52 E. C. ANDREWS 



The magnificent basins, lower cliff slopes, cirques, etc., due to ice- 

 action as compared with basins, banks, etc., cut by water, are due to 

 the fact that in the case of the latter the corrading agent occupied 

 an insignificant portion only of the canyon, while in the case of the 

 former the glacier occupied the whole of its valley. 



Too great emphasis cannot be laid on the fact that these features 

 are those which might be expected in areas of former high plateaus 

 in which profound canyons had been excavated during preglacial 

 times, and in which valleys marked convergence is a characteristic. 

 Such areas as the Alaskan, Norwegian, Patagonian, and New Zealand 

 fiord and canyon regions, the Rockies, the Sierras, the Alps, etc., 

 appear to answer this description. In these localities occur the forms 

 predicted on the theory of modification by an ice-flood. 



But in areas belonging to the late-maturity or early old age of 

 stream-erosion, also in areas of very unstable structures the resultant 

 forms will be less strongly marked. 



The influence of a continental ice-sheet during the ice-flood is 

 not here discussed, the writer not having visited such a region. The 

 resultant forms, however, could be predicted according to the degree 

 of stream development attained in preglacial times, and to the length 

 of time occupied in ice-cutting. 



APPENDIX 



AN APPEAL TO "GRADING" AS AN EXPLANATION OF THE PRESENT NEW 

 ZEALAND FIORD, LAKE, AND CANYON CONTOURS 



It may now be confidently asserted, as shown in the author's earher 

 reports, that the fiords, lakes, and canyons in New Zealand — as doubt- 

 less also those of Alaska, Norway, Patagonia, etc. — were due, in the 

 main, to preglacial stream-action, and have since been profoundly 

 modified by some mighty agent. The problem then reduces itself 

 to : What is the origin of such striking dissimilarity of topographic 

 contours in fiords and typical steam-developed canyons ? The pres- 

 ent note ascribes "fiord" topography to ice-streams in high flood 

 (i. e., glacial period) flattening their grades, and excavating deep holes 

 at points of marked canyon convergence. 



All streams, of whatsoever material composed, seek to approximate 

 to main baselevcl as quickly as possible, but in so doing they are com- 



