EASTERN COLORADO 559 



thickness in Garden park is about 100 feet, but increases southward to a 

 maximum of 270 feet near Canyon City, partly through the development 

 of an upper fossiliferous member. In Garden park it is characterized 

 especially by the coral Holy sites catenulatus, and also contains a molluscan 

 fauna like that of the Upper Trenton in New York. It appears to be 

 restricted to a small area in Garden park and vicinity and a narrow out- 

 crop extending southward past Canyon City. 



These formations all disappear a short distance southwest of Canyon 

 City by overlap of later deposits and faulting, but two small outlying 

 areas of Harding sandstone overlain by Fremont limestone were found, 

 one near the road 4 miles southwest of Canyon City and another at the 

 foot of the mountain on one of the branches of Chandler creek, 7 miles 

 nearly due south of Canyon City, the latter containing fish remains. 



RELATIONS IN GARDEN PARK REGION 



'he Ordovician limestones and sandstones are extensively exposed on 

 the west side of Oil creek, north of Garden park, a few miles north of 

 Canyon City. At the base is Manitou limestone with a basal cherty and 

 quartzitic portion of Cambrian age lying on the granite and gneiss. Next 

 follows the Harding sandstone, surmounted by long slopes of Fremont 

 limestone. So far as observed, this sequence is general for an extensive 

 area about Garden park. In portions of the area faults cut out some, or 

 all, of the beds. On the granite slopes east of Oil creek numerous small 

 outliers occur. The Manitou limestone is here 100 feet thick, and con- 

 sists of fine grained pink or reddish dolomite with Ordovician fossils. 

 Cherty limestone at the base yields fragments of the trilobite Ptychoparia 

 of Cambrian age. The Harding limestone consists of fine and even 

 grained saccharoidal sandstone in alternating beds of light-gray or pink- 

 ish and variegated colors, with a few bands of dark-red or purplish sandy 

 shale. The maximum thickness is about 100 feet. The lower part is 

 sometimes calcareous and locally develops into a thin, fine grained dolo- 

 mite. It is succeeded with apparent conformity by the Fremont limestone, 

 which is a bluish gray or pinkish dolomite of uneven grain, sometimes 

 sandy, weathering to very rough surfaces. Its thickness is about 100 feet, 

 and it is especially characterized by the occurrence of chain coral (Haly- 

 sites catenulatus) , which often occurs in masses 2 feet in diameter. It 

 also contains other fossils of Upper Trenton age. 



The Fremont limestone gives rise to long sloping plateaus on the west 

 side of Oil creek north of Garden park. At the north end of the park the 

 Fremont limestone is overlain by 30 feet of Millsap limestone in a narrow 

 outcrop about iy 2 miles long. 



