PALEOZOIC ROCKS, STUVER SERIES. 61 



Where best exposed between the two limestone areas of the Lisburne formation 

 to the north of the Anaktuvuk, the Stuver series, forming the lower part of the 

 longer limb of an anticline, dips southward at an angle of 30° and passes beneath the 

 limestone of the Lisburne formation. The relation of the two formations imme- 

 diately at the contact is concealed by talus, but near by begins an exposure which, 

 extending for several miles along the front of the mountains, shows the Lisburne 

 formation dipping southward at an angle of 20°, this dip being but 10° less than 

 that of the Stuver series, which, as it nears the Lisburne formation, gradually 

 decreases southward. From this it is inferred that the Lisburne, where not faulted, 

 probably rests conformably on the Stuver series. If any unconformity exists, it 

 must be very slight. 



As shown on the geologic map (PI. Ill), the exposure of the Stuver series is 

 limited to a narrow belt, about 5 miles in width, that trends eastward for an unknown 

 distance from the Anaktuvuk Valley, lying between the eroded edges of the Lis- 

 burne formation. The series is also supposed to form the bed-rock floor of the 

 Anaktuvuk Valley, beneath the glacial drift, from the north edge of the mountains 

 for a distance of 10 to 12 miles southward, to near the southern edge of the Lisburne 

 formation. There are some small exposures of its upper member beneath the 

 Lisburne along the base of the mountains on both the east and the west side of the 

 valley, while on the south it has probably been brought into contact with the Lower 

 Carboniferous of the Fickett series by faulting. Both here and at the north edge of 

 the series the faulting seems to be normal. 



Structure. — To convey a clearer conception of the controlling conditions here, it 

 should be noted that the Stuver series lies in an east-west zone that exhibits the 

 most marked geologic disturbance of the region. Pronounced faulting extends 

 southward into the range for a distance of 15 to 20 miles from its seaward face. 

 This zone extends along the crest of the divide between the Yukon and Arctic coast 

 drainages, in the region at the head of John and Anaktuvuk rivers, and at the southern 

 part of the great crescent formed by the north front of the Endicott Range. The 

 beds in a general way retain the east- west trend noted in the older Skajit and 

 Totsen series. Roughly considered, the uplift, which, judging from sediments in the 

 post-Paleozoic rocks and the unconformable relations of these to the Paleozoic rocks, 

 seems to have been going on since middle or late Paleozoic time, apparently took 

 place in the form of a broad anticline, whose longer limb extends with gentle slope 

 southward and whose shorter limb forms in part the north front of the range. Eleva- 

 tion was accompanied by faulting. The thrust or movement came from the south 

 and apparently produced an overturned fold in the terranes forming the crest of the 

 anticline. The faulting which accompanied this movement broke the beds into 

 several great fault blocks. Erosion followed, which finally brought the Stuver 



