Apkil 14, 1911] 



SCIENCE 



565 



action may cease and the geyser, as such, 

 may become extinct. It is frequently 

 stated that some geyser has ceased to be 

 active and that this indicates the slow dis- 

 sipation of the original source of heat. 

 This I believe to be an error. The change 

 is simply due to a shifting of the channel 

 of the ascending waters. 



If, on the other hand, there should be 

 marked climatic changes and arid condi- 

 tions should set in over the park and ad- 

 joining mountains, in my opinion, thermal 

 springs would become extinct. Should 

 this happen it would be evident beyond all 

 question that the waters were derived 

 from vadose sources. Again, with the dis- 

 integration of lavas and the building up 

 and enlargement of reservoirs, existing 

 conditions of hydrostatic pressure would 

 cease and the circulating waters, unable to 

 rise, would distribute themselves laterally; 

 in which case there might break out at the 

 base of the rhyolite plateau calcic springs 

 such as we now find and have already de- 

 scribed. 



In all probability the magnitude of a 

 geyser is, in a measure, dependent upon 

 the size of the underground reservoir or 

 series of reservoirs, produced by the dis- 

 integration of lavas along channels of as- 

 cending waters. It has been demonstrated 

 by self-registering thermometers that cool 

 infiltrating waters may drain into partially 

 erupted reservoirs after geyser eruption. 

 This has been shown in the case of the 

 Giantess Geyser. The question was once 

 asked by an attendant at the hotel who 

 had spent several summers in the park, 

 why Old Faithful was more apt to be sev- 

 eral minutes behind time in September 

 than in July. I am not aware that such a 

 condition was ever established, but if so, 

 my reply would be that in the autumn the 

 infiltration of surface waters is not as 

 rapid as in early summer, hence a retard- 

 ing of the eruption by several minutes. 



It is probable that the Norris Geyser 

 Basin, in its thermal development, is later 

 than the Upper Geyser Basin. In the 

 former are found the early and more acid 

 conditions, the waters of the geysers are 

 mainly neutral and form deposits of arseni- 

 cal sulphides, alum, and ferric salts. These 

 phenomena are for the most part absent in 

 the Upper Geyser Basin, where the waters 

 have reached a more advanced stage and 

 possess a siliceous' alkaline composition. 



With the exception of arsenic and 

 boron, which occur in minute quantities, 

 all the elements brought to the surface in 

 solution by the thermal waters of the park 

 have been found in the rhyolite. In this 

 connection it may be said, and it is gener- 

 ally accepted by those who have studied 

 the region, that the mineral waters of 

 PfaefEers, in the Tyrol, have a vadose 

 origin, and analyses show that both these 

 elements are present.'' Both these elements 

 are found associated together in many ther- 

 mal waters of Europe. Not only is it true 

 that, with these exceptions, all the elements 

 are accounted for in the rocks, but the 

 proportion of the ingredients in the waters 

 bears a remarkable relation to that of the 

 elements in the rhyolite itself. Silica and 

 the alkalies are the predominating ele- 

 ments. Even lithia, which is a feature of 

 many siliceous lavas, has been quantita- 

 tively estimated in all these thermal waters. 

 The water from Old Faithful yielded 

 .0056 of a gram per kilogram of water, 

 which, according to the theoretical com- 

 position, shows that lithium chloride forms 

 2.44 per cent, of the amount of material 

 held in solution. The neighboring Giantess 

 Geyser carried precisely the same amount 

 of lithium chloride. The low percentage of 

 iron, manganese, lime, and magnesia con- 

 tained in the ascending waters is readily 

 accounted for by the comparatively small 



' M. De Launay, Annales des Mines, February, 

 1894. 



