Qa    ALLUVIUM AND COLLUVIUM
Qt    GRAVEL, PEDIMENT, AND FAN DEPOSITS--May include some glacial
         deposits and Tertiary gravels
Qg    GLACIAL DEPOSITS
Qls   LANDSLIDE DEPOSITS
Qs    DUNE SAND AND LOESS
Ql    PLAYA LAKE AND OTHER LACUSTRINE DEPOSITS
Qu    UNDIVIDED SURFICIAL DEPOSITS
                             NORTHWEST
Qb    BASALT FLOWS AND INTRUSIVE IGNEOUS ROCKS
Qr    RHYOLITE FLOWS, TUFF, AND INTRUSIVE IGNEOUS ROCKS
                             SOUTHWEST
Qi    ALKALIC EXTRUSIVE AND INTRUSIVE IGNEOUS ROCKS