BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 14, pp. 227-268, PLS. 21-31 JULY 10, 1903 



CLASTIC DIKES 



BY J. F. NEWSOM 



CRead before the Society January 1, 1903) 

 CONTENTS 



Page 



Introduction 227 



Sandstone dikes in San Luis Obispo county, California 229 



Location 229 



Geologic relations 229 



Character of the dikes 231 



Description of the dikes 231 



Summary of the Graves Creek dikes 234 



Conclusions as to origin of the Graves Creek dikes 235 



Sandstone dikes near Santa Cruz, California 235 



Location 235 



Geologic relations of the district 236 



Dikes at the asphalt rock quarries 237 



Summary and conclusions as to dikes at asphalt rock quarries 241 



Dikes along the coast west of Santa Cruz 241 



Location 24 1 



Description of dikes along the coast 242 



Summary and conclusions 250 



Clastic dikes observed elsewhere by the writer 252 



Near Stanford University, California 252 



Near Morrilton, Arkansas 253 



At Zaukeroda, Saxony 253 



Clastic dikes previously described 254 



General summary 267 



Introduction 



Classic dikes have been of interest and have been regarded somewhat 

 as anomalies ever since the origin of igneous dikes became fixed in the 

 minds of geologists. This fact is made apparent by a review of the liter- 

 ature concerning the dikes of sedimentary materials described in various 

 parts of the world. Most of such dikes are small, and were they of igne- 

 ous materials would scarcely call for remark. 



XXXIII— Bull. Geol. Soc. Am.. Vol. U. 1902 (227) 



