GEOPHYSICAL LABORATORY. 



Arthur L. Day, Director. 



The present calendar year has been a most important one for the 

 Geophysical Laboratory and for the problems which it seeks to develop. 

 It has proved important first because in this year we have been able 

 to demonstrate for the first time that rock formation in which vola- 

 tile ingredients play a necessary and determinative part can be com- 

 pletely studied in the laboratory with as much precision as though all 

 the components were tangible solids or Uquids. When tiny globules 

 of water or carbon dioxide are found inclosed within mineral crystals 

 undisturbed since the time of their formation, we know that such 

 volatile matter was present and must have had an active share in the 

 formation process in nature; in fact, mass for mass it must have been 

 incomparably more active than the silicates. We know also that many 

 of the mineral groups could not have taken their present form without 

 the aid of substances of which only significant traces now remain. 

 But we have not hitherto been able to perform such an operation in 

 full quantitative detail up to and beyond the critical temperature and 

 pressure of the volatile component (water), nor have we been able to 

 infer from existing laboratory data just how such volatile ingredients 

 participate in sihcate reactions of this kind at high temperatures and 

 appropriate pressures. The present work has therefore served to 

 advance our problem very materially and to develop its possibilities in 

 a way to justify the fullest confidence in its future. 



I shall reveal no state secret to-day in sajdng that there was once a 

 time when our confidence in the capacity of physics and chemistry to 

 solve these geological problems was not shared by all geologists. There 

 were some who were inclined to view with considerable apprehension 

 the vast ramifications and comphcations of natural rock formation as 

 a problem impossible of adequate solution in the laboratory. It is 

 therefore a matter of satisfaction to all those who have participated in 

 these efforts to see the evidences of this apprehension disappearing 

 gradually as the work has progressed. A careful appraisement of the 

 situation to-day, after ten years of activity, reveals the fact that the 

 tangible grounds for anxiety about the accessibility of the problems 

 which we then confronted are now for the most part dissipated. It 

 has been adequately demonstrated that the temperature conditions 

 which prevailed during the formative period upon the surface of the 

 earth are well within reach of known methods of accurate measure- 

 ment ; that the effects of pressure as a factor in the formation process 

 are insignificant compared with those of temperature, except where 

 volatile ingredients are concerned ; that the established generalizations 



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