DRAINAGE FEATURES OF CALIFORNIA 495 



After considerable discussion of both papers, the Section adjourned at 

 12.30 p m, to meet at Berkeley in the afternoon. 



At 2.30 p m the Section met in the rooms of the Geological Depart- 

 ment of the University of California and proceeded with the reading of 

 the papers on the program. 



The following papers were then read and discussed : 



DRAINAGE FEATURES OF CALIFORNIA 

 BY ANDREW C. LAWSON 



A comparative study of the geomorphy of the Sierra Nevada and the Coast ranges. 

 There is a remarkable contrast in the character of the river valleys in the two 

 mountain systems, those of the Sierra Nevada being consequent and the geomorphy 

 immature, while those of the Coast ranges are subsequent and the geomorphy ma- 

 ture. In the Coast ranges the geomorphic profiles of the river valleys, leaving out 

 of consideration the head- water streams, are not so steep as in the Sierra Nevada, 

 and the valleys are much wider as a general rule. The divides are rounded or 

 ridge-like, with but small remnants of the earlier geomorphic cycle identifiable, 

 in the Coast ranges, while in a large part of the Sierra Nevada the divides have a 

 marked table or plateau form. The drainage of the Coast ranges is clearly con- 

 trolled by the structure of the country, while the streams of the Sierra Nevada cut 

 across the strike of the rocks and have made but little lieadway in the working out 

 of canyons along the strike of the softer formations. 



The Klamath river is regarded by the author as partly having the consequent 

 character of the Sierra Nevada drainage and partly the character of the Coast Range 

 drainage. The Trinity river and its prolongation in the lower Klamath belongs 

 to the Coast Range system, being parallel to the strike of the country and in part 

 mature in its development, while the upper Klamath is consequent and young. 

 This afi'ords us a basis for the separation of the Klamath mountains from the Coast 

 ranges, angl supports the orogenic correlation of the Klamath mountains with the 

 Sierra Nevada. The comparison thus made points clearly to the conclusion that 

 the Sierra Nevada and probably also the Klamath mountains are of later date than 

 the emergence of the Coast ranges which inaugurated the present cycle of geo- 

 morphic evolution. But the subsequent valleys of the Coast ranges are in several 

 instances known to have been evolved after the deformation of the Pliocene, and 

 we are thus forced to place a very late geological date upon the tilting of the Sierra 

 Nevada orographic block. 



DESCRIPTION OF BA TES HOLE, WYOMING * 

 BY WILBUR C. KNIGHT 



\_Ahstract] 



Bates hole, a great natural depression, is located along the east and west bound- 

 ary line between Carbon and Natrona counties, Wyoming, extending southward 



* Illustrated with lantern slides. 



