Volcano Photos

Churchill Volcano, USA

 Churchill Volcano, USA, Volcano photo

Churchill Volcano, USA

A U.S. Geological Survey climbing party ascends the Klutlan Glacier en route to 4766-m-high Mount Churchill.

Their field studies led to the recent discovery that this volcano was the site of two of the most voluminous eruptions in North America in the past 2000 years.

The White River Ash, two voluminous ash layers that extend across most of Canada's southern Yukon, originated from the summit caldera of Churchill volcano, which forms a twin volcano with 5005-m-high Mount Bona.

The two peaks comprise the highest volcano in the United States.

The Bona-Churchill massif in the St. Elias Mountains forms the highest Quaternary volcano in the United States.

A 2.7 x 4.2 km wide caldera caps the summit of 4766-m-high Mount Churchill, which is now known to be the source of the White River Ash, produced during two of the largest explosive eruptions in North America during the past 2000 years (McGimsey et al. 1992).

The 5005-m-high summit of Mount Bona lies 4 km across a high saddle from the younger Mount Churchill.

The source vent of the widespread bilobate White River Ash deposit, which blankets more than 340,000 sq km of eastern Alaska and NW Canada, was initially thought to be a pumice mound that is mostly buried beneath the Klutlan Glacier NE of Churchill volcano.

More recent work has revealed thick young pumice deposits mineralogically and chemically similar to the White River Ash deposits along the rim of the Mount Churchill caldera.

PHOTO SOURCE: Game McGimsey (U.S. Geological Survey, Alaska Volcano Observatory), courtesy of the Global Volcanism Program, Smithsonian National Museum of Natural History, used with permission.

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