THE MAXIMUM hXTENT OF FLEISTOCENL GLAC iATiON 



343 



by at least this amount. Despite this, the loss of elevation towards the north is 

 still significant and it is tempting to relate it to the juxtaposition of the moun- 

 tains and the broad and deep Hudson Strait which must have acted as a 

 major discharge channel for the inland-ice. 



With the exception of the evidence already presented indications of glacial 

 activity above the trim line in the zone of mountain-top detritus is entirely 

 lacking (Figs. 4 and 5). Coleman, Daly and Loken all maintain that the trim 



Fig. 4. An "old"' weathering surface: mature mountain-top detritus at 1050 m 

 west of Saglek Fjord in the Torngat Mountains. (Photo hv the author, August 



1957.) 



line is the upper Umit of glaciation within the area investigated by them, and 

 X-ray analyses by Dahl of fines collected by Loken from within the mature 

 detritus have led to the suggestion that their contained abundance of vermi- 

 culite, hydrobiotite and montmorillonite imply Tertiary, warm-climate weather- 

 ing processes (Loken, pers. comm. 1962). Figure 6 provides a provisional 

 picture of the distribution of mountain-top detritus. In Labrador the know- 

 ledge of its distribution is adequate for the formulation of a working hypo- 

 thesis as the strong correlation between occurrence of mature detritus and 

 altitude above present sea level is readily apparent. It is postulated, therefore, 

 that the detrital trim line marks the upper limit of a glaciation at one particu- 

 lar stage, although it is not yet possible to determine which stage. It is recog- 

 nized that this hypothesis is fraught with major difficulties and Hoppe and 

 Rudberg (pers. comm. 1962) have both maintained that altitudinai variation 



