240 GEOLOGICAL SURVEY OF THE TERRITORIES. 



A few local disturbances occur, but besides those only the great anti- 

 cliual axis is an object of interest. Although the Cretaceous beds of 

 the southern and western portion have the same general direction of 

 dip as the older ones, several localities have furnished evidence that 

 the disturbances affecting the Devonian and Carboniferous must have 

 occurred before the deposition of the Cretaceous. It is possible that 

 to this fact, to the higher relative position at the time, the absence of 

 Triassic and Jurassic beds may be attributed. 



Eegarding the different members of the older sedimentary formations 

 much might be said about their mutual affinities. The highest Devonian 

 has a decidely Carboniferous aspect, while, on the other hand, the lowest 

 Carboniferous shows affinities to the Devonian.* I have considered it 

 best to draw the line of distinction there where we have character- 

 istic fossils to aid discrimination in the future. Of the red sandstone 

 referred to the Carboniferous mention has often been made in the pre- 

 ceding pages. Based mainly upon stratigraphical evidence, which, it 

 is true, is supported by .meager paleontological proof, I regard that 

 series of sandstones as a member of the Upper Carboniferous formation. 

 It is, so far as I am able to determine, the same that in 1873 I distin- 

 guished as Arkansas sandstone. 



During the coming field-season (1875) I hope to see more of this group, 

 and may succeed in establishing its age beyond doubt. 



Some doubts have arisen as to the classification of the Cretaceous beds 

 in the southern portion, along the Animas. Inasmuch, however, as I 

 have not yet seen the entire series there, and will probably have occa- 

 sion to do so during the next field-season, I shall postpone the dis- 

 cussion of this subject. 



* Compare : Report United States Geological and Geographical Survey, 1873, page 341. 



