THE MAXIMUM EXTENT OF PLEISTOCENE GLACIATION 



349 



important sub-stadial significance. Whatever the true stratigraphic position 

 of the Clyde and Cockburn moraines, it seems certain that, as in northern 

 Labrador, extensive coastal tracts remained ice-free during the Classical 

 Wisconsin equivalent, and possibly throughout the entire Wisconsin stage. 



From the foregoing discussion the question arises as to whether or not 

 potential ice-free areas can be correlated with the occurrence of mountain-top 

 detritus. Few observations have been made in Baffin Island, although Gribbon 



Fig. 8. The outer part o( Sam Ford Fjord in the general vicinity of Clyde, Baffin 

 Island. In the middle right prominant lateral glacial terraces can be seen which may 

 be related to the Clyde lateral moraine system. In this instance their altitude is 

 about 300 m above sea level. Above them mature detritus is abundant as can be 

 seen in the foreground. (Photo by G. Falconer, September 1961.) 



has described mature mountain-top detritus on summits above 700 m in the 

 vicinity of Cape Dyer (Gribbon, 1960, and pers. comm. 1961). Similarly, 

 Falconer has made summit landings by helicopter for the Geographical 

 Branch in the Cape Dyer and Clyde vicinities, and has had occasion to examine 

 mountain tops from the air on southern Bylot Island. In each case it seems 

 likely that mature mountain-top detritus occurs (Fig. 8), ahhough this has 

 yet to be firmly substantiated (Falconer, pers. comm. 1961). Finally, lying off 

 Hall Peninsula in southeastern Baffin Island are two groups of small islands. 

 Lady FrankUn and Monumental islands. They are situated about 45 km off the 

 coast and rise precipitously to heights exceeding 200 m. Figure 9 is a photo- 

 graph of the summit of Lady Franklin Island taken from a helicopter. Light 

 snow limits the value of the photograph and no scale is available, although 

 it can be seen that the cliffs fall sheer to the sea. The appearance of mountain- 

 top detritus is striking, and the Hydrographic Service officer who had been 



