614 PHYSIOGRAPHY 



inclined to explain the surface features as the result of exogene 

 processes because he is solely concerned with the survey of the 

 surface. 



The divergence of these two views is due to the fact that the rela- 

 tion between internal structure and superficial form is most compli- 

 cated. There are not a few localities where the latter is most closely 

 dependent upon the former; but there are also very many places 

 where such a relation is unfortunately absent. The highest mountain 

 range of the earth, the Himalaya, consists of strata which have been 

 most tremendously compressed, yet in Belgium we find regions of 

 scarcely less complicated structure which present an almost plane 

 surface. In the Alps may be found regions of the most complicated 

 structure lying close beside others of the very simplest, yet the latter 

 do not appear to be on that account less mountainous in character. 

 In illustration one needs only to recall the south Tyrolean Dolomites 

 and compare them with the Glarner Alps. The picture of the face 

 of the earth drawn by Edward Suess is widely at variance with 

 that presented by a geographical map. The morphologic point of 

 view of the physiographer does not coincide with the tectonic one of the 

 geologist. It would be a mistake to attempt to subordinate the one 

 to the other. One must accustom himself to recognize the fact that 

 he is here dealing with different conceptions of equal rank, and that 

 one should not and cannot supplant the other, but rather must be 

 mutually enriching. The way in which this mutual enrichment is to 

 come about has been especially developed in the United States. Here 

 topography and geology are not so hostile to one another as in most 

 European countries. They are not in the hands of different Govern- 

 ment Bureaus, but are both fostered in one and the same institution, 

 the Geological Survey. And if the activity of the topographer is 

 separated from that of the geologist, yet a lively intercourse exists 

 between both as result of the association in work. In the arid regions 

 of the far West, where the mountain structure is not hidden by dense 

 vegetation, the map-maker may easily recognize the relation of the 

 topographic surface to the stratigraphic structure, and the geologist 

 sharpens his perception of the forms of the earth's surface, since he 

 must often do some topographic mapping. Geomorphology owes its 

 more recent advances, in no small degree, to the far West. G. K. 

 Gilbert, as result of his work there, has established a series of funda- 

 mental principles upon which others, especially W. M. Davis, have 

 based further advances. The greatest service performed by Davis 

 consists in the systematization of the complicated relation between 

 the internal structure and the surface forms whose causes had already 

 been explained in large part. Those portions of the earth's surface 

 where a direct dependence of the surface forms upon the structure is 

 recognizable, are young, and those where such a dependence is entirely 



