ir>4 CARBONIFEROUS FORMATIONS AND FAUNAS (IF CdLoKADH. 



ami shales, ami frDin it an extensive fauna is listed, from whirh llie (■(iiielusion is 

 ilrawii tiiat the formation is of k)\ver Trenton or Black River and Birdseye age. 

 The Fremont limestone series consists of red and purple tine-grained arenaeeous 

 shales, gvny siliceous limestone, compact light-colored limestone, dark reddish ))r()Mn 

 sandstone, and compact light gray limestone, a total of 274 feet. Walcott 

 apparently included here 15 to 30 feet of impure variegated banded limestone with 

 interbedded sandstones and argillaceous beds containing Carboniferous fossils. 

 This. Cross later differentiated and called the Millsap limestone. The fauna of the 

 Fremont is lai'g(> and varied and is compared with the middle and upper Trenton of 

 America, or the Bala of Europe. The fauna of the Harding sandstone is remarkable 

 for its fish remains, associated with a well-marked Ordovician fauna. "With the 

 outcrops near Canyon, at one of which the section quoted from Walcott was made, 

 the Paleozoic area included in the southern portion of the Pikes Peak quadi'angle is 

 essentialh^ continuous. The section in Garden Park, however, includes Cambrian 

 beds, the Manitou limestone, the Harding sandstone, and the Fremont limestone, 

 while only the Harding and Fremont are found at Harding's quarry. Furthermore, 

 the thickness of the Fremont limestone in Garden Park is about 100 feet, but it 

 increases southwai;d, and near Canyon reaches a maximmn of 270 feet. This is 

 partly through the development of an upper and highly fossiliferous member not 

 seen in Garden Park (Cross). 



In the Pueblo quadrangle the Cambrian and the Manitou limestone appear to be 

 wanting, and possibly also the Fremont limestone. The beds referred by Gilbert to 

 the Harding consist of white sandstone and rest upon the Archeau. They are 

 followed in the section by a series of gray and purplish limestones, some 200 feet in 

 thickness, with some shale in the lower part, which Gilbert calls the Millsap lime- 

 stone. Near the middle of the formation was obtained Spirifet' rockymontamts, 

 which is cited also from the Millsap limestone of Garden Park, so that the upper 

 part of the formation at least is Carboniferous. As the Millsap is onlj- 30 feet thick 

 in the Pikes Peak quadrangle, and as the Fremont is 270 feet at Canyon, it is unex- 

 pected to find the former increased to 200 feet at this point and the latter totally 

 absent. Perhaps, therefore, the lower part of Gilbert's Millsap belongs in the 

 Fremont, which otherwise, like the Manitou, has no representative in this area. 



The outcrop of these beds is in the western part of the quadrangle, and includes 

 part of the small area which in the Hayden atlas is represented as Lower Carbonif- 

 erous. Endlich describes these beds as grayish limestone and shale with Carbon- 

 iferous fossils. 



This is, so far as known, the last outcrop of the pre-Carboniferous sedimentaries 

 south of Canj'on along the mountain front. None have yet been found on the east- 

 ern flank oi tne Sangre de Cristo Range, and one detailed section — that made by Lee 



