40 University of California Publications. [Geology 



PAGE 



Age 54 



San Pablo (?) 54 



Pre- Volcanic Beds near Freestone 54 



Pre-Volcanie Beds at Trenton 55 



Pre- Volcanic Beds of Pleasant and Capay Valleys 55 



Age 56 



Orindan (?) 56 



Ked Gravels of Santa Kosa Valley 56 



Sedimentaries Beneath Andesite on Petaluma Creek 57 



Lignitic Beds of Lawlor's Ranch 57 



Lignitie Beds of Mark West Creek 58 



Age 58 



Later Pliocene 58 



Mark West Andesite 59 



Areal Distribution and Thickness 59 



Structure 59 



Age 59 



Petrography ; 60 



Sonoma Tuff 64 



Character of the Tuff 64 



Areal Distribution and Thickness 64 



Interbedded Sandstones and Conglomerates 65 



Lava Flows Within the Sonoma Tuff 65 



Petrography 66 



Age 67 



Marine Beds of Wilson's Ranch 67 



Lithological Character 67 



Areal Distribution 67 



Age and Correlation 69 



St. Helena Rhyolite 69 



Field Aspects, Areal Distribution and Thickness 69 



Petrography 69 



Becker 's ' ' Asperite " 71 



Age of the Above Series 72 



Thickness 73 



Correlation of the Neocene Strata 74 



Quaternary 76 



Tomales Bay Deposits 76 



Bodega Bay Deposits 76 



Flood-Plain Deposits 77 



Structure 78 



Folding of the Merced 78 



St. Helena Fault _ 78 



Age 78 



San Bruno Fault 79 



Evidence of Faulting at Bodega Bay 79 



Age 80 



