356 CALIFORNIA ACADEMY OF SCIENCES. 



Bulla uebulosa Gould. Haliotis cracherodii Leach. 

 Cerithidea calif ornica Haldemanu. Liocardium substriatrim Conrad. 



Cerostoma nuttalli Conrad. Ostrea lurida Carpenter. 



Chione simillima Sowerby. Pachydesmacrassatelloides Conrad. 



Chione succincta Valenciennes. Pecten aequesulcatus Carpenter. 



Chlorostoma gallina. ScliizothcErus nuttalli Conrad. 

 Crepidiila excavata Broderip. 



This fauna is very similar to that on the beach below 

 at the present time. 



With the exception of one point no trace of a non- 

 conformity was found between the Pliocene and Quater- 

 nary at San Pedro Hill. At one point a V-shaped bed of 

 fine gravel appears in the underlying Pliocene. At first 

 glance it looks like an old stream filling; but examined 

 closely, the edges of the gravel bed are not as sharply 

 defined from the rest of the layer as that theory would 

 seem to require. Though the transition is made in a dis- 

 tance of two or three inches, the two deposits seem to 

 blend along that line as though they were local variations 

 of deposition. The resemblance to a stream cut filling 

 is so strong, however, that the writer believes that a more 

 careful examination is required before we can accept 

 Prof. Lawson's theory of the relation of the Pliocene and 

 Quaternary. In brief, that theory is, that the Pliocene 

 was a period of subsidence and the Quaternary a period 

 of elevation.* 



; IGNEOUS ROCKS. 



Granite. — The existence of granite just south of the 

 area of the detail map near Point San Pedro has already 

 been mentioned. Until the opportunity has been afforded 

 to make more careful observations on the granite, the 

 writer prefers not to commit himself to any theory as to 

 its age or relations to the other formations. 



Old Ei'u^tives. — Over much of the country where the 



"^ UniT. of Cal., Bull. Dept. Geol., vol. i, p. 57. 



