42 GEOLOGICAL SURVEY OF THE TERRITORIES. 

 THE CARBONIFEROUS GROUP. 



The Carboniferous group is a little more persistent, and yet this seems 

 to be wanting over extended intervals, unless a portion of what have 

 been called the Eed Beds is of this age. This group is exten- 

 sively exposed along the flanks of the mountains, 100 to 150 miles 

 north of Cheyenne, as was shown in the annual report of 1870. It 

 seems, however, to diminish somewhat in force, and to contain 

 comparatively few fossils in its southern extension, until we reach 

 Canon City. From thence southward into New Mexico it increases 

 again in thickness and importance, and yields an abundant supply of 

 its characteristic fossils. I have no positive information of the dis- 

 covery of any well-marked Carboniferous fossils from the line of the 

 Union Pacific Eailroad to the vicinity of Canon City, although strata 

 supposed to be of that age are exposed in a few localities. On the 

 small map of "Colorado Springs and vicinity," a light band will be 

 seen between the Silurian on the west and the Red Beds or Triassic on 

 the east, which represents a peculiar group of strata not observed else- 

 where on the eastern slope, but resembling very closely a series of varie- 

 gated beds, described by Dr. Peale, in the annual report for 1873, in 

 the valley of Eagle River, which yielded well-marked Carboniferous 

 types. This group of strata is composed of variegated beds of sand- 

 stones of various textures, alternately with layers of arenaceous clay. 

 The entire thickness was estimated at about 1,000 feet. It is most 

 probable that these beds are of Carboniferous age. 



From Colorado Springs the Carboniferous group is not conspicuous 

 at any locality, and for a great portion of the way is not seen at all, but 

 at Canon City and Wet Mountain Valley the limestones and sandstones 

 contain numerous fossils, both animal and vegetable. From the Wet 

 Mountain Valley, which is but a short distance south of Canon City, 

 Mr. R. N. Clark collected specimens of vegetable remains from the Car- 

 boniferous beds, which were submitted to Professor Lesquereux. He 

 detected jStigmaria fucoides, Brgt., showing scars of surface with stems 

 and leaves attached ; mold of the internal surface of the cylinder of a 

 Catamites ; small specimens of a new species of Gordaites, resembling by 

 its nervation Gordaites principalis. An abundance of invertebrate fos- 

 sils have been discovered in this group which have not yet been studied. 



THE RED BEDS OR TRIASSIC GROUP. 



The Red Beds or Triassic group is very persistent, and if absent at all, 

 only at very short intervals. No organic remains have yet been found 

 in this group by the members of the survey under my charge, yet, for 

 various reasons, we have assumed the red sandstones to be of Triassic 

 age. It is barely possible that a portion or all of the group is of Juras- 

 sic age. Yet Professor Cope is of the opinion that he has discovered 

 evidence in New Mexico of its Triassic age. The history of this group 

 is still obscure, and remains as one of the problems to be solved by 

 more extended and more thorough explorations. Geographically, it is 

 one of the most widely distributed formations in the West. From the 

 northern boundary to the southern line and east of the Wasatch range 

 in Utah, this red formation make's its appearance wherever a mountain- 

 range is elevated so as to expose the various sedimentary groups. The 

 evidence indicates that it extends without any important interruption 

 over the broad area as defined above. This group is generally admitted 

 to be in part, or entirely, of Triassic age, and I have always so regarded 



