Mount Churchill * * * contains an ice-filled summit caldera 3 km wide." McGimsey and others (1992) [2] show that Mount Churchill is the source of the White River Ash, produced during two of the largest explosive eruptions in North America during the last 2000 years.

On geochemical plots, WRA-Eb samples are on linear extensions toward higher silica content and lower temperature estimates compared to WRA-Ea samples, strongly suggesting a genetic link. WRA-Eb samples represent a younger eruption or eruptions from the evolving Mount Churchill magmatic system."

McGimsey and others (1992) and Richter and others (1995) questioned the likelihood of a vent located at the floor of a valley lacking an edifice or nearby volcano, and proposed that Mount Churchill was the vent.

The prominent ridge just to the right of Mount Bona's peak is Mount Churchill, which is notable for being the source of one of the most recent colossal (VEI = 6) eruptions in Alaska's history - the White River Ash East Lobe eruption of ~800 CE.

Description: From Richter and others (1995): "The exception to the tephra occurrences along the south-east ridge [of Mount Churchill summit area] is an outcrop of flow-banded dacite ([sample number] 90ADg-3) that underlies the tephra. The dacite is a pyroxene-bearing, hornblende dacite, mineralogically distinct from the tephra (see modes, Table ...

Mount Churchill, Alaska: source of the late Holocene White River Ash Author(s): Richter, D. H., McGimsey, R. G., Preece, S. J., and Westgate, J. A. Publication Year: 1995

U.S. Geological Survey climbing party ascending the Klutlan Glacier en route to 4,766- m (15,636 ft)-high Mount Churchill. This volcano was the site of two of the most voluminous explosive eruptions in North America in the past 2,000 years.

AVO personnel sample a roadside outcrop of White River Ash-East (a volcanic ash left by an extremely large eruption of Mt. Churchill) south of Pelly Crossing, Yukon Territory. The ash is visible as a light gray layer underneath the modern vegetation and soil.

Volcano(es): Churchill, Mt Bona, Mt Photographer: US Geological Survey URL: avo.alaska.edu/image/view/651

Graduate Student working on Mount Churchill Discipline(s): UAF Graduate Student USGS Volcano Notification Service