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Fireside Lecture on ancient shorelines of SE Alaska
JUNEAU, Alaska, Feb. 13, 2017 – Geologist Jim Baichtal talks about revising old theories regarding how life adapted to Southeast Alaska’s ancient ice sheets during the Fireside Lecture on Friday, February 17 at Mendenhall Glacier
Visitor Center. Once thought to be completely covered by glacial ice to the shoreline, Southeast Alaska is now believed to have had significant ice-free refuge areas where people, plants and animals lived.
“Exploration of caves yielded bones of mammals, birds and fish dating beyond the limits of radiocarbon dating methods,” said Baichtal. “Discoveries revealed that animals have been on the landscape for well over 50,000 years, refuting previous
models of glaciation.” The new model for glaciation involves the dynamic processes of glacial ice on the land and sea levels. As the glaciers grew, global sea levels fell, Baichtal writes. The weight of the advancing glaciers depressed the earth’s surface while
pushing up a forebulge along their front. As the glaciers melted, sea level rose and the lands depressed by the weight of the ice rapidly rebounded and the forebulge collapsed. Subsequent tectonic uplift has further changed the landscape. Deposits of ocean shells found high on mountain slopes helped to define just where past shorelines were and the timing of deglaciation. These deposits also helped to predict early human habitation sites, which archaeological investigations
have confirmed. “This information is absolutely fascinating,” said Tongass National Forest naturalist Laurie Craig. “I am thrilled Jim will be presenting it to our Fireside audience.” Fireside Lectures are free and occur at 6:30 p.m. and repeat at 8 p.m. Doors open at 6 p.m. Elevators are closed for replacement. Access to the visitor center is via an outdoor ramp or stairs. For more information, contact Laurie Craig
at 907 789-0097 or lcraig@xxxxxxxxx.
Deposits of ocean shells help to define where past shorelines were. This electronic message contains information generated by the USDA solely for the intended recipients. Any unauthorized interception of this message or the use or disclosure of the information it contains may violate the law and subject the violator to civil or criminal penalties. If you believe you have received this message in error, please notify the sender and delete the email immediately. To manage your subscription visit http://www.fs.fed.us/news/subscription.shtml |
