54 E. C. ANDREWS 



either efficient corrasion or transportation. The diminished glaciers 

 would now be compelled to cease corrading at these points of flood 

 scour and aggrade here until a working grade could be set up or 

 another flood return to carry on its work. 



Glaciers of the present ice drought should, therefore, lie inactive or 

 stagnant along these flood-holes (i. e., fiord, canyon and lake basins), 

 while overriding of moraines without transportation and aggrading of 

 flood-holes would set in. 



Such were among the theoretical conclusions^ of the author after a 

 preliminary tramp through New Zealand and a comparison with eastern 

 Australian stream channels. This idea suggested the possible existence of 

 ' ' facts of form ' ' unnoticed during the first short excursion to the Sounds, 

 but nevertheless absolutely necessary to the success of the theory. 



Opportunity was found later to examine Milford Sound while the 

 idea was framing itself, and the forms sought were found. Thus in 

 the strong crystalline schists of the famous fiord, the canyon walls, just 

 below the convergence of the magnificent Cleddau and Arthur valleys, 

 5,000 feet deep, show steep upper slopes with marked undercutting up 

 to great heights above the fiord base, an alignment of walls, absence 

 of spurs, and an enormously deep rock basin. Just here a third and 

 fourth canyon enter the narrow main channel, and the undercutting, 

 with production of hanging valleys cut off by a great rectilinear wall, is 

 very pronounced. Nothing could be more suggestive of rock basins 

 excavated by ice-floods at canyon convergences than the old steep lat- 

 eral channel grades of these "hanging valleys" now separated by 

 vertical cliffs, due to undercutting, from the flattened grade of the 

 main channel. Still lower down no side canyons come in, and the 

 fiord soon shows a decided reversal of channel grade. 



All this points to the work of a flood or of floods during the youth 0} 

 glacial attack. This idea of youthful ice-attack, exemplified by fiord 

 and canyon contours in strongly glaciated regions was first advocated 

 by Professor W. M. Davis. 



Subsidence thus appears to be practically negligible in forming 

 present fiord depths. 



' Other deductions made were the necessity for absence of this tremendous exca- 

 vation at marked canyon divergeiues ; and other points noted in main report. All 

 these appeared to be satisfactorily seen at Lake Wakatipu, Preservation Inlet, etc. 

 Dr. G. K. Gilbert's observation of lack of glacial erosion in Annette Island, Alaska, 

 appears to be a case in point. 



