STUDIES, SCIENTIFIC AND SOCIAL 



valley-formation, Professor Whitney has been led to adopt 

 one which has hardly yet been recognised by geologists 



Fig. 3— sentinel rock, 3,069 feet, looking up valley. 



as probable or even possible, and which he describes as 

 follows : 



We conceive that, during the process of upheaval of the Sierra, 

 or, possibly, at some time after that had taken place, there was at 

 the Yosemite a subsidence of a limited area, marked by lines of fault 



