May 4, 1921 smith: geological by-products 205 



to be credited to Dake. These are displacements on a large scale, 

 but observations of structural details have formed an essential part of 

 the general geologic descriptions by other geologists. A few petro- 

 graphic contributions have also resulted, such as the discovery of the 

 nepheline basalt on the Fort Hall Indian Reservation by Mansfield 

 and the detailed mapping of the Leucite Hills by Schultz. 



The close observation necessary in tracing coal outcrops and in 

 valuing public lands according to the thickness and character of the 

 coal beds has naturally led to intensive study of variation in sedi- 

 mentation. Thom's work on the Lance and Fort Union sediments, 

 in which the source of sediment deposited in flood-plain swamps is 

 traced by means of microscopic examination, and Hewett's discovery 

 of the persistent presence of bentonite in the Upper Cretaceous series, 

 proving volcanic activity in four States, are important contributions 

 to paleogeographic science — despite the bar sinister. 



The observed influence of the oil and gas studies by the Federal 

 geologists has aroused a larger interest in geophysics and in physical 

 chemistry, an influence which shows itself for the most part only in- 

 directly but is none the less of large profit to our science. Here again 

 close attention to structural details is yielding theoretical contribu- 

 tions, but probably the most noteworthy by-product of the oil and gas 

 work of the United States Geological Survey has been the augmented 

 interest in the petrology of sedimentary rocks. For purposes of 

 correlation and of interpretation of the details of "oil sand" stra- 

 tigraphy, petrographic methods must be developed and used. Ques- 

 tions of oil genesis, accumulation, and recovery lead to theoretical 

 problems whose solution will deepen our insight into earth processes. 



The study of mineral resources stimulated by the war also yielded 

 scientific profits, both subjective and objective. Foremost among 

 these I would place the appreciation of the physiographic relation of 

 manganese oxide deposits to stages of planation and of the fact that 

 degree of rock decay depends more upon physiographic stage than upon 

 climate; and the fact that the tracing of deposits of manganese ore 

 in the Appalachian Valley region disclosed a planation stage that 

 had previously received little attention. 



The study of the literature of foreign mineral reserves as a part of 

 the American problem of raw material supply has also added to our 

 appreciation of exact statement in geologic reports. The critical 

 reader of scientific literature may even profit by the faults of others, 

 and our geologists who have made largest use of the reports on the 



