UNIVERSITY OF CALIFORNIA PUBLICATIONS 

 Bulletin of the Department of Geology 



Vol. 3, No. 6, pp. 173=190, PI. 18 ANDREW C. LAWSON, Editor 



THE IGNEOUS ROCKS NEAR PAJARO. 



BY 



John A. Reid. 

 CONTENTS. 



PAGE 



Introductory Note 173 



Occurrence 174 



Geological Relations 174 



Petrographical Types 17(5 



The Main Mass 170' 



Macroscopical Characters 17(i 



Microscopical Characters 177 



The Basic Phase 179 



The Acid Dykes 181 



Aplite 181 



Pegmatite 182 



Khyolitc 184 



Chemical Characteristics 184 



Nomenclature.. 187 



General Discussion 187 



Graphic Representation. 188 



Conclusion 190 



INTRODUCTORY NOTE. 



These notes are offered as a small contribution to the know- 

 ledge of the granitic rocks of the Coast Ranges of California. 

 No attempts at the correlation of these rocks have yet been made, 

 and the following notes are presented in the hope that they may 

 be a start in the right direction, and of service to other workers. 

 Several interesting and important questions have arisen, chiefly 

 on the nomenclature of intermediate rock types of basic compo- 

 sition, and it is the aim of this paper to call attention to them.* 



*My acknowledgments are due Professor A. C. Lawson, under whose care 

 and advice this work was completed. 



