208 W.M.DAVIS NOMENCLATURE OF SURFACE FORMS 



sets of the corresponding ridges or cuestas will contradict this view and 

 prove that the scarps are due to erosion after renewed uplift of a faulted 

 and previously worn-down structure, and not directly to faulting. If the 

 scarps were due to recent faulting, the corresponding cuestas ought still 

 to stand nearly opposite each other on the two sides of the fault line. 

 But this interpretation of the case has a geological flavor, in that it turns 

 the attention chiefly to a succession of past events. A more geographical 

 interpretation is reached when the mere mention of scarps in such a 

 structure as fault-line scarps, either resequent or obsequent, at once 

 awakens attention to the probable strong offset of corresponding reliefs 

 on the opposite sides of the fault line. 



As long as any significant traces of the forms developed in a first cycle 

 are not obliterated by the erosion of a second cycle, they deserve explicit 

 description in a physiographic discussion, following the general prin- 

 ciple above stated ; and their description should introduce, in any fitting 

 order, a sufficient account of the faulted structure on which the forms of 

 the previous cycle were developed, the processes that developed them, and 

 the stage of development that they had reached when further progress was 

 interrupted by uplift; then the effect or amount of the uplift should be 

 stated, and finally the forms developed in the new cycle should be intro- 

 duced in their proper relation to the surviving forms of the previous 

 cycle. The omission of any one of these factors will leave the reader in 

 doubt as to what the writer has seen. 



With the advance of the neAv cycle even the hard-rock uplands will in 

 time be maturely dissected, then subdued, and at last worn down to small 

 relief in advancing old age; with these changes the newly developed 

 scarps will retreat and take on details of form according to the structures 

 revealed in them, after the fashion of retreating escarpments of what- 

 ever origin; thus the fault will again be topographically obliterated in 

 the resulting lowland. The forms of earlier cycle thus lose their impor- 

 tance and do not need mention after the maturity of the new cycle. 

 Eventually the uplands, hills, and scarps must all fade away, and a wide- 

 spread lowland, figures 1 H and 2 H, will stretch across the region. 

 Then or at any earlier stage uplift without faulting may again occur 

 and the systematic series of changes will be begun over again; yet dur- 

 ing all these physiographic transformations the fault is, geologically 

 speaking, a constant quantity. Or renewed faulting and differential up- 

 lift may take place along the former fault line, and thus introduce more 

 complex problems. Examples of this kind have been described by Hunt- 

 ington and Goldthwait ('04, 225) and by D. W. Johnson ('09, 151), 



