Gkol— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. II 



complete classification of the series can be made, in which 

 there shall appear its diversit}^ and complexity, as well as 

 its unity. It is accordingly the aim to give here what are 

 thought to be the most natural divisions of the series, which 

 shall recognize both its physical and faunal changes in their 

 more important phases, and call attention also to the devel- 

 opment of its fauna in geological time. Third, it is possible 

 to correlate with more precision than has yet been done the 

 various members of the California section with those of 

 neighboring basins, neighboring American provinces, and 

 other countries bordering the Pacific, if not also with the 

 Atlantic and Indian oceans. Furthermore, many new and 

 interesting fossil forms occur in the Cretaceous of California 

 and Oregon, and many types whose close affinities with east 

 Asiatic and Atlantic species have not yet been sufficiently 

 recognized. 



Probably no other formation is so favorable as the 

 Cretaceous for the study of the distribution and historical 

 development of the faunas embraced within its limits. The 

 study of these problems may easily lead to the recognition 

 of important changes that have taken place in the physical 

 geography of North America and of the Pacific basin. In 

 this connection it may be said that the limitations that are 

 at present accepted for the different divisions of the Creta- 

 ceous series of California may be subject to some important 

 alterations, and that the closer discrimination of horizons 

 is both desirable and possible. 



The physiography of California and Oregon, and perhaps 

 of other West Coast regions during the Cretaceous, which 

 ought to be connected with a study of this period, is not 

 yet sufficient!}^ recognized, although of more than ordinary 

 interest. Not only is the general shore-fine of the Creta- 

 ceous ocean approximate!}^ known, but the principal inlets 

 that indented the shore of that time may be clearly shown. 

 Something also of the drainage and configuration of the 

 surface may be inferred. 



