Alaska Volcano Observatory

Granodiorite from the Shaler pluton near the contact on the ridge between Blueberry Bay and Three Island Bay. The texture is hypidiomorphic- granular. Felsic minerals compose 70-80 percent of the rock: 10-15 percent quartz with undulatory extinction, 5-10 percent orthoclase partly altered to kaolin (

Sample Location:

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Legend

	Red (Warning)
	Orange (Watch)
	Yellow (Advisory)
	Green (Normal)
	Uninstrumented

100 km

50 mi

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References Cited

[1] Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska, 1961

Drewes, Harald, Fraser, G. D., Snyder, G. L., and Barnett, H. F. Jr., 1961, Geology of Unalaska Island and adjacent insular shelf, Aleutian Islands, Alaska: in Investigations of Alaskan volcanoes, U.S. Geological Survey Bulletin 1028-S, p. 583-676, 3 sheets, scale 2 at 1:250,000 and 1 unknown.

full-text PDF 3.3 MB

plate 75 PDF 6.7 MB

plate 76 PDF 113 KB

plate 77 PDF 250 KB

table 1 PDF 326 KB

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