CONTENTS Vll 



Page 

 Volcanology of the Hawaiian Islands [abstract] ; by Henry S. 



Washington 72 



Origin and composition of certain oil shales [abstract and 



discussion! ; by Reinhardt Thiessen 72 



Session of Thursday afternoon, December 30 74 



Discussion of Doctor Thiessen's paper continued 74 



Titles and abstracts of papers presented at the afternoon session 



and discussions thereon 74 



Demonstration- material in geology [abstract] ; by H. F. Cle- 



LAND 74 



Cryptovolcanic structure in Ohio of the type of the Steinheim 



Basin [abstract] ; by Walter H. Bucher 74 



Probable cause of the localization of the major geosynclines 



[abstract] ; by Walter H. Bucher 75 



Postglacial faulting about Mount Toby, Massachusetts [en- 

 tire, with discussion] ; by F. B. Loomis 75 



Significance of the relation of proboscidean remains to the 

 surface of Nebraskan gumbotil, near Osceola, Clarke County, 



Iowa [entire, with discussion] ; by George F. Kay 80 



Vote of thanks i 8.3 



Preliminary sketch of the history of the lower Missouri [en- 

 tire] ; by Frank C. Greene 83 



Post-Illinoisan drift in northern Illinois west of the mapped 



Wisconsin moraine [abstract] ; by Morris Leighton 86 



Origin and history of Lake Chelan [abstract] ; by J. J. 



Runner 87 



Ancient rock deformations and their present expressions in 



western Vermont [abstract]; by Clarence E. Gordon 88 



Method of measuring and plotting the shapes of pebbles [ab- 

 stract] ; by Chester K. Wentworth 89 



Field study of the shapes of river pebbles [abstract] ; by 



Chester K. Wentworth 89 



Regional structure in north-central Texas [abstract] ; by E. H. 



Sellards 90 



Paleogeography and correlation of the marine tertiary de- 

 posits of the west coast [abstract] ; by Bruce L. Clark. . . 90 

 Probability of Pennsylvanlan glaciation of the Arbuckle and 



Wichita Mountain regions [abstract] ; by Samuel Weidman 91 

 Devonian black shales of western New York [abstract] ; by 



George H. Ghadwick 91 



Register of the Chicago meeting, 1920 92 



Constitution and By-Laws 94 



Publication rules 101 



Officers, Correspondents, and Fellows of the Geological Society of 



America 105 



Proceedings of the Twelfth Annual Meeting of the Paleontological Society, 

 held at Chicago, Illinois, December 28-30, 1920 ; R. S. Bassler. Secretary 119 

 Session of Tuesday, December 28 121 



