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Posted on 10/17/2014 10:53:40 AM PDT by SunkenCiv
Alaska's Mount Churchill volcano erupted some 1,200 years ago, spreading ash from Canada to Germany...
Mount Churchill is also an impressive volcano, the tallest on land in the United States and one of the towering, snowy peaks of Alaska's Wrangell-St. Elias Mountains. But Churchill's blast in A.D. 843 ejected just 12 cubic miles (50 cubic km) of ash, a layer now called the White River Ash, according to the new study, published in the September 2014 issue of the journal Geology...
If moderate volcanic eruptions can spread ash for thousands of miles, then these blowouts may be more hazardous than scientists think...
The good news is volcanic eruptions of Mount Churchill's size strike only once every 100 years, on average...
The White River discovery also means scientists may start hunting for the origin of mysterious volcanic shards on other continents, instead of close to home... For example, some archaeologically important ash layers in Central America have never been tied to a specific eruption...
By the time the White River ash crossed the Atlantic, it was simply a few sprinkles of microscopic glass shards, not a thick, hefty layer as in Canada's Yukon Territory... study co-author Sean Pyne-O'Donnell, also at Queen's University, discovered the right clue in a Newfoundland, Canada, peat bog.
At first, Pyne-O'Donnell thought the bog would hold Iceland ash, because Newfoundland is closer to the Atlantic island of Iceland than to the Pacific's ring of fire. But the bog instead held ash from Mount Churchill, Mount Mazama (Crater Lake) in Oregon, Mount St. Helens (Washington), and Alaska's Mount Augustine and Mount Aniakchak. The findings were the first step in connecting the White River Ash to Europe's cryptic AD860B tephra.
(Excerpt) Read more at livescience.com ...
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