196 REPORTS ON INVESTIGATIONS AND PROJECTS. 



impressions of European mountains may not unjustly be qualified 

 as leaning on physiography ; for a just balance they need to be 

 supported equally in geology ; but as the results of purely geologic 

 investigation have been gathered in detail and elaborately discussed, 

 the presentation of physiographic facts is a step toward establishing 

 a general equilibrium, and this is the more important since the 

 current interpretations result in different conclusions. 



Geologic research, reaching only the facts of stratigraphy and 

 internal structure, led to the commonly accepted view that mountains, 

 considered as elevations above sea, owe their position to those forces 

 which produced the folds or dislocations observed in the rocks. 

 Physiographic research has, in some instances, established the lapse 

 of an interval of time often equivalent to geologic ages between the 

 development of the structure and the growth of the height above sea- 

 level. Mountain growth is thus recognized as a phenomenon dis- 

 tinct from and often more recent than mountain structure. This is 

 now known to be true of those ranges of North America and Asia 

 which have been made the objects of physiographic study ; it is not 

 generally held to be true of the ranges of Europe which have been 

 investigated chiefly geologically. 



The object of my reconnaissance was to ascertain to what extent 

 the physiographic methods employed in America and Asia might be 

 applied in Europe and what likeness or difference there would be in 

 the results. I am led to think that, on the one hand, European 

 mountains exhibit physiographic aspects which express facts of de- 

 velopment closely parallel to those of other continents ; yet, on the 

 other, the ranges of Karpathian type are characterized by peculiari- 

 ties not yet observed elsewhere and incident to the recency of folding. 



The essential feature of the method of observation lies in the recog- 

 nition of a topographic surface, which may be a surface of mature 

 hills and valleys or a smoother peneplain, but which is older than the 

 present cycle of erosion and has been warped. Originally a lowland, 

 such a surface may be depressed and become buried beneath sedi- 

 ment, or may be raised and consequently eroded. In the former case 

 the age of the sediments defines the epoch of warping ; in the latter 

 the degree of erosion gives some measure of the lapse of time, and 

 the valley-forms yield data regarding the steady or intermittent 

 nature of the uplifts. The depressed areas may be called downwarps 

 and the uplifted areas upwarps, in distinction to the analogous struc- 

 tural terms "syncline" and "anticline." No genetic relation is known 

 to exist between warped forms of the surface and structural forms of 

 the internal strata. 



