THE MAXIMUM EXTENT OF PLEISTOCENE GLACTAFION 



351 



be substantiated and, but for the problems of vast area and scarcity of workers, 

 these contentions would never have been proposed until systematic research 

 had been completed. However, controversial and hypothetical discussions 

 are healthy aspects of research and a somewhat premature publication can be 

 justified provided the facts are separated from the hypotheses and the limita- 

 tions are adequately stressed. In this manner some directive for future study 

 might be developed which would lead to the careful testing of the hypotheses 

 in critical areas. 



Fig. 10. Mature mountain-top detritus on gentle slopes above 700 m inland of Cape 

 Dyer, southeast Baffin Island. (Photo by G. Falconer, September 1961.) 



Little more can be said about the origins of the mountain-top detritus 

 except that a relatively long time was required for its development. In this 

 respect the author cannot go as far as Dr. Dahl in his conclusion that the 

 existence of mature detritus indicates the preservation of ice-free areas 

 throughout the Pleistocene. The mantle could be largely a relic of Tertiary 

 weathering processes, but the erratics in the Torngat and Kaumajet Mountains 

 indicate that if this is so, then it has been overridden by glacier ice sometime 

 in the past. In certain circumstances thin ice patches may well have developed 

 over mountain-top detritus and, because of limited ice movement, the 

 detritus may have been preserved underneath without modification. This has 

 undoubtedly occurred in Baffin Island, and a study of air photographs has 

 revealed instances where inature detritus is today emerging from beneath 

 such thin plateau ice caps and ice patches. However, the emplacement of 

 erratics on the high summits in northern Labrador demands a vigorous 

 movement of ice across them. It is inferred that tiie summits must have been 



