RESUME OF LITERATURE. 91 



in 1873 distinguished by the name of Upper Carboniferous (if, indeed, the beds so 

 designated really occupied the position ascribed to them), would indicate that the 

 southern portion of the Sangre de Cristo Range had been the scene of severe post- 

 Carboniferous erosion, though doubtless to the unconformity which preceded the. 

 deposition of the Arkansas sandstone may be ascribed an important share in the 

 influences that produced this difference in bulk. 



Endlich reports no Triassic in the Southeastern district, except at the southern 

 end of the Wet Mountains. To these exposures I shall refer in connection with the 

 Front Range region. 



In lS7i was published Ruffuer's report upon a reconnaissance in the Ute couiitry " 

 made the year previous. The map accompanying the report covers an extensive 

 territory, extending from the thirty-seventh parallel on the south to north latitude 

 39^ 30', and from 105= 30' west longitude on the east to 108° on the west. The 

 primary object of the expedition was not geologic, but two geologists in the persons 

 of F. and L. Hawn accompanied it, and their accounts form Appendix B (pp. 59 to 

 , 88) of the general report. The identification of the different outcrops described 

 with the recognized Paleozoic formations of Colorado is in many cases difficult or 

 impossible because of the brief mention made of them, but in several instances 

 the citation of Carboniferous faunas removes all doubt with reference to formations 

 of that period. The geologic observations so far as thej" concern this resume fall 

 into the San Juan, Elk, Sangre de Cristo, and Front ranges. These accounts add 

 little to the subject, on account of the more detailed character of subsequent work 

 in the same areas, and the interest which attaches to them is largelj- historical. 

 In the earlier portion of the work, which is devoted to a general description of the 

 route, not infrequent reference is made to the occurrence, character, and even thick- 

 ness of the rocks observed, but with these I have not concerned myself, dealing 

 onlj' with the descriptions in the geologic reports. 



In the Sangre de Cristo Range the chief line of observation was the road 

 between Pueblo and Fort Garland bj' the way of Sangre de Cristo Pass. Mention 

 is made of the Carboniferous limestones and brown sandstones (p. 61) of Sangre de 

 Cristo Pass, and from the former are cited CyathophyUum sp. , Productus eqidcostatus, 

 Prodiictus semireticulatus, Productus cwfl, Spirifer cameratus^ Spiriferina Tcen- 

 tuckyensis^ and Seniinnla suhtilita. This is one of the earliest accounts* that I 

 have found of this occurrence of fossiliferous strata, though authors have several 

 times made subsequent raention of it. 



Carboniferous rocks appear to have been found also at the extreme northern 

 end of the range, and it is possible to recognize as the Leadville limestone a bed 



a U. S. War Dept., Rept. Reconnaissance Ute Country in 1873, by RufEner, Washington, 1874, pp. 1-101. 



h Hayden found these fossiliferoas beds as early as 1869 (see V. S. Geol. Survey Terr., Ann. Rept. for 18(i7, 1868, and 

 1869, 1873, p. 175). The fossiliferous Carboniferous beds of the Sangre de Cristo Range are also mentioned by Cope (p. 64, 

 Ann. Rept. Wheeler Survey for 1875), but in a very cursory manner. 



