688 REVIEWS 



They are probably equivalent to the Nenana gravels on the north side 

 of the Alaska Range. 



Pleistocene and recent glaciation are described. The present snow 

 fields and glaciers are confined to the heads of the valleys and the higher 

 portions of the Alaska Range. 



Placer gold was first discovered in the Yentna district in 1905. 

 The total production up to 191 1 was $383,000. The gold is believed 

 to have been derived from quartz veins and stringers associated with 

 the intrusions in the slate and graywacke series. 



The coal, in beds ranging from 3 to 1 2 feet in thickness, is a medium- 

 to low-grade lignite. 



H. R. B. 



