GEOPHYSICAL LABORATORY * 



Arthur L. Day, Director. 



Although the earlier reports of this Department have contained brief state- 

 ments of the purpose with which this work was undertaken, viz., to enter 

 upon a quantitative study of rock formation in the laboratory, which shall 

 include both the minerals and rocks which are geologically important and 

 those which are economically useful, those which are formed directly from 

 the magma and those which were formed by subsequent alteration, there are 

 some details of such an undertaking which are quite as important as an ex- 

 plicit statement of purpose. The individual problems contemplated by such 

 a plan are problems for physics and physical chemistry. Furthermore, a 

 number of these problems are in no sense new. It is therefore a matter of 

 at least equal interest to know why, if such problems have already been 

 recognized and some of them even widely discussed, they have not been 

 wholly or partly solved before. Are there questions of practicability in mak- 

 ing such an application of the measuring sciences to the mineral kingdom 

 which have operated to discourage such attempts in time past, and, if so, is 

 the outlook more favorable now ? 



One of the most important reasons for this delay in attacking these 

 obvious problems lies in the fact that the measured relations established 

 by the exact sciences have not been of adequate scope to meet the needs 

 of large geologic or petrologic questions. The great body of physical and 

 physico-chemical measurements have been confined, for example, to the re- 

 gion between o° and ioo°, while rock formation may have extended over a 

 temperature region reaching to 1500°, or perhaps even higher — an enormous 

 range over which to stretch the application of methods and one in which 

 the common forms of apparatus will not only fail, but the apparatus itself is 

 immediately threatened with destruction. 



It is, therefore, not altogether certain, at least not without additional physi- 

 cal and physico-chemical investigation, that the generalizations hitherto estab- 

 lished are directly applicable to problems of geophysical scope. There has 

 been a gradual recognition of the fact that although many of the problems 

 of geology and of petrology are directly physical in character, they are sepa- 

 rated by an unexplored region from most of the laboratory methods and 

 measurements undertaken in our laboratories. To bridge this gulf the physi- 

 cist has done but little, perhaps because of failure to appreciate the oppor- 

 tunity or need for it; and the petrologist has not been sufficiently familiar 

 with the tools in use by the exact sciences. 



* Situated in Washington, D. C. Grant No. 602. $51,020 for investigations and main- 

 tenance during 1910. (For previous reports see Year Books Nos. 3-8.) 



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