RESUME OF LITERATURE. 95 



constitute a lower series and are overlain by an upper one of reddish-brown 

 conglomerate sandstone not far from 2,500 feet thick. Large fragments of granite, 

 gneiss, and quartzite prevail, but with them are some of sandstone and limestone. 

 "This part of the section bears close resemblance to the upper division of the 

 Carboniferous series seen on the Eagle River of central Colorado." No Triassic 

 was found in this area, the Carboniferous underljdng the Dakota throughout. 



It maybe added that neither has the "Triassic" series or "Red Beds" been 

 reported by any of the geologists who have written of the Sangre de Cristo region, 

 nor is it represented upon the Hayden maps. Its absence in this area is in agree- 

 ment with its absence over the southern part of the South Park region, the southern 

 part of the Elk Mountain region, and the southern part of the Front Range region, 

 where the "Red Beds" apparently belong in the Fountain and not in the Wyoming 

 formation. At the same time Hills remarks that a small thickness of brick-red 

 sandstone occurs in the Sangre de Cristo Range above the Arkansas sandstone and 

 in the Walsenburg quadrangle above the Badito formation. Yet, though the posi- 

 tion and color of this bed rather suggests the "Triassic," it can probably be 

 provisionally regarded as part of the Arkansas sandstone. 



No fossils are cited from the Carboniferous, so that conclusive evidence is 

 lacking as to the presence or absence of the Mississippiau limestone in this section. 

 The Hayden atlas, it is true, represents an area of Lower Carboniferous at and about 

 Trinchera Peak, and this division frequently contains beds of Mississippian age, but I 

 am disposed to think that the Mississippian is really wanting, if not at the Trinchei'a 

 Peak locality, at least from Stevenson's section, first, because there is nothing in it 

 comparaVjle to the massive and persistent Leadville limestone, unless it be the highest 

 limestone of the section, and, second, because the limestones of Sangre de Cristo Pass, 

 which are probably the equivalents of those in Stevenson's section, appear from their 

 fossils to be Upper Carboniferous. It would thus appear probable that the whole of 

 the Carboniferous section is of Peunsylvanian age" and to be compared with the 

 Maroon conglomerate of the Crested Butte section and with the Weber grit and 

 Upper Coal Measures of the Leadville section. The two divisions of Stevenson's 

 section are indeed comparable to the two divisions of the original Maroon. The 

 resemblance in both lithology and thickness in the case of the upper divisions is 

 rather striking. The lower one in Stevenson's section, however, though not unlike 

 the other lithologically, is much thicker. But with indications of an unconformity at 

 the base of the Maroon, and a possible time break between its two divisions, disparity 

 in the thickness of the lower portion in different areas would not be surprising. 



a This appears to be certainly the case in Lee's section west ol Trinidad, but it is possible that here, as along the 

 Front Range, the Mississippian limestone and earlier Palezoic formations may underlie the Arkansas sandstone in 

 disconnected patches. 



