} 



320 E. M. KIKDLE RECONNAISSANCE OF PORCUPINE VALLEY 



Carboniferous series lias been faulted out of sight. The downthrow 

 would seem to be 1,000 feet or more. 



It might be assumed on a priori grounds that in a region where folding 

 such as has been described prevails, faults, if present, would be _of the 

 thrust tj-pe. Those which are known, however, are all normal faults. 

 Had faulting occurred at the time of folding, the resulting faults would 

 undoubtedly have been thrust faults. The normal faults which are 

 present we must conclude, then, were developed either before or subse- 

 quent to the folding. Their origin is believed to have been of subsequent 

 date. 



Stkatigeapht and Faunas 

 pre-ordovician series 



The oldest rocks exposed in the Porcupine Eiver section are found in 

 the vicinitj^ of the International boundary. The distribution of these 

 older beds and the later terrains is shown on the map, figure 1. This 

 series is well exposed in the steep slopes and cliffs facing the river at Xew 

 Eampart House and outcropping continuously for 6 or 7 miles below 

 there. It is composed largely of thin-bedded and very fine-grained 

 quartzites, which are bedded usually in thin strata 1 to 6 inches thick. 

 Intercalated with the quartzites are considerable beds of black shale and 

 limestone and thin beds of dolomites. The nearly universal color of the 

 quartzites is light gray or white, which gives them a strong resemblance 

 to limestones. Occasional beds occur, however, which are specked with 

 brown, and one 30-foot bed of dark-brown sandstone was observed in the 

 river bank at Xew Eampart. Sulphide of iron is present in some of the 

 beds, as is indicated by the accumulation of fihns of sulphur on protected 

 rock faces. Where exposed to weathering the quartzite beds disintegrate 

 to a fine white or cream-colored impalpable powder. This powder covers 

 all the steep slopes where vegetation is absent, giving the appearance of 

 great marl or clay beds at a little distance. 



The black shales and slates occur usually as thin carbonaceous films 

 alternating with limestone bands one-half inch to 3 inches thick. The 

 presence of the limestone, although it comprises the bulk of these bed^, 

 is not evident in the weathered exposures of steep slopes, where the in- 

 tensely black shale or slate fragments are apt to conceal the light-colored, 

 thin limestone strata, giving the whole the appearance of a shale or slate 

 formation. Below ISTew Eampart House 1 mile a set of these black beds 

 500 or 600 feet thick is intercalated in the quartzite series. The latter 

 series is well exposed in the gorge of the small stream entering the For- 



