EROSION AND THE SUMMIT LEVEL OF THE ALPS 31 



has begun its work, stands perfectly still after its first elevation 

 or deformation" (p. 203), thus perhaps implying rapid elevation; 

 but only for "the sake of simpHcity." 



In an article on "The Development of Certain English Rivers"^ 

 the opening of a cycle of erosion was suggested by the words: 

 "Let gradual and intermittent elevation replace depression"; then 

 the establishment of consequent rivers on the slowly emerging sea 

 bottom follows. In a general discussion of "The Geographical 

 Cycle "^ upheaval without erosion is given first consideration; but 

 after allowing a page to a mere outline of the erosional changes 

 that ensue, it is explained that the outhne must be gone over again 

 to fill in details. The first of these is the correction of the too 

 simple assumption of rapid uplift : " It should not be impKed . . . . 

 that the forces of uplift or deformation act so rapidly that no 



destructive changes occur during their operation Even 



during uplift, the streams that gather in the troughs as soon as they 

 are defined do some work, and hence young valleys are already 

 incised when uphft ceases" (p, 487). Then after giving several 

 pages to a fuller account of the erosional changes during an uninter- 

 rupted cycle, certain complications are briefly considered, and 

 one of these is that all kinds of upheavals must be considered; 

 "such movements must be imagined as small or great, simple or 

 complex, rare or frequent, gradual or rapid " (p. 499). The manifest 

 reason for not then going on to give detailed discussion of these 

 various kinds of movements is that a good number of pages had 

 already been occupied in explaining a simple uninterrupted cycle 

 introduced by a relatively rapid elevation, and it may be added that 

 such explanation was needed because even that simple scheme was 

 thien essentially novel to the readers to whom it was addressed. 

 The complications of the scheme were, therefore, merely mentioned 

 instead of being elaborated. 



Complications of the erosion cycle. — "The Complications of the 

 Geographical Cycle" were, however, made the subject of another 

 article a few years later,^ in which it was said : 



^ Geogr. Jour., Vol. V (1895), pp. 127-46. 



=> Ihid., Vol. XIV (1899), PP- 481-504. 



^ Proc. Internal. Geogr. Congr. (Washington, 1904), pp. 150-63. 



