— 34 — 



PART lY. 



REMARKS ON THE FOSSILS COLLECTED BY DR. S. BOWERS, 



IN ORANGE COUNTY. 



In relation to Dr. Bowers' collections the following observations 

 seem necessary, being called for on account of my identification of the 

 fossil mollusca collected by him: 



(1) Quaternary Deposit. — That of San Joaquin Bay, containing 60 

 species, all of which are living along the coast, is undoubtedly of very 

 late date, almost recent enough to be called a raised beach. It is the 

 only deposit of large extent without some extinct species known on the 

 mainland, San Nicolas Island, eighty-seven miles farther west, being 

 the only locality apparently as recently elevated. 



(2) Pliocene Deposit.— The great shell-bed at El Toro Station, 600 

 feet higher, appeal's to be an older uplift, and will probably prove to 

 contain enough extinct species to be called Pliocene, though such have 

 not been identified on account of the bad condition in which they are, 

 the lime being mostly dissolved out of the upper layers. Similar beds 

 exist farther south and north. 



(3) Miocene Deposits. — The remaining foothills west of Santiago 

 Caiion seem to be decidedly of Miocene age, with numerous character- 

 istic fossils. At one point only, about three miles above El Toro, 

 Alisos Creek has cut down into the Cretaceous formation, and there I 

 found the characteristic Cretaceous fossils given (in part) as from the 

 Santa Ana Mts., in the Catalogue of 1888. (Three Tertiary species 

 from beds above them are also given there.) A portion of them were, 

 however, obtained by Professor Davidson's Coast Survey assistants, on 

 or near the summit of Santa Ana Peak (Mt. Downey), about 1871. 



(4) Eocene {or Cretaceous B). — While only one out of twelve species 

 obtained in the collections of 1872-1874 could be doubtfully referred 

 to this formation, Dr. Bowers' collection contains twelve or more. As, 

 however, he did not observe any line of division separating the strata 

 containing them from the Cretaceous, it is doubtful whether they can 

 be as well distinguished in these uplifted and disturbed strata, as in 

 those at San Diego, where they lie nearh' horizontally on inclined 

 Cretaceous. 



(5) Cretaceous (A). — These beds, apparently rich in fossils, seem to 

 contain species from several divisions older than the so-called " Chico- 

 Tejon" groups, but there is a very small proportion of Ammonitidffi, 



