224 J. S. DILLEK — GEOLOGY OF CALIFORNIA AND OREGON. 



uous, and it follows that the Shasta-Chico series is the result of contin- 

 uous sedimentation. 



The distribution of the members of the Shasta-Chico series and the 

 composition of those in contact with the older rocks, on which they rest 

 unconformably, shows that during their deposition the northern parts 

 of California and Oregon were gradually subsiding and the sea trans- 

 gressing. 



In Oregon the Tejon rests upon the Shasta-Chico series unconformably, 

 and the paleontologic evidence, so far as it goes, tends to show that there 

 is a faunal break in that region between the Chico and the Tejon. 



At the close of the Taylorville Jurassic there was an upheaval, by 

 which the Klamath mountains and the northern end of the Sierra 

 Nevada were outlined and the land extended far northwestward into 

 the Pacific. 



This upheaval was followed after a considerable interval by a sub- 

 sidence, which brought in Aucella from the northwest and inaugurated 

 the Shasta-Chico series. 



In northern California and Oregon the subsidence continued through- 

 out that series, unless interrupted between the Mariposa and Knoxville 

 epochs, and was brought to a close by another mountain-forming 

 upheaval, which forced the sea far to the westward before the begin- 

 ning of the Tejon. 



IT. S. Geological Survey, 



Washington, 1). C. 



