Lawson.] 



Coast of Northern California. 



245 



ever, fullv as significant as the marine, and are perhaps more impor- 

 tant in that they indicate an exceptionally long-continued stoppage 

 in the general upward movement. We may now proceed to indi- 

 cate in the briefest possible terms the occurrence of these baselevel 

 bench marks, both marine and fluviatile, along the coast between 

 the Golden Gate and Eureka. 



Between the Golden Gate and the mouth of the Russian River 

 the most prominent of the former strand lines of the coast are the 

 wave-cut terraces of Duxbury Point and Point Reyes. The former 

 is a very distinct plateau-like bench, which has been cut into the 

 southern end and eastern side of the ridge which separates Ballenas 

 Bay from the open ocean. Its elevation is from 220 to 230 feet, 

 according to the Coast Survey contours. The terrace at Point 

 Reyes is broader, and, owing to subsequent degradation, somewhat 

 vaguer than that of Duxbury Point when viewed at close quarters. 

 Its greater breadth may be ascribed partly to the more projecting, 

 and therefore more exposed, position of the point, and partly to 

 the fact that it has been cut into a terrane of soft Miocene shale 

 (Monterey Series) which occupies that portion of the point to the 

 north of the bold ridge of granite and conglomerate upon which 

 the lighthouse is situated. Its partial degradation is due to the 

 imperfect terracing action of later stages of uplift, and to the fact 

 that it is traversed by the drainage of the high ridge to the east of 

 it. This terrace is sparingly strewn with shore-worn pebbles. 

 The elevation of the terrace is about 300 to 330 feet. On Point 

 Reyes there are other lower terraces, but topographically they are 

 quite subordinate to the broad dominant terrace here referred to. 

 On the ocean side of the main coast ridges, which lie to the east of 

 Ballenas and Tomales Bays, there are numerous suggestions of 

 higher terraces, but they are nearly all vague in their profiles and in 

 their horizontal extension. They seem to have suffered severely 

 from degradation, and they occur on a terrane which, in the writer's 

 experience, wherever it occurs along the Californian coast, is little 

 adapted to the preservation of such forms. 



A little north of the mouth of the Russian River well character- 

 ized oceanic terraces, at various high altitudes above the present 

 strand, form prominent features of the coastal topography. The 



