498 SCIENCES OF THE EARTH 



the present, and the future also, as fast as it arrives. There is no pos- 

 sibility, in the understanding that we have now gained of earth-sci- 

 en'ce, of stopping the geological record at any stage of the pleistocene, 

 and calling the rest geography: that would involve the resurrection 

 of buried theories, which held the past to be unlike the present order 

 of things. 



Conversely, geography is stultified when absolutely limited to the 

 things of to-day, as if the things of the past were of another nature. 

 It is of course popularly so considered, and perhaps for that reason 

 its scientific development is stunted. When regarded objectively, the 

 geography of to-day is nothing more nor less than a thin section at the 

 top of geology, cut across the grain of time; and all other thin sections 

 are so much more like the geography of to-day than they are like 

 anything else, that to call them by another name except perhaps 

 paleogeography would be adding confusion to the earth's past 

 history instead of bringing order out of it. Our plain duty is to 

 emphasize the continuity of events, that great result of our studies, 

 and not to imply a break in their succession by using unlike terms for 

 different members of a single series. 



Geology thus being composed of a succession of countless geo- 

 graphies, geography, in its widest sense, is likewise composite, in- 

 cluding its inorganic and its organic parts. It is particularly con- 

 cerned with the surface of the earth to-day, as the home of life; but 

 surface and to-day must here be very freely construed ; for we must 

 draw upon the sub- and supersurface parts, and on the days before 

 to-day, whenever we find profit in so doing. When we study the 

 shape and size of the earth, we touch upon what may be developed 

 into geodesy. When we study the inorganic parts of the earth for 

 themselves, in what may be called their static relations, we enter 

 upon mineralogy and petrology, or geochemistry; for it must be 

 remembered that water is a mineral and that air is a rock. When 

 we study the dynamic relations of the inorganic parts of the earth, 

 we have geophysics, within which oceanography and meteorology are 

 subdivisions, of rank similar to terrestrial magnetism and to that 

 large category of phenomena that includes the activities of the 

 earth's crust. It is true 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 phenomena of the hydrosphere and 

 atmosphere, and associated chiefly with the history of the past. But 

 we have now certainly reached a point when the unity of all these 

 subjects, their interaction 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 mani- 

 festation; with the full understanding that the present is only the 



