36 



E. C. ANDREWS 



as in times of heavy water they struck each other and the containing 

 banks wildly until their shrieks could be distinguished above the 

 roar of the escaping waters. On the contrary, we expect the reduced 

 stream to gurgle among the flood bowlders, to override the banks 

 of debris, or to become stagnant even in the depressions. Thus the 

 recession of high water is seen to act in the direction of obliterating 

 the marks made by storm waters. 



Fig. II. — Sketch section across the Arthur River mouth. (From a photo.) 



Again, in proportion to the advanced degree of stream reduction 

 attained in any region, so are the flood forms just enumerated less 

 and less accentuated in areas of hard, solid structures. 



APPLICATION TO ICE- STREAMS 



If now the writer has succeeded in stating his case for stream- 

 action clearly, the far-reaching effects of its application to glacial 

 studies must be apparent at once. For it is indisputable that the 

 recent Ice Age marked a glacial flood, while the present insignificant 

 glacial representatives of that momentous period indicate a pro- 

 nounced ice-drought. 



Let us review briefly the probable action of glaciers in these pre- 

 glacial stream-developed canyons of southwestern New Zealand. 

 As a type of a valley developed by stream- action to the stage of late 

 youth or early maturity, the accompanying sketch of Moonan Brook 



