BY K. c. andrp:\v.s. 823 



the points of heavy gravitative thrust are the major discordances 

 of channel-grade, howsoever initiated. Now, from considerations 

 of eartli-relief these are seen to be common only in Alpine or 

 similar regions v*'here torrent-tracks and marked canon- 

 convergences abound. Glacial contours should therefore be 

 expected to reveal their magnificence in such regions, and be 

 reduced almost to vanishing point when traversing regions of 

 gentle relief. 



We shall see how applicable all this is when discussing 

 corrasion by an ice-sheet. 



S.European Alp s. — As with the New Zealand Alps, the 

 Californian Sierras, and the Canadian Rockies, so we should 

 expect certain land-forms in the European Alps. The descriptions 

 of Brigham (2), Davis (9a), Garwood (14), Penck (22) and others, 

 have enriched our knowledge of this region. Each of such forms 

 should be studied in connection with geologic structure, preglacial 

 canon-convergences, and cailon-broads or narrows. In studying 

 glacial convergence one must not be altogether guided by the 

 disposition of the lower canon-base; he must consider the canon 

 as a whole, otherwise he will be led into serious errors. 



For the European Alps, Garwood's excellent photographs 

 reveal forms precisely similar to those expected by the writer on 

 the assumption of the ice-flood hypothesis. 



c. ^Areas t^xiversed by a Continental Ice-Sheet. 



Imagine an ice-sheet covering all or almost the whole of a 

 large land-area. It is immaterial for our purpose whether the 

 sheet forms at one or more centres. In the case of several 

 centres the meeting-points are those, apparently, of reduced 

 energy so far as external glacial work is concerned. The 

 problem then resolves itself into one of a broad knowledge of pre- 

 glacial topography. 



i. Suppose the ice-sheet to descend an area of excessively 

 rugged topography. The forms described under headings A and 

 B should now be looked for. The less rugged the land-masses, 

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