ABSTRACTS AND DISCUSSIONS OF PAPERS 393 



Prof. Horace B. Patton : Wind is a transporting rather than abrading agent. 



Mr. E. E, Free : Salt crust in desert bolsons is a protection against erosion 

 bj^ wind. 



Prof. Erasmus Haworth : Caliche as protection against wind erosion has 

 not been given sufficient importance by geologists. (Cites coarse caliche con- 

 glomerates in western Kansas as "mortar beds." 



Mr. J. C. Jones : If erosion by wind is marked, evidence should be shown 

 in its deposition. Wind does transport, but how much? I am incliued to the 

 opinion that wind erodes but little. 



Prof. Erasmus Haworth : Wind transports sediment to streams and by them 

 is carried away. 



Mr. E. E. Free : Wind transports sediment back and forth, but does not 

 remove. (Cites oscillating sand-dunes in the Imperial Valley as instance.) 



SCULl'TUJiING OF ROCK BY WIND IN THE COLORADO PLATEAU PROVINCE 



BY HERBERT E. GREGORY 



Read in full from manuscript by Prof. C. F. Tolman, Jr. 



Session of Wednesday, August 4 



Tlie Society convened at 10.55 o'clock a. m.^, in the Geological Depart- 

 nimit of Stanford University, Dr. A. C. Lawson acting as Chairman and 

 J. A. Taff as Secretary. 



Seventy-nine meinbers and visitors were present. 



titles and ABSTRACTS OF PAPERS PRESENTED AND DISCUSSIONS THEREON 



SOME CHEMICAL FACTORS AFFECTING SECONDARY SULPHIDE OIIE 



ENRICHMENT 



BY S. W. YOUNG » 



{Abstract) 



An account of some laboratory experiments which have led to artificial 

 replacement by chalcocite. covellite, and chalcopyrite, and to tlie artificial 

 disintegration of boniite into calcocite, covellite, and chalcopyrite. all at or- 

 dinary temperature and under easily attainable conditions: also a discussion 

 of the probable chemical constitution of bornite and chalcopyrite, together with 

 some considoriitioiis on the role of the amorphous and colloidal sulphides and 

 of electro-clu'nii( al phenomena on secondary enrichment. (Experiments, arti- 

 ficial crystals, etcetera, forty-five minutes.) 



Presented in full extemporaneously. 



* Introduced by C. V. Tolmau, Jr. 



