Portland State University. Department of Earth Sciences
Michael L. Cummings
Date of Award
Master of Science (M.S.) in Geology
1 online resource (137 p.)
Areal Geology, Volcanology, Oregon, Hydrothermal Alteration
The Glass Buttes volcanic complex consists of many domes and individual vents that erupted both rhyolitic and basaltic lavas during the late Miocene to early Pliocene. The east half of the complex, in the vicinity of Little Glass Butte, contains interfingering, finely flow-banded rhyolite and black obsidian flows. The youngest unit, an obsidian, has been dated at 4.9 m.y. East of Little Glass Butte lie two northwest-trending ridges, Antelope and Cascade Ridges, composed of two or more overlapping exogenous domes that formed along northwest-trending faults.
Berri, Dulcy Annette, "Geology and hydrothermal alteration, Glass Buttes, Southeast Oregon" (1982). Dissertations and Theses. Paper 3158.