178 PROCEEDINGS OF THE CORDILLERAN SECTION 



Page 

 Geologic age of the Coal Creek batholith and its bearing on some 

 other features of the geology of the Colorado Front Range [discus- 

 sion] ; by Hyrum Schneider 182 



Occurrence of flow-breccias in Colorado [discussion] ; by H. B. Patton. 182 

 Geology of a portion of the Santa Ynez River district, Santa Barbara 



County, California [title] ; by W. S. W. Kew 182 



Some interesting changes in the composition of the Salton Sea [title] ; 



by A. E. Vinson 182 



Examples of successive replacement of earlier sulphide minerals by 



later sulphides at Butte, Montana [title] ; by J. C. Ray 182 



Structure of the southern Sierra Nevada [discussion] ; by J. P. 



Buwalda 183 



Register of the California meeting 183 



Minutes of special meeting to canvass ballots for officers 184 



Session of Tuesday, August 3 



The first session was called to order at 10 a. m. Tuesday, August 3, in 

 Bacon Hall, University of California, by C. F. Tolman, Jr., chairman of 

 the Cordilleran Section, in the absence of President Arthur P. Coleman, 

 of the Geological Society. After announcements in regard to proposed 

 excursions, the dinner, and the official program, the following papers 

 were read in the order given : 



EPIGENE PROFILES OF THE DESERT 

 BY ANDREW C. LAWSON 



Kead in full from manuscript. 



Discussion 



In reply to a question by Professor Holway, Dr. Lawson explained that the 

 profile limit of the pan-fan stage in the desert profile was reached only occa- 

 sionally. Changes of climate usually interrupt the pan-fan stage. 



Prof. Bailey Willis cited instances in desert regions of China and Pata- 

 gonia to show that the pan-fan stage is rarely reached. 



Dr. Lawson is of the opinion that the Great Basin region is the ideal region 

 to illustrate instances cited. 



The paper is illustrated by four section diagrams and photographs of 

 examples in the region of Needless, San Bernardino County, California. 



THE BAJADAS OF THE SANTA CATALINA MOUNTAINS, ARIZONA 

 BY C. F. TOLMAN, JR. 



Presented in full extemporaneously. 



Discussed by Sidney Paige, who cites experiences in the same region. 



