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THE GEOGRAPHICAL STGXIFICAXCE OF FLOODS, 

 WITH ESPECIAL REFERENCE TO GLACIAL 

 ACTION. 



By E. C. Andrews, B.A. 



(Plates xliv.-xlv.) 



Introduction. 



The finding of a principle is necessary for scientific advance- 

 ment : with its clear understanding one marvels that the explana- 

 tion of certain natural phenomena has been concealed so long. 

 Nevertheless, although every natural law so far discovered is 

 excessively simple in its operation, a comprehensive, as against a 

 micro.-: copic, view is needful, otherwise the grand simple and 

 central fact may be missed in the maze of attendant details. 

 The case is analogous to that in which the names of territories 

 or continents printed in large type across maps are missed owing 

 to the focussing of the eye on the minute details; similarly, novices 

 experience difficulty in grasping the principle of the steam engine 

 when confronted, for the first time, with a near view of the 

 subsidiary parts. Apparently the case of stream-development is 

 no exception. The belief that streams have, in the majority of 

 instances, carved their containing valleys; that sea-currents have 

 moulded the shoreline curves; and that glaciers have, to some 

 extent at least, modified the preglacial valley-contours, is very 

 widely entertained; nevertheless the significance between extreme 

 flood and drought stages appears to have been strangely over- 

 looked. The great difference in the work performed during these 

 extreme phases of stream-action may have been frequently 

 admitted, but the application of the principle has not been 

 seriously considered. Thus, are we to consider the work of the 

 normal stream or that of the mighty flood as our unit in estimat- 

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