Unconsolidated talus, stream, and floodplain deposits in the mountains^ and Lake Bonneville deposits and semi-consolidated pediment gravel, fanglomerate, and other basin-fill deposits in the valleys. Total thickness locally may exceed 1,000 m Qt TUFA OF WAH WAR SPRINGS (HOLOCENE AND PLEISTOCENE) Low mounds of gray, porous, calcareous tufa, possibly deposited when the spring water was somewhat hotter than at present* A maximum of 40 m thick Td DIABASE PLUG AND DIKE (PLIOCENE?) Suspected plug in SW 1/4 sec. 15, T. 29 S., R. 13 W. consists of light-brownish-gray, aphanitic rock now reduced to a thick rubble. Dike rock has slightly sugary texture and small phenocrysts of labradorite and chloritized augite BASALT OF BRIMSTONE RESERVOIR AREA (PLIOCENE?) Tb Flow member Black to medium-gray, fine-grained, locally vesicular or amygdular lava flows. Contains small phenocrysts of augite, hornblende, and andesine (or labradorite) in a felted matrix of plagioclase feldspar, glass, and magnetite. May approach augite andesite in composition. Age may be as young as early Pleistocene. Locally is more than 500 m thick Tbt Basaltic conglomerate and tuff member Nonresistant unit containing cobbles and boulders of basalt and all older rocks, including quartzite and limestone, in a matrix of calcareous volcanic ash. In areas where it is not capped by flow member, the weathered surface is commonly littered by a residuum of boulders and cobbles of vesicular basalt. Maximum thickness of about
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