234 Davis — Framework of the Earth. 



changes that mountains have suffered by erosion during 

 and after their first deformation. If this phase of moun- 

 tain study found its application only in the explanation 

 of their present form, its omission from a treatise on 

 earth-crust structures would be proper enough, even 

 though the treatise be entitled "The Face of the Earth" ; 

 but the study of mountain forms, as the joint result of 

 deformation and erosion, has come in the last half-century 

 to be an important means of interpreting the disturb- 

 ances that the mountains have suffered. It has indeed 

 been thus learned that many mountains owe the altitude 

 they to-day possess not to the tangential deforming forces 

 by which their strata were first crushed, but to forces 

 of later date and simpler action by which, after the first- 

 deformed mass had been eroded to moderate relief at a 

 moderate altitude, it was upheaved with more or less 

 warping and fracturing and with no indication of tan- 

 gential compression, along lines that are not necessarily 

 coincident with those of its earlier disturbance. 



A single example of the manner in which erosional 

 studies bear upon deformational studies may be taken 

 from Suess's first volume, an example of all the more 

 importance because it illustrates a serious danger to 

 which the author of a work of compilation is exposed; 

 namely, that of accepting the conclusions of a distant ob- 

 server without means of testing their correctness. The 

 case in point is that of the supposed 40,000-foot fault 

 along the western border of the "Wasatch range of Utah, 

 as reported by King. Here Suess adopted King's 

 measure, without perceiving that, if a far-advanced cycle 

 of erosion be interpolated between the folding of the 

 Wasatch rocks and the faulting of the Wasatch range, 

 the measure of faulting may be reduced to a quarter or 

 less of King's extravagant estimate. As to the accept- 

 ance of conclusions reported by the many observers cited, 

 it is not to be questioned that Suess as a rule exercised 

 excellent judgment and sagacity; but as to the omission 

 of erosional processes from a study of the face of the 

 earth, this would seem to be because the physiographic 

 method of investigation employed in the interpretation 

 of these processes was not embraced in Suess's view of 

 geological science, and that he never acquired it. Ero- 

 sional processes were omitted because he did not under- 

 stand their application : and in view of their omission it 



