234 P. C. SCHRADER— GEOLOGICAL SECTION IN NORTHERN ALASKA 



Page 



Anaktoovnk series (Lower Cretaceous) 245 



Character and occurrence 245 



Structure 245 



Age 245 



Koyukuk series (Lower Cretaceous) 246 



Character and occurrence 246 



Structure 246 



Age ' 246 



Bergman series (Cretaceous ?) 246 



Character and occurrence 246 



Structure : 247 



Age 247 



Nanushuk series (Upper Cretaceous) 247 



Character and occurrence 247 



Age 248 



Upper Cretaceous on the Koyukuk ... 248 



Tertiary — Colville series 248 



Pleistocene 249 



The deposits 249 



Goobic sands 249 



Glacial material 250 



Ground ice, marsh, muck, mud flats, etcetera 251 



Geography and Topography 

 in general 



The section lies in the hitherto unexplored part of northern Alaska. 

 It extends from the 66th parallel north latitude roughly along the 152d 

 meridian by way of the Koyukuk, John, Anaktoovuk, and Colville rivers, 

 a distance of nearly 400 miles, to the Arctic coast.* 



Geographically the region traversed by the section comprises three 

 distinct provinces, that of the Koj^ukuk or southern, the mountain or 

 middle, and the Arctic slope or northern. 



KO Y UK UK PRO VINCE 



This province, extending from the 66th parallel more than 100 miles 

 northeastward to the southern base of the mountains, lies mainly in the 

 northwestern part of the large Koyukuk basin. f The province in gen- 



* For a fuller account of this region the reader is referred to the Preliminary Report on a Re- 

 connaissance in Northern Alaska along the 152d Meridian to the Arctic Coast, soon to be published 

 by the U. S. Geological Survey. 



fFor a more complete description of the Koyukuk basin the. reader is referred to "Preliminary 

 report on a reconnaissance along the Chandlar and Koyukuk rivers, in Alaska, in 1899." Twenty- 

 first Ann. Rep. U. S. Geol. Survey, part 2, p. 467. See also " Bulletin of the American Geographical 

 Society," vol. 34, No. 1, February, 1902 :. " Recent work of the U. S. Geological Survey in Alaska," 

 p. 1. 



