628 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



140" 



138° 



136" 



134 



MES0Z 0IC SE DIMENTS 

 |^s$^ PLAINS 



PALEOZ OIC SE DIMENTS 

 I | MOUNTAIN 



I I TERRANE 



PALEOZOIC SEDIMENTS 



69° fg|j 



MAINLY PAL. a MES. SEDS. 



ACIDIC INTRUSIVE ROCKS 



MILES 



68° 



Fig. 39.14. Mountains and structural trends of the 

 lower Mackenzie River region and northern Yukon. 

 Map kindly supplied by P. E. Kent and W. A. C. 

 Russell, British Petroleum, Ltd. Heavy lines surround 

 mountainous areas. Dave Lord Ridge extends east- 

 erly from Alaskan border at 67 N. Lat. Canyon 

 Ranges are northwest end of Mackenzie Range. 



The fault structures (of the Ogilvie Mountains, Dave Lord Ridge, and 

 northwestern Richardson Mountains) are of the same general type as those 

 that form the Rocky Mountains of western Alberta, but a preliminary examina- 

 tion indicates that the stratigraphic displacement caused by individual faults 

 is not as great as in the case of the Alberta Rockies. Faults in the Dave Lord 

 Ridge area are irregular in trend and displacement, and do not result in the 

 typical Canadian Rocky Mountain topography. 



The anticline that forms the southern Richardson Mountains is of a type 



similar to the Wyoming Rockies uplifts, such as the Righorn and Wind River 

 mountains. The Franklin Mountains structures appear to be of the same type, 

 but on a smaller scale. 



The intrusion of the Old Crow Range batholith may have been in part re- 

 sponsible for Tertiary or late Mesozoic movements that took place in the Rritish 

 Mountains, and may have affected to some extent other structural patterns in 

 the region. 



Uplift of the coastal area following the retreat of Pleistocene glaciers is 



