PEOQUOP EANGE. 507 



minute flakes of mica. The mica consists of both the dark magnesian 

 biotite and white muscovite. 



Under the microscope, Zirkel detected numerous crystals of zircon, 

 which he has shown to be so abundant in the Archaean series of gneisses 

 and schists along the Fortieth Parallel; and the biotite plates, but not the 

 white mica or quartz, contain exceedingly minute microscopical needles, 

 which he suggests may possibly be referred to the same mineral. Other 

 beds are somewhat coarser in texture, less compact on account of the quartz- 

 grains being larger, and the dark mica more abundant, with broader plates, 

 rocks more closely related to what are usually designated as schists. The 

 observed area of these beds is exceedingly small, and has not been indicated 

 on the geological map. It is possible that more careful field-study would 

 discover a number of such areas and would indicate clearly a much larger 

 Archaean territory along the base of the mountain, and perhaps show an 

 important Archaean foundation for the striking uplift of Palaeozoic strata. 



The entire northern end of the Pepquop Eange would appear to con- 

 sist of Weber Quartzite, overlaid by Upper Coal-Measure limestone. No 

 estimate of the thickness of this quartzite was made, but it is at least 

 several thousand feet, forming many of the higher summits and spurs. In 

 places, it is capped by fragments of limestone, while, in others, the overlying 

 rock may show a very great development. Directly south of Peoquop 

 Pass rises a series of limestone hills with a strike varying from north 30° 

 to 40° east, and dipping to the northwest at an angle of about 40°. There 

 must be exposed here about 2,000 feet of limestones, which are conformably 

 underlaid by heavy masses of quartzite, which are supposed to continue to 

 the eastern foot-hills. The same masses of limestone which dip northwest 

 curve around, and form the hills on the west side of the range. In the 

 limestones south of the pass, not far above the quartzites, were obtained 

 Carboniferous fossils, among which were the following: 



Produdus semireticulatus. 

 Spirifer cameratus. 

 Discina, sp. undet 



On the east side of the range, Squaw Creek from the summit to the 



