EASTERN COLORADO 557 



quartzite, and sometimes they overlap on the granite and gneiss. The 

 overlying formation, separated by unconformity generally, is the Millsap 

 limestone of Lower Mississippian age. 



In the region about Canyon City the Ordovician is represented by the 

 Manitou limestone, Harding sandstone, and Fremont limestone. These 

 have been described in detail by Mr C. D. Walcott* mainly in connection 

 with the occurrence of fish remains, and by Dr Whitman Cross in 

 describing the region northeast of Canyon City which is- included in the 

 Pikes Peak folio. I have made a detailed examination of the outcrops 

 west and southwest of Canyon City. 



MANITOU LIMESTONE 



This limestone is extensively exhibited in Oil Creek valley, Garden 

 park, a few miles north of Canyon City, where it consists of fine grained 

 pink or reddish, dolomite less than 100 feet thick. It also occurs in the 

 Manitou region, where it contains Ophileta, Camerella, and other char- 

 acteristic Ordovician fossils. It often is underlain by cherty, reddish 

 limestone and sandy beds containing Cambrian fossils. 



HARDING SANDSTONE 



This formation consists mainly of fine, even grained, granular sand- 

 stone in alternating bands of light-gray and pinkish or variegated colors, 

 with a few bands of dark-red or purplish sandy shale, having a maximum 

 thickness of about 100 feet. The lower part is sometimes calcareous and 

 develops into a thin, fine grained dolomite. This formation contains the fish 

 remains at the Canyon City locality. In Garden park the sandstone rests 

 with apparent conformity on the Manitou limestone, but to the southeast 

 it overlaps on the basal sandstone, and near Canyon City on the gneiss, 

 as shown in figure 2, plate 78. At Canyon City the formation is 86 feet 

 thick, and consists of gray, reddish, and purplish-brown sandstone and 

 shales, with many fossils of early Trenton age. A small outlier of sand- 

 stone, apparently of this formation, underlying the Millsap (Carbon- 

 iferous) limestones in the slopes west of Beulah, is mapped by Gilbert in 

 the Pueblo folio. 



FREMONT LIMESTONE 



Overlying "the Harding sandstone with apparent conformity there 

 occurs a bluish-gray or pinkish dolomite of uneven grain, sometimes 

 arenaceous, which gives rise to very rough weathered surfaces." Its 



* Bull. Geol. Soc. Am., vol. 3, pp. 153-167. 



LI — Bull. Geol, Soc. Am., Vol. 17, 1905 



