BBSUME OF LITERATURE. 99 



they come in contact with the Harding sandstone. Beyond the eastern line of the 

 quadrangle thej' are usually found to abut against granite or gneiss. 



The Fountain formation is succeeded by the Morrison formation, and the Morri- 

 son by the Dakota. "The Morrison strata rest with apparent conformity upon the 

 Fountain grits in the main foothill section, but in Twelvemile Park and in the higher 

 plateau region to the north they lie directly upon granite. There is thus a great 

 stratigraphic break between the Morrison and the Fountain formations. An exten- 

 sive vertebrate fauna found in the Morrison formation shows that its age is post- 

 Paleozoic. " " 



The Paleozoic series, then, in the southern part of the Pikes Peak quadrangle 

 has at its base a slight development of Cambrian sediments, too thin to be mapped, 

 upon which rest in succession the Manitou limestone, Harding sandstone, Fremont 

 limestone, Millsap limestone, and Fountain formation. The Manitou, Harding, 

 and Fremont formations represent Ordovician time, the Millsap and Fountain, Car- 

 boniferous. The age of the Fountain formation is determined only by analogj'^; that 

 of the other formations rests upon paleontologic evidence. Unconformities occur 

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

 limestone and the Millsap limestone, and between the Millsap limestone and the 

 Fountain formation, while still a fourth and verj' important one is found between 

 the Fountain formation and the overlying Mesozoic. 



The section in the northern, or Manitou Park, Paleozoic area is similar to that 

 in the southern one, except that the Harding sandstone, the Fremont limestone, and 

 the Millsap limestone are lacking in it. 



In connection with the field work leading up to the Leadville monograph, Whit- 

 man Cross made a visit to the exposures in Manitou Park, on the eastern side of the 

 Front Range.'' 



"Although only 50 to 75 miles distant from the Mosquito Range exposures, the 

 beds were found to vary so much in lithological composition that it was impossible 

 to obtain an exact correspondence of horizons. The purely siliceous beds at the base 

 are much thinner thau in the Mosquito Range, the greatest thickness found being 

 50 feet. They are succeeded by calcareous sandstones and shales of variegated colors, 

 red prevailing, which pass up into white or drab limestones, sometimes containing 

 chert secretions and alternating with shaly beds, with an aggregate thickness of 

 about 200 feet. These beds may be considered as the equivalents of the Lower 

 quartzite and White limestone of the Mosquito Range." 



Fi'om the east bank of Trout Creek (Bergens Creek on the Hay den map), 2 miles 

 below the hotel, Mr. Cross obtained fossils which have been identified by Mr. C. D. 

 Walcott, as follows: 



From reddish-brown sandstone, 45 feet above the Archean. 



o Much of the preceding digest is stated iu the words of the original. 

 1>V. S. Geol. Surv., Mon., vol. 12, 1886, p. 62. 



