62 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



the foot of the cliffs in Dyer Amphitheater and on West Sheridan, whose 

 matrix of light drab-colored limestone renders it reasonably certain that 

 they were derived from some of the beds of this horizon. The following 

 forms are recognized : Leptena melita and an Orthisina like 0. Pepinensis, 

 which correspond to forms found in the Calciferous ; and the syphon of an 

 Endoceras, which belongs to the Trenton epoch. 



Corresponding beds in Colorado Range. In Order to obtain, for purposes of 



comparison, a section of the Paleozoic beds lying directly on the Archean 

 along the Colorado Range uplift, a visit was made by Mr. Whitman Cross 

 to the exposures in Williams cafion, near Manitou, and in Manitou Park. 

 Although only fifty to seventy-five 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 silicious beds at the base' are much thinner than 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 two 

 hundred feet. These beds may be considered as the equivalents of the 

 Lower Quartzite and White Limestone of the Mosquito Range. Owing to 

 extensive denudation it was impossible in the time allotted to trace a con- 

 tinuous series into well-defined Carboniferous horizons. 



From the east bank of Trout Creek (Bergens Creek on the Hay den 

 map), in Manitou Park, two 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 tbe Arcbean. 



Lingulepix, sp. ? Au elongate form allied to L. pinnmformis of tbe Potsdam sand- 

 stone of Wisconsin. 



From red calcareous sandstones, alternating with white limestone, one hundred 

 and five to one hundred and twenty-two feet above the Archeau. 

 Glytocistites (?). Single plates. | CyrtolHes. 



Lingula, sp. undet. ; probably new. 

 Orthis desmopleura, Meek. 



Ortlwceras, sp. undet.; probably new. 

 Bathyurus simillimus, Walcott (f ). 



Metoptoma, new sp. 



This fauna is essentially the same as that of the upper third of the Pogonip Lime 

 stone of Nevada. 



