RESUME OF LITERATURE. 117 



bed is of Ordovician age. There seem to be no traces of the Silurian and Devonian 

 groups. 



Comparing this section with that in the Pikes Peak quadrangle near by, we find 

 both the Harding sandstone and the Fremont limestone recognized as such, Cross 

 having adopted the names from the Canyon exposures. Bed la of Walcotfs section 

 rests directly upon gneiss and schist, while in the Pikes Peak quadrangle, beneath 

 the Harding sandstone, is found another limestone formation, named the Manitou 

 limestone, and an inconsiderable thickness of Cambrian. The Cambrian and part of 

 the Ordovician, therefore, seem to be missing in the Can3^ou section. 



The propriety is somewhat doubtful of including in a single formation beds of 

 geologic age as diverse as Ordovician and Carboniferous, and Cross has therefore 

 distinguished the Carboniferous portion of the original Fremont under the name of 

 the Millsap limestone. 



In the third volume of the Wheeler Survey is a report by Stevenson, in which 

 the geolog}' of a large portion of Colorado is described." Carboniferous is reported 

 in a number of areas. Neither Silurian nor Carboniferous rocks are recognized 

 along the Front Range, however, and the opinion is expressed that their western 

 outcrop is far to the east of the base of the mountain, deeph' buried under the more 

 recent formations.^ The series of red sandstones and conglomerates which was 

 observed from Golden to the Greenhorn Mountains this author refers to the Triassic. 

 At Beaver Creek, a few miles northeast from Canyon, a thickness of 2,700 feet is 

 ascribed to it. At Manitou a bed of shale and another of limestone were observed 

 at the base of the Triassic, and the suggestion was put forward that they might be Car- 

 boniferous. The Triassic is said to be unconfoi'mable with the overl3ang Jurassic, 

 which is in turn conformable with the Cretaceous. The Jurassic on Oil Creek near 

 Canyon consists of light-colored sandstones and shales, amounting in all to about 

 120 feet, overlying a limestone. 



Stevenson's Jurassic corresponds in geologic position, lithologic character, and 

 thickness with the Morrison formation. His Triassic appears to include in dif- 

 ferent sections now the W^'oming formation, now the Wyoming and Fountain, and 

 again onl}^ the Fountain formation. Beaver Creek, the point at which he records an 

 estimated thickness of 2,700 feet of Triassic strata, is in the extreme southeastern 

 corner of the Pikes Peak quadrangle. His "'Triassic" corresponds in this instance 

 only to the Fountain beds, but as Cross gives this formation a thickness of but 

 1,000 feet, it seems that that assigned to it by Stevenson was overestimated. 



While the "Triassic" of Stevenson embraced in the main only the Rocky Moun- 

 tain Red Beds, in the limestones seen at Manitou it probably includes some Ordovician 

 as well. However, the distribution along the Front Range of the older Paleozoics is 



all. S. Geog. Geol. Surv. W. 100th Mer., Kept., vol. 3, 1875, pp. 303-601. 

 !> Ibid, p. 376. 



