BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 



Vol. 19, pp. 255-314, FLS. 18-19 OCTOBER 28, 1908 



PALEOZOIC AND ASSOCIATED EOCKS OF THE UPPEE 



YUKON", ALASKA^ 



BY ALFRED II. BROOKS AND E. M. KINDLE 



(Presented by title before the Society December 31, 1907) 



CONTENTS 



Page 



Geography 255 



Geologic investigations 250 



Geology 261 



Introduction 261 



Pre-Ordovician 264 



Ordovician 271 



Silurian 272 



Devonian 277 



Carboniferous 291 



Mesozoic 304 



Tertiary 307 



Quaternary 309 



Structure 310 



Outline of geologic history 311 



Geography 



The province here to be considered embraces that part of the Alaska- 

 Yukon basin lying adjacent to the International boundary (141st merid- 

 ian) and stretching westward to the 152d meridian. The Tanana river 

 can be regarded as its southern boundary, and it extends northward to 

 about the 67th parallel of latitude. Most of the observations on which 

 the present paper is based were made in the eastern half of this area. 



This region is drained by the Yukon river and its tributaries, the larg- 

 est being the Porcupine river, joining the Yukon from the northeast at 

 its great bend near the Arctic circle, and the Tanana, flowing westerly, 

 which joins the Yukon about 200 miles to the southwest of the mouth of 

 the Porcupine (see map, figure 1). The region forms a part of the so- 



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

 Manuscript received by the Secretary of the Society April 7, 1908, 



XXVI— BuLU Geol. Soc. Am., Vol. 19, 1907 (255) 



