45o 



University of California. 



[Vol. 2. 



yet to undergo a most extraordinary history. The Merced series 

 on the peninsula of San Francisco only a few miles distant is post- 

 Campan in age. To permit of its accumulation, that portion of the 

 region sank over a mile beneath sea level, and the trough so formed 

 was filled to the brim with marine sediments of late Pliocene, and 

 in their upper part of Pleistocene age. Then this trough was 

 deformed, the floor upon which the Merced was laid down was 

 lifted high above sea level,* the Merced beds were tilted at angles as 

 high as 75 degrees, and were dislocated by a fault having a throw of 

 not less than 7,000 feet. f After this we enter upon the cycle of ero- 

 sion, vertical oscillations of the coast, and minor faulting, which 

 has resulted in the modern geomorphy of the middle Coast Ranges. 



University of California, 



December \ igoi. 



*Cf. this Bull., Vol. I, No. 4. 



t Cf. Sketch of the Geology of San Francisco Peninsula, U. S. G. S. 

 15th Ann. Rpt. 



