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Mount Churchill
Mount Churchill
is a volcano in the Saint Elias Mountains
Saint Elias Mountains
and the Wrangell Volcanic Field
Wrangell Volcanic Field
of eastern Alaska. Churchill and its higher neighbor Mount Bona about 2 mi (3 km) to the southwest are both large ice-covered stratovolcanoes, with Churchill being the fourth highest volcano in the United States
United States
and the seventh highest in North America.

Contents

1 Volcanic eruptions 2 History 3 References 4 External links

Volcanic eruptions[edit] Mount Churchill
Mount Churchill
is most noteworthy as the source of the White River Ash, deposited during two of the largest volcanic eruptions in North America during the past two millennia. This twin-lobed tephra deposit covers more than 130,000 square miles (340,000 km2) of eastern Alaska
Alaska
and northwestern Canada, with the northern lobe deposited 1900 years ago and extending over 250 miles (400 km) and the larger eastern lobe about 1,250 years ago and stretching over 500 miles (800 km). The total volume of the ash exceeds 12 cubic miles (50 km3), or roughly 50 times the volume of the 1980 eruption of Mount St. Helens, and ash layers up to 2 feet (61 cm) thick can be seen just below the surface in many roadcuts along the Alaska Highway. The extensive ash deposits in the lowlands near the White and Yukon Rivers were first recognized in 1883, but their source remained a mystery for the next century. Geologists in the 1960s traced the two lobes of the ash back into the Saint Elias Mountains, and postulated that the ash may have come from a vent now buried under the Klutlan Glacier, which flows east for over 40 mi (64 km) from the Bona-Churchill massif into the Yukon Territory
Yukon Territory
of Canada. More detailed studies in the 1990s by the U.S. Geological Survey
U.S. Geological Survey
finally produced the definitive answer. Aerial photos showed a 2.6 by 1.7 miles (4.2 km × 2.7 km) elliptical, gently sloping, ice-filled depression at 14,500 feet (4,400 m) just east of the present summit of Mount Churchill. This was identified as a caldera, which had formed by the collapse of the volcano's previous summit during the cataclysmic eruptions. The geological field work revealed thick young pumice deposits along the rim of the caldera which are mineralogically and chemically identical to the White River Ash.

U.S. Geological Survey
U.S. Geological Survey
climbing party reaching the east rim of the summit caldera on Mount Churchill. Blocky debris in the photo consists of pumice and lithic fragments ejected 1,250 years ago, during the eruption which formed the eastern lobe of the White River Ash.

History[edit] Mount Churchill
Mount Churchill
was first climbed in 1951 by R. Gates and J. Lindberg, but the peak was merely an unnamed satellite of Mount Bona at the time. The mountain was named in 1965 by the Alaska
Alaska
State Legislature for English statesman Winston Churchill.[1] In terms of elevation, it is a major North American peak, at well over 15,000 feet (4,600 m); however, in terms of topographic prominence or isolation, it is less significant, with less than a 1200-foot drop from its summit to the saddle with Bona. Churchill also lies on the northern, gentler side of the Bona massif, making it a less visually spectacular peak than some of the lower outliers of Bona such as University Peak or Aello Peak. The current standard climbing route is the South Ridge, usually as part of a climb of Mount Bona from the east starting from a ski-equipped bush plane landing at around 10,000 feet (3,000 m) on the Klutlan Glacier. References[edit]

McGimsey, R. G.; Richter, D. H.; DuBois, G. D.; Miller, T. P. (1992). "A postulated new source for the White River Ash, Alaska". Geological Survey Bulletin. 1999: 212–218.  Richter, D. H.; Preece, S. J.; McGimsey, R. G.; Westgate, J. A. (1995). "Mount Churchill, Alaska; source of the late Holocene White River Ash". Canadian Journal of Earth Sciences. 32 (6): 741–748. Bibcode:1995CaJES..32..741R. doi:10.1139/e95-063.  "Churchill". Global Volcanism Program. Smithsonian Institution. Retrieved 2007-03-10.  Wood, Charles A.; Kienle, Jürgen, eds. (1990). Volcanoes of North America. Cambridge University Press. ISBN 0-521-43811-X.  Richter, Donald H.; Rosenkrans, Danny S.; Steigerwald, Margaret J. (1995). Guide to the Volcanoes of the Western Wrangell Mountains, Alaska. USGS
USGS
Bulletin 2072.  Winkler, Gary R. (2000). A Geologic Guide to Wrangell—Saint Elias National Park and Preserve, Alaska: A Tectonic Collage of Northbound Terranes. USGS
USGS
Professional Paper 1616. ISBN 0-607-92676-7.  Richter, Donald H.; Preller,Cindi C.; Labay, Keith A.; Shew, Nora B. (2006). Geologic Map of the Wrangell-Saint Elias National Park and Preserve, Alaska. USGS
USGS
Scientific Investigations Map 2877.  Wood, Michael; Coombs, Colby (2001). Alaska: A Climbing Guide. Mountaineers Books. ISBN 0-89886-724-X. 

^ "Mount Churchill". Geographic Names Information System. United States Geological Survey. Retrieved 2007-03-10. 

External links[edit]

"Mount Churchill". Bivouac.com. Retrieved 2014-

.