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Status of glacial Lake Columbia during the last floods from glacial Lake Missoula

Quaternary Research

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DOI: 10.1016/0033-5894(87)90076-7

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Abstract

The last floods from glacial Lake Missoula, Montana, probably ran into glacial Lake Columbia, in northeastern Washington. In or near Lake Columbia's Sanpoil arm, Lake Missoula floods dating from late in the Fraser glaciation produced normally graded silt beds that become thinner upsection and which alternate with intervals of progressively fewer varves. The highest three interflood intervals each contain only one or two varves, and about 200-400 successive varves conformably overlie the highest flood bed. This sequence suggests that jo??kulhlaup frequency progressively increased until Lake Missoula ended, and that Lake Columbia outlasted Lake Missoula. The upper Grand Coulee, Lake Columbia's late Fraser-age outlet, contains a section of 13 graded beds, most of them sandy and separated by varves, that may correlate with the highest Missoula-flood beds of the Sanpoil River valley. The upper Grand Coulee also contains probable correlatives of many of the approximately 200-400 succeeding varves, as do nearby parts of the Columbia River valley. This collective evidence casts doubt on a prevailing hypothesis according to which one or more late Fraser-age floods from Lake Missoula descended the Columbia River valley with little or no interference from Lake Columbia's Okanogan-lobe dam. ?? 1987.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Status of glacial Lake Columbia during the last floods from glacial Lake Missoula
Series title:
Quaternary Research
DOI:
10.1016/0033-5894(87)90076-7
Volume
27
Issue:
2
Year Published:
1987
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Quaternary Research
First page:
182
Last page:
201
Number of Pages:
20