liK)4.J 



HAEHL AND ARNOLD— THE MIOCENE DIABASE. 



21 



theory is supported by the fact that, where typically developed, the 

 Monterey shale is between twenty-five hundred and three thousand 

 feet thick and rests on a comparatively thin layer of sandstone, 

 while, in the area under discussion, the relative proportions of shale 

 and sandstone are exactly the reverse. The harder, more flinty 

 shales which appear along the coast are not found in the vicinity of 

 the diabase. 



Fig. 2, View on the Searsville-La Honda road three-fourths mile south of sum- 

 mit, looking east, showing the Miocene shale beds resting against the dia- 

 base which has intruded them in sill-like dikes. The man points at the 

 contact. Photograph by Ralph Arnold. 



The following species of fossils have been found in the Monterey 

 shale within the diabase area : 



Monterey Shale {Miocene). — Those 

 so far as known. — 



'^'Leda sp. A. and B. 



List of Fossils from the 

 marked (*) are characteristic, 

 "^Arca montereyana Osmont 

 Callista angustifrons Conrad 

 Chione mathewsonii Gabb 

 * Corbiila sp. A. 

 Cylichna cf. petrosa Conrad 

 Cythera cf. vespertina Conrad 

 "^Diplodonta n. sp. aff. s err i cat a 

 Reeve 



Pecten peckha7ni Gabb 



Pecten {Plagioctemum) n. sp. E. 

 '^Sejnele n. sp. A. 



Siliqua sp. A. 

 * Tellijia congesta Conrad 



