GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 49 



previously pointed out, a small amount of ground moraine escapes from being 

 carried across the valley and moves down in the left lateral of Lefroy. In 

 addition to this there is a large detrital cone, with its base resting upon the 

 ice, and slowly dealing out morainic material as the ice moves down the valley 

 (plate iv, figure 2). The covering of the general surface of the lower Victoria with 

 rock debris prevents a great amount of differential melting, so that the lateral and 

 medial moraines attain no great height. 



c. Medial moraine. Owing to the stream-like nature of the flow, the left 

 lateral of the Lefroy and the right lateral of the upper Victoria unite at the nose 

 of Mt. Lefroy into a single medial moraine. This is at first a poorly defined 

 ridge, but it becomes higher and broader as it moves across the valley from 

 which emerges the tributary and serves as a divide for the two main drainage 

 systems (plate iv, figure i). Owing to the small volume of ice delivered to the 

 Victoria by the double tributary, the medial moraine lies close to the right lateral, 

 being separated at first by a deep depression, shown in plate xv, figure 2, which 

 gradually disappears below as the two moraines merge. The western slope of the 

 medial becomes long and gradual in the lower part. The entire length of the 

 moraine is about 7,500 feet. Toward the nose it broadens as shown upon the map 

 and in plate iv, figure i and becomes poorly defined, implying a sluggish condition 

 of the ice upon which it rests. Its crevassed condition in the neighborhood of the 

 line of plates was described upon page 37. Owing to the source of the material 

 above noted the moraine contains a certain amount of ground-morainic material, 

 but the bulk of it is angular and consists of quartzites, sandstone, schists, 

 dolomite, and limestone. Some of the blocks show algae, tracks, lingulas, and 

 bryozoan-like stems. It has practically all been derived from Mt. Lefroy. 



d. Terminal moraine. Although the front of the ice at the nose is in a con- 

 dition of halt, the ice is practically stagnant and no frontal moraine has yet been 

 formed (plate v, figure i). Along the oblique ice front the retreat has been gradual 

 enough to distribute the superficial and englacial rock debris somewhat uniformly 

 over the valley floor and there has thus been formed no prominent ridge, as shown 

 in plate vm, figure 4. The apparent heaps seen at the right, alongside the face, still 

 contain a core of ice, which will eventually melt and allow the rock to settle upon 

 the valley floor. A small ridge, from 100 to 125 feet back from the ice, indicates 

 a somewhat recent short period of halt, perhaps but one or two decades ago. 

 It is quite probable that this halt was contemporaneous with that of the Illecille- 

 waet, which closed in 1887. Between the oblique front and the nose conditions 

 have been favorable for the formation of a somewhat poorly defined terminal 

 moraine, i. e., the front has been in a condition of halt while the ice was moving 

 forward and dumping its load of angular debris. Two of the ridges that pass 

 across the glacier, just back from the nose, extend off the ice upon the terminal 

 moraine, without interruption, testifying still further to the sluggish condition 

 of the ice about the nose. The medial moraine has introduced some ground- 

 morainic material into the mass which has furnished a foothold for vegetation. 

 Spruce and larch are climbing up the slope, the largest of the former showing 



