CORRASION BY GRAVITY STREAMS. 265 



2. Moutonnees exhibited peculiar appearances; if large 

 they appeared to be abraded on the up slope, and heavily 

 quarried on the downslope. Actual deposition at times 

 was observed at the feet of the steep down slopes. (This 

 was at times due to the effect of later and less powerful 

 glacial action.) If small they were strongly abraded on 

 upstream slopes but in proportion as their downstream 

 slopes were steep, such actual slopes appeared to have 

 been protected from abrasion. Nevertheless, the down- 

 stream side had suffered by other methods of corrasion. 

 The condition producing this steep downstream slope on 

 small moutonnees appeared to be that of smashing and 

 quarrying by the glacier on the downstream edge of the 

 stoss-seit face, thus causing the lee seit to recede upstream. 



3. Where glaciers had passed round large masses of rock, 

 for example, a cliff summit presenting numerous large 

 irregularities of surface, where the whole mass would be 

 in the line of strong scour, and the ridge discussed would 

 have its axis in the line of general ice flow, there the ice 

 movements were most instructive. On a floor ending down 

 stream against a rock face, the ice scour had produced a 

 long deep sinuous groove along the line of least resistance 

 to stream flow. Guided by slope to the steep rock face 

 just described, the ice-made groove followed it clear up to 

 the summit [Fig. 11 (a)] because horizontal escape was 

 impossible. 



On passing from one high ridge to another both of whose 

 axes lay in the direction of main ice motion, and where 

 the higher ridge presented a broad vertical wall to the 

 lower upstream example, wall and ridge being separated 

 by a deep cross fissure passing on each side to the valley 

 depths below, there the ice grooves followed the general axial 

 direction of the lower ridge, but on meeting the cross ditch, 

 and opposing higher wall, they passed horizontally and 



