112 W. M. DAVIS RELATION OF GEOGRAPHY TO GEOLOGY 



vides material for many similar pages. In writing such articles the 

 geographer becomes for the time being and in a very limited way a geolo- 

 gist, for he is not trying to describe present forms, but to discover how 

 certain agencies have acted in past time. As long as such problems are in 

 discussion attention is naturally and properly more directed to past proc- 

 esses than to present results, and the investigation of past processes as 

 such is evidently a geological matter. It is onl}^ after problematic proc- 

 esses are satisfactorily settled that they can be safely employed in ex- 

 planatory descriptions of present forms ; onl}^ then can the geographer 

 return from his excursion on geological fields to his own science. Simi- 

 larly a chemist, who wishes to filter or to weigh a precipitate and who 

 finds no satisfactory methods of performing this purely physical process 

 described in the standard works on physics, must for a while stop being a 

 chemist and turn his attention to inventing a mechanical device for filter- 

 ing or weighing things, thus transforming himself for the time being and 

 to a limited extent into a physicist ; but the invention once made and put 

 to use as a means of finding out the composition of things, the investigator 

 becomes a chemist again. 



It is through considerations of this kind that one becomes convinced of 

 the necessity of explanatory treatment in modern geography. 



Part III. The Diminution of apparently geological Matter in 



GEOGRAPHICAL DESCRIPTIONS 

 THE ADVANTAGE OF TERMS OVER PHRASES 



In view of the demonstrations given in the foregoing pages, it should 

 be understood that the place of a description in a classification of the 

 sciences is determined by its object rather than by the means emplo3'ed in 

 reaching the object, and it should be recognized that explanatory geo- 

 graphical descriptions are of greater value than empirical descriptions; 

 and from these conclusions it further ensues that the description of the 

 Front Eange given at the outset is not geology but good geography. If 

 one grants the reasonable postulates with which the demonstrations begin 

 and follows the demonstrations through their logical course, the conclu- 

 sion just stated is inevitable; but do we not all know that many of us, 

 especially our opponents, are not inclined to grant reasonable postulates, 

 and that some opponents are unwilling to follow logical demonstrations? 

 Do we not furthermore all know the opinion of the man who is convinced 

 against his will? In view, then, of the difficulty of demonstrating to 

 geologists the essentially geographical character of an apparently geo- 

 logical description, let us adopt another method of reaching a common 



