﻿48O SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 4/ 



ent name. This consists of a sharply defined heap of rock debris, 

 about 400 ft. long, placed at right angles to the main axis of the 

 valley and serving as a barrier (fig. 82). The lake has a double 

 outlet, mie across either end of this moraine, since with its flow 

 divided, short season and no sediment, it can accomplish almost 

 nothing in the way of deepening either outlet. The moraine in- 

 creases in height, rather gradually toward the west, attaining a 

 height of about 70 ft. and then ends abruptly, with no trace of a 

 continuance across the valley. This feature has led some to con- 

 sider the entire mass as a rock slide from the adjoining mountain 

 slope. It is, however, a moraine such as a piedmont type of glacier 

 is capable of making. This represents the place of halt of the front 

 of the most eastern component stream of the Wenkchemna glacier 

 at an earlier stage, the adjoining stream to the west reaching farther 

 down the valley and, very probably, making a correlative moraine. 

 The western end of this barrier moraine, while it was being formed, 

 abutted against a solid ice wall, the removal of which by later melting 

 allowed the debris to assume the " angle of repose." At the present 

 time the easternmost component stream of the glacier is still relatively 

 short compared with its neighbor and were the front to make a suffi- 

 cientlv prolonged halt there might be reproduced this same type of 

 moraine. 



6. Block Moraine. — Along the western front of the Wenkchemna 

 glacier, for a distance of over a mile, there occurs a tremendous 

 accumulation of huge morainic blocks of a red and brown sandstone, 

 much disintegrated by the weather, but each roughly maintaining its 

 own shape and size (pi. lxviii, a). Xear the upper end of the valley 

 it must be a half mile across, reaching from the present ice margin 

 to the foot of Pinnacle Mountain and surrounding the Wenkchemna 

 I .ake ( fig. 83 ) . Toward the east the moraine narrows up and an 

 apparently older portion is soil-covered and forested. Nearly oppo- 

 site Deltaform there is an accumulation of coarse, lichen-covered 

 blocks at the vd^v of the ice, apparently part of a massive moraine 

 which is overridden by the eastern half of the glacier. At the west- 

 ern side the ice has not been able either to mount this obstruction, or 

 to push it ahead, and has been deflected down the valley, as pre- 

 viously noted. At an earlier stage the glacier must have extended 

 quite across the valley and have been carrying a tremendous load 

 of fragments of the peaks to tin- south. The formation of the 

 moraine began, with which the ice continued in close touch, being 

 unable to either override, or push it ahead, and there resulted a 

 continuous deposit for a half mile, lint with relatively little height. 



