THE PROBLEMS OF GEOLOGY.^ 



The subject "The Problems of Geology" was assigned to me. I 

 should not have ventured to select so formidable a topic for a brief 

 address. 



RELATIONS OF THE SCIENCES. 



We are all aware that geology is a many-sided subject. While 

 at the outset it was a simple observational study, it soon developed 

 physical, chemical, astronomical, and biological sides. The impor- 

 tance of these different sides has continuously increased, so that we 

 now often speak of physical geology, chemical geology, astronomical 

 geology, and biological geology. 



To appreciate the position of geology among the sciences it is 

 necessary to go back to fundamental definitions. Natural philosophy 

 in the old and broad sense may be defined as the science which treats 

 of energy and matter. But investigations have shown that the ether 

 also must be considered, and hence this definition needs modification. 

 Some physicists have been inclined to extend the scope of the term 

 ^'matter" to include matter in the old sense and also ether. But 

 it seems to me that until the two, which appear to be so different, 

 are shown to be essentially one, it is better to use the term "matter" 

 strictly in its old sense. But it is advisable to have a term which 

 shall include both matter and ether, and for this place the word 

 "substance" seems suitable.^ Using the term in this sense, natural 

 philosophy may be defined as the science which treats of energy and 

 substance. 



Physics is the science which treats primarily of energy; chemistry 

 is the science which treats primarily of matter. Thus physics con- 

 siders mainly the actions and transformations of energy through 



1 The principal address given in the Department of Geology of the International 

 ■Congress of Arts and Science at St. Louis, 1904. 



2 This definition of the word "substance" is different from that of Holman, who, 

 as I understand it, makes the term so comprehensive as to include matter, ether, and 

 energy. By him the word "matter" is apparently used to comprise what is here 

 ■covered by both matter and ether. — Silas W. Holman, Matter, Energy, Force and 

 Work, pp. 135 ff. 



