ABSTRACTS OF PAPERS 61 



Discussion 



Dr. A. W. Gkabau: The last illustration shown resembles veiy closely the 

 Nagelfluh of Salzburg — a fluvio-glacial deposit of late IMeistocene origin — and 

 Doctor Clarke's comparison of these Devonic deposits with the Nagelfluh 

 seems a very happy one. I would ask Doctor Clarke if indications of chatter 

 marks, such as are common on the pebbles of the Old Red, are found in the 

 pebbles of the Scaumenac region. 



Doctor Clarke replied that he did nut think chatter marks were evident on 

 these blocks. 



The Society adjourned al)Out 12.20 o'clock and reconvened in sections 

 at 2.30 o'clock. 



TITLES AND ABSTRACTS OF PAPERS PRESENTED BEFORE THE FIRST SECTION 



AND DISCUSSIONS THEREON 



The first section met, with Vice-President Horace B. Patton as pre- 

 siding officer and E. 0. Hovey as Secretary, and took up the papers 

 entered in the printed program under Group A: Dynamic, Structural, 

 Glacial, Physiographic. 



ORIGIN OF THE FED BEDS OF WESTERN WYOMING 

 BY E. B. BRANSON 



{Abst7~act) 



The Red Beds of western Wyoming are about 1,400 feet in thickness along 

 the western outcrops and thin eastward. Eight hundred and ninety feet from 

 the bottom they contain a formation, 40 to 60 feet thick, which is plainly of 

 subaerial origin. Some 200 feet above this a highly cross-bedded sandstone 

 about 60 feet thick seems to have originated from wind-blown materials. Near 

 the top are extensive beds of gypsum up to 40 or .50 feet in thickness. All of 

 the Red Beds in western Wyoming, excepting the subaerial formations above 

 mentioned, seem to have been marine in origin, the evidence being : wide-spread 

 deposition of gypsum, beds of sandstone of uniform thickness composed of 

 uniform materials extending over wide areas, and with wide-spread ripple- 

 markings on horizontal surfaces. The gypsum can not be a deposit from fresh 

 water in inland basins, because no other carbonates are deposited or occur with 

 the gypsum, because of the rarity of sedimentary impurities, because of the 

 absence of sodium ehlorid(! and other salts, because of the excessive time re- 

 quired for deposition. There are no evidences of erosion of the near-lying 

 rocks during the time when the gypsum was being deposited. 



I»ead in I'lill frdiii iiiaiiiiscript. 



Discussion 



I'rof. A. W. Grahau : I would question the interpretation ()f any i)art of the 

 Kcd I'.cds us of marine origin. The absence of positive indications of subaerial 



