U.S. Geological Survey Bulletin, Issue 2132U.S. Government Printing Office, 1996 - Geology |
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12 on plate ages of volcanic Analytical data andesitic Archean gneiss basins in southwestern Beaverhead Mountains beds of unit biotite crystals Brent Dalrymple Challis Volcanic Group crystal-lithic tuff data for single-crystal deposited dikes and air-fall Eocene fine-grained glass matrix Horse Prairie basin J.W. M'Gonigle J₁ Janecke and Snee K/Ca lacustrine Lemhi Pass Lodge basin figs M.H. Hait M'Gonigle and M.H. Maiden Peak spur Medicine Lodge basin Miocene Muddy Creek basin Oligocene overlain Paleontologic phenocrysts plagioclase potassium feldspar crystals Proterozoic pumice fragments quartz quartz and potassium Ralph Nichols Red Rock Hills relict shard structure rhyolitic Sage Creek Basins sample localities sample numbers sanidine crystals Sedimentary Basins sedimentary rocks southwest Montana southwestern Montana Staatz stratigraphically study area Tendoy Mountains fig Tertiary sedimentary sequence Tsll Tslt tuff contains tuff unit Tmlt U.S. Geological Survey unit Tcv unpub volcanic dikes Volcanic Group rocks volcanic rocks Weighted Mean Obest western Horse Prairie