UNIVERSITY OF CALIFORNIA PUBLICATIONS 



BULLETIN OF THE DEPARTMENT OF 



GEOLOGY 



Vol. 11, No. 1, pp. 1-44, 6 text-figs., pis. 1-2 March 20, 1918 



THE FRANCISCAN SANDSTONE 



E. F. DAVIS 



CONTENTS 



PAGE 



Introduction .'. 2 



The Franciscan group in California 2 



Extent 2 



Sedimentary rocks 3 



Igneous rocks .7 4 



Metamorphic rocks 5 



The Franciscan group in southern Oregon - 5 



The Franciscan group in Washington 6 



The age of the Franciscan group > 6 



Difficulties encountered 6 



Stratigraphic relations 7 



Overlying rocks 7 



Underlying rocks 7 



Evidence as to the age of the Franciscan in the California Coast Ranges .... 8 



Conclusions based on relations to granite 8 



Possibility of different periods of granitic invasion 10 



Evidence regarding the age of the Franciscan at Slate's Springs 11 



Evidence as to the age of the Franciscan group based on work in Oregon .... 12 



Uncertainty as to the age of the Knoxville 13 



Possibility of a Triassic age for the Franciscan group 15 



The Franciscan sandstone - 16 



Stratification 16 



Occurrence of fossils 17 



Lithologic character 18 



Shale fragments - 23 



Veins 24 



Conglomerates 25 



The origin of the Franciscan sandstone 29 



Lack of fossils 29 



Angularity of grain 30 



Significance of feldspar 30 



