REPORT OF PHOTOGRAPH COMMITTEE 527 



The report of the Photograph Committee was adopted and the usual 

 appropriation of $15 was voted. 



The Auditing Committee reported that the accounts of the Treasurer 

 had been found correct, and the Society adopted the report. 



The Council submitted its report on the matter of the proper pronun- 

 ciation of the name " Cordilleran, 1 ' which had been referred to the 

 Council at the Washington meeting, 1899. It was recommended that 

 the name be pronounced " Cor-dil-ye-ran." The report was adopted. 



The first paper of the scientific program was 



GEOLOGY OF SNAKE RIVER PLAINS, IDAHO 

 BY ISRAEL C. RUSSELL 



[Abstract] 



Suggestions in reference to the origin of the Snake River basin. Tertiary lakes. 

 Extent and thickness of the Snake River lava and its relation to the Columbia 

 River lava. Lack of evidence of fissure eruptions. Presence of numerous extinct 

 volcanoes, both on the plains and among the neighboring mountains, which dis- 

 charged great quantities of highly liquid lava. Distinction between cinder cones 

 and " lava cones." The extensive lava flows from the Cinder buttes, which illus- 

 trate the mode of origin of the older members of the series of lava sheets to which 

 they belong. Corrugated surfaces of recent lava streams passing into hollow pressure 

 ridges. Origin of the characteristic ridges on the surfaces of the older lava sheets. 

 Characteristics of lava flows which entered water bodies. Lava caves formed by 

 the arching of a viscous crust on a lava stream, due to lateral pressure; to outflow 

 of liquid lava from beneath a rigid crust ; and to the blowing out of plastic lava by 

 steam during the formation of parasitic cones. Evidence that "aa" surfaces are 

 due to the breaking of a brittle crust on a lava stream on account of an underflow 

 of still plastic lava. The canyon of Snake river; influence of lava sheets on its 

 topography. Great springs on the northern side of Snake River canyon below 

 Shoshone falls. The classification of springs. The term "canyon spring" defined. 

 Remarkable spring-formed alcoves or small side canyons in the northern wall of 

 Snake River canyon. 



The paper was discussed by B. K. Emerson and J. E. Wolff. An 

 abstract is printed in Science, volume xv, January 17, 1902, pages 85-86, 

 the report of which the paper presented is a partial abstract, forms Bul- 

 letin no. 199 of the U. S. Geological Survey. 



The two following papers were presented together and discussed as 

 one, the second paper being a series of lantern illustrations : 



STRATIGRAPHY AND STRUCTURE LEWIS AND LIVINGSTONE RANGES, MONTANA 



BY BAILEY WILLIS 



This paper is printed as pages 305-352 of this volume. 



