106 CARHONIKKKOUS KORMATIONS AND KAUNAS OF COLORADO. 



uiuli'rlyinK' ji''''>"itif i"t)*'l^><, that tlio Front Range, dm-injj^ the supposed Triassic period, 

 formed a vast sliore lino, and tliat the sediments of the lied Beds were deposited upon 

 the base against the sides of the granitic range." It seems probable, indeed, that 

 this coiiditidii lias been one of periodic occurrence, and that the Front Range repre- 

 sents a line of permanent weakness which has been repeatedly elevated, denuded, 

 and submerged. 



Poale's district for 1873" includes, besides other territory west of this, the 

 Front Range from the South Platte to Colorado Springs. Important detailed 

 sections were made on the South Platte, through Pleasant Park, and at Glen Erie, 

 and four others of almost equal interest were described from Trout Creek. The 

 strata in the Front Range sections are classed as Silurian, Carboniferous, Triassic, 

 Jurassic, and Cretaceous. 



The southern part of the Trout Creek or Manitou Park Paleozoic area is included 

 in the northern part of the Pikes Peak quadi-angle, which in its southern portion 

 embraces a larger area of the Paleozoics about Canj^on. In the section given 

 bj' Cross for that portion of the Manitou Park area included in the Pikes Peak 

 quadrangle, the Ordovician, as we have just seen, is represented only by the 

 Manitou limestone, and the Carboniferous by the Fountain formation. The four 

 sections given b}' Peale deal onlj' with the strata which underlie the Red Beds, or 

 Fountain formation, which are mapped as Triassic, and therefore only with the 

 Cambrian rocks and the Manitou limestone. The Millsap limestone apparently is 

 entirely lacking, and the Hayden atlas shows no Carboniferous color in this area. 

 The Cambrian is shown by Peale's sections to be considerablv thicker here than 

 in the Pikes Peak quadrangle. It consists of yellow, purplish, pink, and green 

 sandstones, reaching a thickness in one case of 80 feet, from which Cambrian fossils 

 {Obolus and Lingulepis) were obtained. The Manitou limestone, contains red, 

 white, and pink limestones, attaining in one instance a thickness of 130 feet. A 

 well-characterized Ordovician fauna was obtained from them. 



In the section made at Glen Erie, whose outci'ops are all but connected with 

 those of the Manitou Park area, the best-characterized bed is that numbered 13, which 

 by reason of its fossils, its character, and its position clearly belongs to the Manitou 

 limestone. With it can probably be associated the 26 feet of variegated calcareous 

 beds next below, as indicated by Peale, while the sandstones forming the base of the 

 whole section are probably Cambrian. Above bed 13 follows 279 feet of gray, 

 purplish, and 3'ellowisli limestone, unfossiliferous and not otherwise differentiated. 

 From the fact that there is no fossil evidence indicating that any portion is of 

 Carboniferous age, and that the Millsap limestone, so far as is known, is absent from 

 the Manitou Park area, this entire thickness may be regarded as belonging to the 



iiD. S. Geol. Geog, Surv. Terr., [Seventh] Ann. Rept., lor 1873, 1874, pp. 193-273. 



