for the first time in more than 1,000 years.
Stumps and logs have been popping out from under southern Alaska's Mendenhall Glacier — a 36.8-square-mile (95.3 square kilometers) river of ice flowing into a lake near Juneau — for nearly the past 50 years. However, just within the past year or so, researchers based at the University

of Alaska Southeast in Juneau have noticed considerably more trees popping up, many in their original upright position and some still bearing roots and even a bit of bark, the Juneau Empire first reported last week.
"There are a lot of them, and being in a growth position is exciting because we can see the outermost part of the tree and count back to see how old the tree was," Cathy Connor, a geology professor at the University of Alaska Southeast who was involved in the investigation, told LiveScience's OurAmazingPlanet. "Mostly, people find chunks of wood helter-skelter, but to see these intact upright is kind of cool."

The team has tentatively identified the trees as either spruce or hemlock, based on the diameter of the trunks and because these are the types of trees growing in the region today, Connor said, but the researchers still need to further assess the samples to verify the tree type.
A protective tomb of gravel likely encased the trees more than 1,000 years ago, when the glacier was advancing, Connor said, basing the date on radiocarbon ages of the newly revealed wood. As glaciers advance, Connor explained, they often emit summer meltwater streams that spew aprons of gravel beyond the glacier's edge. [Images: Shrinking Alaska Glacier Spied from Space]
A gravel layer about 4 to 5 feet (1.2 to 1.5 meters) high appears to have encased the trees before the glacier ultimately advanced enough to plow over them, snapping off limbs and preserving the stumps in an ice tomb.

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