CONTENTS Vll 



Page 

 Carboniferous salt and potash deposits of eastern Canada 



[abstract] ; by Albert O. Hayes 155 



Natural ^as decline curve [abstract] ; by Roswell H. Johnson 155 

 Quantitative method of estimating ground-water supplies ; by 



Oscar E. Meinzer 156 



Some results of deep drilling in the Appalachian oil and gas 



fields [abstract and discussion] ; by I. C. White 157 



Geology of the ore deposits of Kennecott, Alaska [abstract] ; 



by AxAN M. Bateman 157 



Conditions at Vesuvius in 1019 [title] ; by H. S. Washington 158 

 Sweet Grass Hills, Montana [abstract] ; by James F. Kemp 



and Paul Billingsley 158 



Cumberland Falls, Kentucky, meteorite [abstract] ; by Arthur 



M. Miller 159 



Cumberland Falls, Kentucky, meteorite [abstract] ; by George 



P. Merrill 160 



Phenol red indicator as an aid to the geologist [abstract] ; 



by Edgar T. Wherry 161 



The ternary system FesOg— SO., — HoO [abstract] ; by H. E. 



Merwin and E. Posn jak 161 



Bearing of experimental chemical data on the formation of 



smithsonite [abstract]; by Thomas L. Watson 161 



Contact-metamorphic deposit at the Mountain Lake Mine 



near Salt Lake City, Utah [abstract] ; by Austin F. Rogers 162 

 New and rare minerals formed in limestone by contact meta- 



morphism [abstract] ; by Arthur S. Eakle 162 



Register of the Boston meeting, 1919 163 



Officers, Correspondents, and Fellows of the Geological Society of 



America 165 



Proceedings of the Fifteenth Summer Meeting, held in conjunction with 

 the Sixteenth Annual Meeting of the Cordilleran Section, University of 

 California and Stanford University, August 3, 4 and 5, 1915 ; J. A. Taff, 



Secretary 177 



Session of Tuesday, August 3 178 



Epigene profiles of the desert [discussion] ; by Andrew C. Lawson 178 

 The bajadas of the Santa Catalina Mountains, Arizona [discus- 

 sion] ; by C. F. Tolman, Jr 178 



Origin of the Tufas of Lake Lahontan ; by J. C. Jones 179 



Some physiographic features of bolsons [title] ; by H. E. Gregory 179 

 Sculpturing of rock by winds in the Colorado Plateau Province 



[discussion] ; by H. E. (iREOORY 179 



Session of Wednesday, August 4 ISO 



Some chemical factors affecting secondary sulphide ore enrich- 

 ment [discussion] ; by S. W. Young 180 



Role of colloidal migration in ore deposits [discussion [ ; by John 



D. Clarke 180 



Some examples of progressive clianges in the mineral conijxjsition 

 of copper ores [discussion | ; by C. F. Tolman, Jk 180 



