THE 



JOURNAL OF GEOLOGY 



JULY-AUGUST, igoj 



THE RELATION BETWEEN CERTAIN RIVER TER- 

 RACES AND THE GLACIAL SERIES IN NORTH- 

 WESTERN CALIFORNIA. 



INTRODUCTION. 



By a reconnaissance trip in February, 1903, the writer traced 

 a definite system of river terraces between the coast at Hum- 

 boldt Bay and the Summerville basin on the border of a high 

 mountain cluster which was extensively glaciated in the Pleisto- 

 cene period and still possesses three tiny glaciers. The 

 importance of connecting the terrace system with the glacial 

 series was recognized and the writer devoted some da3's to a 

 detailed study of the extremely rocky and brushy canyon, seven 

 miles in length, which separates the Summerville basin from 

 undoubted deposits of the last great glacial stage. The work 

 was greatly facilitated by the operations of the early placer 

 miners, who have beautifully exposed most of the remnants of 

 old channels. It is believed that this study was rewarded by 

 exceptional success, of the truth of which the reader may judge 

 by perusal of the following pages: 



I have now discriminated in this region six distinct channel 

 levels (including the present river bed) which, to facilitate 

 the discussion, I will classify by letters, beginning with the 

 highest. In my descriptions 1 distinguish constantly between 

 "terrace " and " channel." Ordinarily each terrace consists of 

 Vol. XI, No. 5. 431 



