122 A. HAGUE — THERMAL WATERS IN YELLOWSTONE PARK 



sedimentary rocks tested by that eminent authority, R. J. Strutt, of 

 England. It is noteworthy that the latter rocks referred to were speci- 

 mens of the oolite formation from near the celebrated springs of Bath. 



Strutt has also pointed out that siliceous igneous rocks are more radio- 

 active than basic lavas/^ a highly significant observation when it is 

 borne in mind that the rhyolite of the Yellowstone National Park stands 

 preeminent as an acid, crystalline rock. Iddings and Cross^^ have shown 

 that allanite in microscopic crystals is widely but sparsely distributed in 

 the siliceous igneous rocks of the Rocky Mountains, and has been detected 

 in the rhyolite of Yellowstone National Park. Now allanite is known to 

 carry small quantities of thorium. It is a coincidence worthy of note 

 that thorium emanation was determined in several of the hot pools, it 

 being first observed in this country in thermal waters in an obscure hot 

 spring in Norris Basin. I see no reason, however, to doubt the conclu- 

 sions of Messrs. Schlundt and Moore that the heat produced by radio- 

 active emanation from the rocks and waters is wholly inadequate to meet 

 the requirements. It seems necessary, at least from our present knowl- 

 edge, to look elsewhere for the source of the heat dissipated by the thermal 

 waters of the Yellowstone Park. 



Summary 



In conclusion I may state that I have attempted to show: (1) that 

 igneous activity was continued throughout Tertiary time; (2) that this 

 activity came to an end with the close of Pliocene time; (3) that during 

 the Eocene and Miocene deep-seated waters were active geological agents, 

 and that these waters were essentially primitive in their origin; (4) that 

 in strong contrast to the explosive, volcanic conditions of the Miocene, 

 the Pliocene lavas were emitted under far quieter conditions and built 

 up the successive flows that formed the rhyolite plateau; (5) that dur- 

 ing the many thousand years since the withdrawal of glacial ice the Plio- 

 cene rhyolites have, since the beginning of Pleistocene time, been steadily 

 undergoing progressive changes, brought about by the action of enormous 

 volumes of superheated vadose waters; (6) that the gases contained in 

 the thermal waters were in great measure derived from vadose sources: 

 (7) that the eruptions and periodicity of geysers are phenomena due 

 essentially to varying conditions of reservoirs and channels of super- 

 heated waters situated only short distances below the surface; (8) that 

 the phenomena as seen today represent a phase in the evolution of thermal 

 springs. 



1* R. J. Strutt : On the distribution of radium in the earth's crust and on the earth's 

 Internal heat. Proceedings of the Royal Society, ser. A, vol. LXXVII, 1906, p. 479. 



" Jos. P. Iddings and Whitman Cross : American Journal of Science, 3d ser., vol. 80, 

 August, 1885, p. 108. 



