hayden.] GEOLOGY OF THE ELK MOUNTAINS. 57 



broken in every direction. The aggregate inclination, however, is 

 always to the northeast. This great mass of Cretaceous beds were 

 influenced by the operations of two quite distinct elevatory forces which 

 probably acted synchronously, so far as forces so different could act. 

 To the eastward the long ridges of the Triassic and Carboniferous Red 

 Beds extend down to the west from the axis of the Sawatch range, cut 

 into deep canons, the waters of which flow into the Grand Eiver. 

 These Red Beds were elevated by the Sawatch range, while the Roaring 

 Fork flows through a sort of anticlinal valley between the axis of the 

 Elk and the Sawatch Mountains. These Cretaceous beds form a sort of 

 an island or basin between these great axes, and therefore lie in the syn- 

 clinal. It is by means of the more modern beds, as the Cretaceous group, 

 that the anticlinal character of the mountain range is more clearly seen. 

 The Triassic and the Carboniferous beds extend over the axis of the 

 range, while the granite nucleus makes its appearance ouly in limited 

 areas, as at Sopris, Capitol, Snow Mass, and White Rock peaks. Be- 

 tween Capitol and Sopris peaks there is a long distance where the Red 

 Beds form the axial ridge entirely, and seem to hold for the most part 

 a horizontal position. On the map the Red Beds or Triassic and the 

 Carboniferous groups are thrown together, from the fact that we found 

 very great difficulty in separating them. Not only is there no apparent 

 break in the sequence of the strata, but they are- so mingled together 

 in the uplifts and overturnings that it would have required more de- 

 tailed study of the range to separate them entirely than we were able 

 to give at that time. Co-extensive with the narrow belt of the Dakota 

 group, is a light band which represents the Jurassic group. Neither of 

 these formations is ever exposed over large areas, usually only in out- 

 cropping edges along the margins of the mountain, or in the sides of the 

 caiions. The Silurian group, so far as it is known in this region, always 

 rests directly on, the granites, whether igneous or metamorphic, and is, 

 therefore, confined mostly to an outcropping belt around the granite 

 areas. On the west and southwest sides of the axis the Cretaceous 

 group appears again, extending far beyond the limits of the map. Its 

 relations to the axis are such as to show plainly that, like the older 

 formations, it formerly extended in an unbroken mass across the area 

 of the Elk range. There can be no doubt of the original continuity of 

 the entire mass of the sedimentary strata. North and west of Sopris 

 Peak the country slopes off toward the Colorado River, and the sur- 

 face is gashed deeply with the gorges of the streams which cut through 

 the Cretaceous beds, oftentimes into the older groups. The Cretaceous 

 strata, however, predominate. 



In the annual report for 1873, the tremendous effects of erosion, as 

 shown on the west side of the Elk Mountains, were described in detail. 

 These effects are displayed even on a still grander scale on the east side 

 of the range. The gorges or canons cut by Castle and Maroon Creeks 

 and their branches, are probably without a parallel for ruggedness, 

 depth, and picturesque beauty in any portion of the West. The great 

 variety of colors of the rocks, the remarkable and unique forms of the 

 peaks^ and the extreme ruggedness, all conspire to impress the beholder 

 with wonder. The illustration, given in the northeast cbrner of the 

 map, of Castle group is a type of the scenery at the heads of these 

 streams. We here see from 3,000 to 5,000 feet of stratified rocks lifted 

 up vertically so that the beds are horizontal, or nearly so, presenting to 

 the eye, by the eroded forms, a wilderness of pyramidal cones whose 

 summits rise to a height of 13,000 and 14,000 feet. The sides of the 

 canons are vertical or nearly so, displaying a continuous section of the 



