84 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



EUGEOSYNCLINE 



MIOGEOSYNCLINE 



• OLfCAMPlAK 



MISSISSIP 

 AND OLD 



ORDOVICIAN 



NORTH-CENTRAL 

 NEVADA 

 LAND AXIS 



»00 f 

 i too 



IOOO 



- soo 





PROBABLE NORTH EDGE 

 OF LATE PENN. EMERGE 

 AREA 



NT 



Fig. 6 



strata 

 1955. 



15. Antler orogenic belt of central Nevada showing Mississlppian, Pennsylvanian, and Permian 

 restored to early Wolfcampian time. Section extends from Winnemucca to Elko. Reproduced from Dott, 



accumulated. Wide areas of almost unexplored country in eastern Yukon are 

 presumed to be underlain chiefly by Paleozoic strata, but may also contain 

 rocks of Mesozoic and Precambrian age. In northern British Columbia, where 

 exposed strata are thought to represent much of Paleozoic time, no important 

 disturbance has been recognized. In a number of localities sedimentation and 

 volcanism probably proceeded more or less continuously from late Paleozoic 

 into early Mesozoic time, but in places an interval of uplift and erosion without 

 marked tilting or folding may have intervened. 



A report on the Cassiar Mountains, Finley River district between lati- 

 tudes 56 and 58, and longitudes of 124 and 126, by Dolmage (1928) de- 

 scribes a series of metamorphosed rocks of Carboniferous age. They are 

 "green ash rocks pressed and altered into schists, interbedded with layers 

 of graywacke, felsite, halle-flinta, serpentine, and argillite." Along Takla 

 and Stuart lakes and vicinity the series is made up of limestones, argillites, 

 cherty quartzities, green schists, slates, volcanic flows, tuffs and breccias, 

 and narrow bands of dolomite. Fusulina and other Carboniferous fossils 

 have been found in some of these beds. 



Underlying the Carboniferous series, great belts of schist and quartzite 



occur. Quartz mica schist constitutes about three-fourths of the whole. 

 In many places, the schist grades into quartzite, both of which were de- 

 rived undoubtedly from siliceous sediments (Dolmage, 1928). Such rocks 

 as these are widespread and have been correlated with the Shuswap 

 terrane of southern Rritish Columbia, which now as previously explained, 

 is believed to be made up of rocks of several Paleozoic periods as well as 

 Precambrian. Also some coarse quartzites, quartz pebble conglomerates, 

 and limestones have been likened to the Cambrian strata of the southern 

 Canadian Rockies, previously described. 



The areas of such rocks are shown on the map of Fig. 33.12. A great 

 medial area of Proterozoic (Beltian?) rocks separates the western areas 

 of Carboniferous rocks from the eastern Paleozoic rocks, but whether or 

 not this was a highland in Paleozoic time is unknown. 



SUMMARY OF OROGENIC HISTORY 



The maps, Figs. 6.1 to 6.8, are fairly expressive of our present know- 

 ledge and postulates of the evolution of the western margin of the con- 





