146 University of California. [Vol. 2. 



GEOMORPHY. 



The present relief of the peninsula is not complex and may 

 best be described under the following headings, each of which 

 represents a distinct stage in its historical development, though 

 not all of the stages are included. 



Main Ridges. — The greatest elevations are found in the prin- 

 cipal ridge following the western shore of Tomales Bay, two points 

 of which attain a height of about 1,300 feet. Between and on 

 either side of these the altitude of the ridge declines. Whitten- 

 berg Hill stands about two miles southwest of Point Reyes Station. 



Figure 3. — Whittenberg Hill, looking south ; Olema on the left, ocean on the right. A 



It consists mainly of granite mantled over from the west by a 

 tolerably thick monocline of Miocene sediments. Its northern and 

 western slopes are accordingly much more gentle than its southern 

 and eastern, which are rather abrupt. Five miles to the northwest 

 and nearly opposite the head of Drake's Estero is a more broadly 

 rounded granitic dome somewhat higher than Whittenberg, known 

 as Vision Hill. Its summit is oblong, consisting of a few minor 



A Figure 4. — Profile of Vision Hill, looking north ; ocean on the left, Tomales Bay C 



on the right. 



rocky points resting upon a rounded mesa-like platform from 

 which extend a number of bold radial ridges. The summit of this 

 platform probably represents a miniature peneplain. The ridge 

 between these two elevations is a succession of lower summits 

 mainly or entirely made up of granite rocks. North of Vision 

 Hill the ridge is similarly a succession of hills gradually declining 

 in elevation in the direction of Tomales Head. 



