A postulated new source for the White River Ash, Alaska: A section in Geologic studies in Alaska by the US. Geological Survey, 1990

Bulletin 1999
By: , and 

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Abstract

The White River Ash (Lerbekmo and others, 1968), product of two of the most voluminous pyroclastic eruptions in North America in the past 2,000 yr, blankets much of the Yukon Terrtory, Canada, and a small part of adjoining eastern Alaska. Lerbekmo and Campbell (1969) narrowed the source of the ash to an area northeast of the Mt. Bona-Mt. Churchill massif in the St. Elias Mountains of southern Alaska. Based on indirect evidence, Lerbekmo and Campbell (1969) further suggested that the vent was beneath the Klutlan Glacier, adjacent to a mound of coarse pumice, 16 km northeast of Mt. Bona. Recently discovered pumice and ash deposits and a possible vent structure near the summit of Mt. Churchill suggest an alternate source area. The White River Ash is a bilobate plinian fallout deposit covering more than 340,000 km2 and containing an estimated 25-50 km3 of tephra (Bostock, 1952; Berger, 1960; fig. 1). Radiocarbon ages indicate that the northern lobe was deposited about 1,887 yr B.P. and the eastern, and larger, lobe about 1,250 yr B.P. (Lerbekmo and others, 1975). The axes of the two lobes converge near Mt. Bona (16,420 ft (5,005 m)) and Mt. Churchill [15,638 ft (4,766 m)], which together form a prominent massif in the St. Elias Mountains. The Klutlan Glacier, a large valley glacier that flows eastward into Canada, has its principal source on the eastern flank of the massif. 

Publication type Report
Publication Subtype USGS Numbered Series
Title A postulated new source for the White River Ash, Alaska: A section in Geologic studies in Alaska by the US. Geological Survey, 1990
Series title Bulletin
Series number 1999
DOI 10.3133/70180193
Year Published 1992
Language English
Publisher U.S. Geological Survey
Publisher location Denver, CO
Contributing office(s) Alaska Science Center, Volcano Science Center
Description 7 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Geologic studies in Alaska by the US. Geological Survey, 1990 (Bulletin 1999)
First page 212
Last page 218
Country United States
State Alaska
Other Geospatial White River
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