682 W. M. DAVIS 



that physical or dynamical geology is the heading under which erosion, 

 volcanoes, and earthquakes are usually treated, as if the present 

 phenomena of the earth's crustal envelope were to be set aside from 

 the present phenomena of the hydrosphere and atmosphere, and 

 associated chiefly with the history of the past. But we have now cer- 

 tainly reached a point when the unity of all these subjects, their inter- 

 action in space, and their continuity through time demand their 

 association in a single group of studies which shall embrace all the 

 activities of the earth in their present manifestation; with the full 

 understanding that the present is only the latest addition to the past, 

 and that the past is only the integration of a vast series of ancient 

 presents. 



All these present physical activities, even if carried down to such 

 specialties as potamology and kumatology, are so closely associated 

 with the standard subjects of geography that it is difficult and unad- 

 visable to cut them asunder. Yet every one of them may be carried 

 to such a degree of detail as to stand apart, and gain rank as an inde- 

 pendent study. The accuracy of the geodesist, the minuteness of the 

 mineralogist, the high flights of the meteorologist have now gone so 

 far in their special development as to lead far away from each other, 

 when they are studied for themselves, however closely their more gen- 

 eral results may be associated. 



When, however, we study the inorganic features of the earth, not 

 as independent phenomena, but as elements of organic environment, 

 they all belong strictly in physical geography, or physiography. 

 Parenthetically, let me say that I regret the excessive breadth given 

 to this term by British students, and the narrowness imposed upon 

 it by those Americans who would limit it to the study of the lands. 

 When we pursue the subdivisions of physiography, nomenclature 

 becomes incomplete: climatology is unique in being a name for the 

 study of the atmosphere in so far as it determines organic environ- 

 ment; economic geology is a study of useful minerals and rocks, but 

 is less strictly treated as an objective subdivision of physiography than 

 is climatology; and there is associated with it so much of ingenious 

 artifice in the exploitation and treatment of mineral products that we 

 are apt to put the cart before the horse and think that we make gold 

 or coal serve our needs, instead of realizing that we make ingenious 



