Geologic setting of the Glacier Peak and Mazama ash-bed markers in west-central Montana

1975 ◽  
1984 ◽  
Vol 21 (1) ◽  
pp. 36-41 ◽  
Author(s):  
Peter J. Mehringer ◽  
John C. Sheppard ◽  
Franklin F. Foit

At Sheep Mountain Bog, near Missoula, Montana, a late-glacial tephra, that probably fell in late summer, is preserved as an 8-mm-thick graded bed overlain by another 8 mm of redeposited ash mixed with lake deposits. Sediment surrounding the ash was 14C dated to about 11,200 yr B.P. Electron-microprobe analyses of the volcanic glass and hornblende phenocrysts from this ash layer indicate that they are similar in major-element chemistry to those of Glacier Peak layer G previously considered to be about 12,000 yr old or older.


2010 ◽  
Vol 118 (3) ◽  
pp. 295-304 ◽  
Author(s):  
Francis Ö. Dudás ◽  
Vladimir O. Ispolatov ◽  
Stephen S. Harlan ◽  
Lawrence W. Snee

2014 ◽  
Vol 78 (5) ◽  
pp. 791-807 ◽  
Author(s):  
Hugh S. Robinson ◽  
Richard Desimone ◽  
Cynthia Hartway ◽  
Justin A. Gude ◽  
Michael J. Thompson ◽  
...  

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