ABSTRACTS OF PAPERS 71 



have progressed, more and more details have been worked out, and during the 

 past season the work at the eastern margin of the range led to certain con- 

 clusions as to the relationship of the physiographic history of the mountain 

 range to that of the San Luis Valley. An excursion was made southward into 

 New Mexico for correlation purposes, and a more extended excursion was 

 made to the southwest over the Colorado Plateau to correlate the great physio- 

 graphic surfaces within the mountain areas with those of that famous plateau. 



Presented without notes, with the aid of diagrams. 



TERTIARY HISTORY OF THE LOWER SNAKE RIVER VALLEY, SOUTHWESTERN 



IDAHO 



BY JOHN P. BUWALDA 



{Al)stract) 



Mammalian remains recently collected in southwestern Idaho indicate that 

 the Payette formation is not Eocene (?), but Middle or Upper Miocene, that a 

 younger formation of Pliocene age is also present, and that the Idaho forma- 

 tion is Pleistocene instead of Pliocene. The rhyolite flows are mainly, if not 

 entirely, late Miocene or Lower Pliocene, and the eldest basalts are Middle or 

 Upper Miocene and no doubt represent part of the Columbia River lava series. 

 Pleistocene basalts also occur. The results tend to indicate that the Idaho 

 erosion surface is Neocene, possibly Pliocene, in age, instead of Eocene. 



Presented by title in the absence of the author. 



PHYSIOGRAPHIC DIAGRAM OF THE UNITED STATES 

 BY ARMIN KOHL LOBECK 



{Abstract) 



Unlike the usual block diagram, this one avoids distortion due to perspective. 

 A base map of the United States on a scale of 1 : 2,500,000 has been used. The 

 original drawing is thus about 76 x 48 inches in size and is to be reduced about 

 one-sixth for publication, giving a final scale of 1 : 3,000,000. The topographic 

 features of the country are to a certain extent exaggerated and idealized with 

 the purpose of suggesting the underground structure and its relation to the 

 topography. 



The map is intended for use in teaching regional physiography and geology 

 of the United States and as a base for laboratory exercises with classes. 



It has been prepared with the additional puri^ose in mind of using it as a 

 base for the plotting of the statistics soon to appear in the new Census reports. 

 Owing to the fact that it is not distorted and that it is based on a map of the 

 country showing county boundaries, it will be possible to prepare an outline 

 county map to assist in plotting data relating to population, agriculture, rail- 

 roads, industries, forests, mining, and irrigation, as these data are given by 

 counties in the Census reports. Thus the diagram can be used to work out 

 geographic and physiographic control as it has been exerted on human affairs. 

 Hence it will be of value not only to the physiographer and geologist, but to 

 the geographer as well. 



Presented without manuscript, with maps. 



