8i6 POPULAR SCIENCE MONTHLY. 



might nearly as well be buried. The geologist who seeks, for ex- 

 ample, the causes of volcanism, will find help in his study of the 

 distribution and relative action of existing volcanoes in other 

 words, he can not keep from geography. The geographer, in his 

 turn, needs the perspective of ancient volcanic history, if he would 

 appreciate his own facts. Because he has commonly had no such 

 vista, he has burdened generations of boys with the solemn 

 blunder that a volcano is a burning mountain. Thus we may 

 vindicate for each science its own center while granting a generous 

 measure of common facts. The difference is in the point of view, 

 the aim, and method of treatment ; the geologist seeks largely that 

 which has been, the geographer that which is, and each must be 

 known in the light of the other. It is precisely the case with two 

 biologists, one of whom studies living, the other fossil, forms. 

 The day is past when they can work apart ; yet none would deny 

 that their fields are reasonably differentiated. 



The new geography is a recent growth. Its facts and principles 

 are little diffused and have not found their way into text-books. 

 Thus it came about that the Conference report on geography is 

 characterized as the most revolutionary of all those received by 

 the Committee of Ten on secondary-school studies. Even scientific 

 surveys of the several States do not yet show much impress of the 

 new doctrines. Prof. Davis, the geographer of Harvard Univer- 

 sity, affirms that his students search, with meager reward, for ac- 

 counts of physical features in the literature of the several States. 

 As the same writer has truthfully said, systematic study of 

 topography is largely American, and for the reason that the 

 broad object lessons of the Appalachians and of the West gave 

 our scholars the opportunity and the stimulus to lead in such 

 researches. 



The central principle of the new geography established by 

 Powell, Button, Gilbert, Davis, and other American geographers 

 and geologists is the doctrine of a base level of erosion as the 

 goal of the destructive processes. Given an early "construc- 

 tional " land surface, such as a newly raised sea bottom, and it will 

 pass through what is called a cycle of development. Youth, with 

 extended uplands and steep, narrow valleys, is followed by a much 

 dissected, highly diversified topography marking the stage of 

 maturity, whence is a gradual passage to the low reliefs, slight 

 gradients, and quiet monotony of old age. During this cycle all 

 forms of scenery have place, and in untrammeled variety, depend- 

 ent upon climate and the constitution and structure of the mass 

 upon which this land sculpture is wrought. Thus the horizontal 

 beds of the Catskills give one type, the folded sediments of the 

 Appalachians another, and the crystalline masses of the Adiron- 

 dacks a third. Before such a cycle is completed in an actual base 



