WALCOTT.] 



SUMMARY COLORADO. 



353 



From the east bank of Trout Creek, in Maniton Park, Mr. Cross ob- 

 tained fossils from a reddish brown sandstone, 45 feet above the 

 Archean, among which an elongate form of Lingulepis, .illied to L. pin- 

 naformis of the Potsdam sandstone of Wisconsin, occurs. From the 

 red calcareous sandstones, alternating with white limestone, 105 to 122 

 feet above the Archean, the fauna is the type of that of the lower por- 

 tion of the Lower Silurian (Ordovician). 



Two sections measured on Trout Creek by Dr. A. C. Peale gave the 

 following results: 1 



No. 5. 



1. Granitic 



2. Yellow sandstone 



3. Pinkish sandstone 



4. Dark, purplish brown sandstone 



5. Green sandstone 



6. Blood-red calcareous sandstone. 



7. Pink limestones 



Feet. 



65 



13 

 3 



60 



" Beds No. 6 and 7 are fossiliferous and belong in all probability to 

 the Quebec group, while the sandstones below are Potsdam." A list 

 of fossils is given as coming from No. 7 which indicates a grouping of 

 Cambrian and Silurian (Ordovician) genera unknown elsewhere. 



Dr. F. M. Endlich's synopsis of the rocks of the Potsdam group found 

 in Colorado sums up all that was known to him of the principal local- 

 ities and the character and thickness of the strata. Seven localities 

 are mentioned, as follows : a 



© 

 o 

 a 



o 



ft 



Lime Creek 



Eagle River 



Four-mile Creek 



Trout Creek 



North of Mount Ouray . 

 Near Canyon City 



^Glen Eyrie. 



White sandstone and quartzite 



White q uartzites 



Red and pink sandstones and quartzites... 



Yellow and pink sandstones 



White and pink quartzites 



Variegated micaceous and calcareous sand- 

 stones. 

 Red sandstones and quartzites 



Average thickness of strata 



Feet. 



250 



300 to 400 



160 



80 

 200 



40 



180 



That the Upper Cambriau zone is represented is fairly well proved 

 by the Mosquito Range section and that of Trout Creek of the Colorado 

 Rauge, and it is very probable that the sandstones correlated with the 



1 Report of A. C. Peale, M. D., Geologist of the South Park Division. U. S. Geol. Surv. of the Terr., 

 7th Ann. Rep., 1874, p. 208. 



2 Report of F. M. Endbch, Geologist of the White River Division. TJ. S. Geol. Surv. of the Terr., 10th 

 Ann. Rep., 1878, p. 130. 



Bull. 81 23 



