Special Papers, Numéro 115

abundant analysis andesite assemblages associated basalt basin batholith beds biotite breccias calcite Calif California Cambrian carbonate cent chemical chert clay coal Colorado composition contain continental cores correlation Creek Cretaceous crystals deformation deposits Dept depth developed Devonian dikes diorite distribution dolomite earthquake environment facies fault fauna feet feldspar flow folds Formation formed fossils fractures Geology Geophysics glacial gneisses granite hornblende indicate intrusion Lake late layers limestone lower magma major marine metamorphic miles minerals Miocene Mountain occur olivine Ordovician Paleozoic pattern phase plagioclase Pleistocene Pliocene pluton Precambrian pressure probably pyroxene quartz quartz monzonite range ratios reef regional rhyolite Ridge River rocks samples sand sandstone sea level sedimentary sediments sequence shale shelf silicic slope southern species strata stratigraphic structure suggest surface tectonic temperature Tertiary texture thick tion trend tuff U. S. Geological Survey units University uplift upper Valley variation volcanic X-ray zone