EESUME OF LITERATURE. 109 



sandstones and conglomerates, which appear to be perfectly conformable with the 

 fossiliferous sei'ies. Thej' are colored irreg-ularly in various shades of red and gray 

 to an extent which gives the series a conspicuous mottled appearance. The gray 

 predominates near the base. From thence upward the red becomes prominent and 

 the series passes graduallj" into the so-called 'Trias' — the Red Beds. No line of 

 demarkation was found between this formation and the Trias.'' 



The fossils mentioned, together with a series collected bj^ Whitman Cross, are 

 discussed in the paleontologic portion of the present paper. Of the Cai'boniferous 

 age of this fauna there can be no doubt, and it can safely be referred to the Lower 

 Carboniferous. The upper portion of Lee's Carboniferous section he correlates, 

 by stratigraphj' and lithology, with the Fountain beds of the Pikes Peak quad- 

 rangle, and the opinion seems to be entertained that by this series, together with the 

 typical Red Beds into which it graduates, the Carboniferous and Permian, as well as 

 the Triassic periods are represented. A nearly vertical series east of the park 

 undoubtedly belongs to the Red Beds proper (Lee). 



The relation of the beds in Lee's map is such as to indicate an unconformity 

 b}- overlap of the Red Beds, which seem to be the Wyoming formation of the 

 Denver Basin area, upon the supposed equivalent of Cross's Fountain formation. 



Peale's section in Perry Park, or Pleasant Park, as it appears to have been called 

 at that time, must include the same strata described by Lee. Peale refers. all the 

 lower part of the section down to the granite to the Carboniferous, as does Lee, but 

 I inclined to identify as Cambrian the sandstones at the base of his section, founding 

 the opinion upon the resemblance in lithology and position to strata in other near-by 

 sections from which he reported Cambrian fossils. Hayden also suggests the possi- 

 bility' of the view held by me. All the lower part of Peale's section below the Red 

 Beds seems to be equivalent to Lee's Carboniferous (except the part supposed to 

 represent the Fountain formation). The fossiliferous limestone at the top in each 

 case is the Millsap limestone. Of this, Peale cites 9 feet, and Lee 10 to 15 feet. 

 As occurring beneath the limestone, Peale mentions 105 feet of red, white, and 

 purplish sandstones, while Lee finds iO feet of red and gray sandstones. The 

 differences so far noted are not important, and doubtless result from the two sections 

 not having been made at the same exposures. The sandstones in Peale's section, 

 however, rest on granite, while in Lee's section one would infer that they were 

 underlain bj- the Ordovician limestone already referred to. The Ordovician lime- 

 stone, however, appears not to have been found in the Castle Rock quadrangle, but to 

 have occurred with the red Cambrian {'i) quartzite south of the area mapped by Lee. 



Several interesting possibilities present themselves. The most probable is that 

 the sandstones under the Millsap limestone are really not Carboniferous, but Cam- 

 brian, and that the place of the Ordovician limestone is not below but above them, 

 the limestone itself having been cut out by the erosion by whicn the Millsap lime- 



