UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 1 1, No. 2, pp. 45-234, 4 text-figures, plates 3-24 Issued July 16, 1918 



THE SAN LORENZO SERIES OF MIDDLE 

 CALIFORNIA 



A STRATIGRAPHIC AND PALAEONTOLOGIC STUDY OF THE 

 SAN LORENZO OLIGOCENE SERIES OF THE GENERAL 

 REGION OF MOUNT DIABLO, CALIFORNIA 



by ^ ^ p\an Inst/f^N 



BEUCE L. CLAEK 



f Zonal *»*f 



CONTENTS 



PAGE 



Introduction : 53 



Acknowledgments 56 



Eeview of literature pertaining to the marine* Oligocene of the West Coast 57 



Descriptions of local sections of San Lorenzo series .. 72 



San Lorenzo series to west and south of Mount Diablo 73 



General statement 73 



San Lorenzo series of the Sobrante anticline 74 



San Ramon formation 74 



Kirker tuffs 75 



Concord formation 75 



Evidence for a stratigraphic break between the San Lorenzo and the 



Monterey 76 



San Lorenzo series of the San Ramon syncline 77 



General statement 77 



San Ramon formation on west side of syncline 78 



Lithology 78 



Relation to Tejon 78 



Lithology of Lower Monterey (Miocene) 79 



Evidence for stratigraphic break 79 



Summary of section of San Ramon formation 80 



San Ramon formation on east side of San Ramon syncline 80 



Occurrence and lithology 80 



Relation to Monterey (Miocene) 81 



San Lorenzo series in Pacheco syncline 81 



