BULLETIN OF THE CEOLOCICAL SOCIETY OF AMERICA 



Vol. 23, pp. 563-570, PLS. 34-36 NOVEMBER 9, 1912 



GLACIATION IN NOETPIWESTEEN ALASKA 



BY PHILIP S. SMITH^ 



(Read before the Society December 28, 1911) 



CONTENTS 



Page 

 Introduction 5G3 



Koyiikiik-Kobuk region 563 



Alatna river 560 



Noatak basin 567 



Introduction 



The observations here recorded were made in the course of geologic 

 investigations dealing primarily with the mineral resources of Alaska 

 and were, therefore, incidental rather than the main objects of research. 

 For this reason, as well as from the fact that the phenomena are highly 

 complex, the present paper aims at little more than the presentation of 

 some of the scattered observations that indicate the types of features 

 recognized, leaving the coordination and the detailed working out of the 

 Pleistocene-Recent history to the future. 



KOYUKUK-KOBUK REGION 



In the Koyukuk-Kobuk region shown in figure 1 the center of ice 

 occupation in the past was the highlands to the north of the Kobuk, 

 but the Zane Hills near the Koyukuk show evidences of past glaciation 

 in the form of the valleys and in small moraines similar to that of 

 figure 1, plate 34, which has a steep ice contact slope on the south or 

 up-valley side. Too little is known of the real heart of the range north 

 of the Kobuk to allow a full statement of its character, put it is prob- 

 able that in the Kobuk drainage there are at present no large glaciers. 

 In the past, however, glaciation of the valley type was pronounced, and 

 has markedly modified the topography and left deposits characteristic 



^ Manuscript received bj' the Secretary of the Society March 5, 1912. 

 Published by permission of the Director of the U. S. Geological Survey. 



(563) 



