DALY: GEOLOGY OF THE NORTHEAST COAST OF LABRADOR. 241 



also aligned in series. In both cases the axis of symmetry and the 

 convex side of the curved pit were directed N. 55°— 60° E. What made 

 this locality of particular interest was the fact that one series of seven 

 furrows lay on the stoss side of a ledge covei'ed with undoubted glacial 

 stria? and grooves. These were seen to lie in the axis of the lunes. 

 The trend of the striae was likewise N. 55°-60° E. Such a relation of 

 parallelism between lune-axes and stria? was a strong witness to the 

 glacial origin of the lunes, and it was found to exist in the case of the 

 great majority of them at each locality on the coast. (See Table II.) 



The best exposures of the luues discovered during the summer are at 

 Pomiadluk Point, at Aillik Bay and at Hopedale. (Plate 7.) At the head 

 of Aillik Bay near the highest of the elevated shore-lines, a fine group 

 of naked, highly polished roches moutonnees are marked with numerous 

 lunes from two to three feet in span. On the east side of the bay at the 

 shore near the prominent trap dikes opposite Summer Cove, the serial 

 arrangement of the lunes is exceptionally well developed. In one 

 instance twelve, and in another fifteen, of them were seen in line. 



Single lunes, very rarely lunes grouped in series, are sometimes so 

 situated that their axes of symmetry are widely divergent from the 

 accompanying lines of striation. Such an attitude is, however, quite 

 exceptional, and in general, the perfection of the lunate form is greatest 

 when the axis of symmetry is orientated parallel to the stria? and 

 grooves. Like the latter, the lunes were found most commonly on the 

 stoss side of the glaciated ledge. As in Maine, the convex side of the 

 lune is always directed downstream with reference to the moving ice- 

 sheet that formed the grooves. This is true in the south and also at 

 Nachvak where the glaciation was but local. 



There seems to be no reasonable interpretation of the lunes that does 

 not assign their location to glacial action. But it is difficult to imagine 

 how either clean ice or boulders caught in the ice and dragged over a 

 ledge could produce the actual furrow. From a somewhat prolonged 

 study of the typical examples at Hopedale, the writer was led to believe 

 that these lunes were only potential when the ice-sheet disappeared and 

 to extend the same idea to all such furrows. The tension or shearing 

 stress set up in the bed-rock by a boulder dragged along beneath the 

 ice, must oftentimes be enormous. This must be so if boulders are 

 really responsible for the deep striation and grooving of glaciated ledges. 

 Such shearing stress may be easily conceived to be here and there partly 

 relieved by the development of incipient cracks dipping gently forward 

 and, at the same time, sloping inward from each side toward the line 



