BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 19, pp. 315-338 October 28, i908 



GEOLOGIC EECONNAISSAi^CE OP THE PORCUPINE 

 VALLEY, ALASKA" 



BY E. M. KINDLE 



{Presented by title before tlie Society December 31, 1907) 



CONTENTS 



I'age 

 Topography and drainage 315 



Structure 317 



Folds 317 



Faults 318 



Stratigraphj"^ and faunas 320 



Pre-Ordovician series 320 



Ordovician limestone 322 



Ordovician fauna 823 



Silurian dolomites 324 



Middle Silurian fauna 325 



Graptolite fauna 325 



Devonian limestone 327 



Devonian fauna 327 



Devonian shale aud igneous series 329 



Carboniferous shales and limestones 330 



Carboniferous faunas 332 



Extent of the Carboniferous in northern Alaslia 335 



Tertiary beds 336 



Lavas 337 



TOPOGEAPHY AND DRAINAGE 



Topographically the country traversed by the Porcupine river between 

 the International boundary and the Yukon falls into two distinct prov- 

 inces. The most easterly of these includes the low mountain and hill 

 country extending westward irom the boundary about 100 miles. The 

 Yukon flats comprise the westerly belt. 



A little more than 100 miles of the lower course of Porcupine river 

 lie in the extensive alluvial plain known as the Yukon flats. Along this 



(J Manuscript received by the Secretary of the Society July 4, 1908. 

 XXXI — Bull. Geol. Soc. Am., Vol. 10, 1"J07 



(315) 



