BY DR. W. N. BENSON. 37 



Lroad glaciated bar follows, beyond which the stream 

 falls diiectly into Rodway Gorge, which is a water-cut can- 

 yon. The boundary between the glaciated and water-cut 

 surfaces is sharply rnarked. To the south, the main basin 

 was extended by a cirque, cutting back into the soft 

 Permo-carboniferous rocks of the ridge joining Cradle 

 Iaz. and Mt. Brown. This cirque, however, does not 

 contain a lake, and is separated from Lake Rodway by a 

 long moraine. 



In the period of maxim^um giaciation, this great 

 trough must have been filled to overflowing with ice, which 

 was more than a thousand feet deep. Overflow-glaciers 

 made their way over the northern rim cf the trough, bear- 

 ing boulders of dolerite, nov scattered erratically. Once 

 over the ridge, they broke up, fell down into a small 

 gorge, were more or less recemented there, and, joined by 

 the overflow-glacier from near the outlet of Rodway 

 Lake, they scooped out a little rock basin before finally 

 failing into the canyon proper. This little basin may be 

 aptly named the Hidden Lake. The passage of the over- 

 flow-glaciers has cut the northern ridge, bounding the great 

 trough, into a succession of cross-ridges of quartzite and 

 hollows cut in mica-schist. 



North of Ctadle Mt. lies Dove Lake, a deep rock 

 basin formed by the enlargement by glacial erosion of the 

 upper part of the Dove River. The ice from the plateau 

 cind the north-western face of Cradle Mt., a total area 

 af about 1,000 acres, collected in the head of the stream, 

 passed down a steep fall on to a "tread" 400ft. below the 

 I'lateau, where Lake Wilks was cut out. A second tread 

 was formed near the lake-level, after a further fall of 

 about 300ft. The further effect of the ice is shown by 

 the soundings. (These were measured from a raft in a 

 strong breeze, and must be considered as rough approxima- 

 tions only, both in depth and position.) The upper end of 

 • lie lake is a basin at least 108ft. deep, separated from a 

 basin pJmost 200ft. deep by a quartzite ridge (at one 

 point only 72ft. deep, but rising into islands). The shal- 

 low point (48ft.) beyond the second basin probably marks 

 a. ridge connecting the quartzites of the great promontory 

 with those of Mt. Campbell, on the opposite side of 

 the lake. Beyond it is another deep (144ft.), separated 

 by a quartzite ridge and islet, from the westernmost basin 

 (-^Gft.), in which the Dove River ice was joined by the 

 cverflo'W from Crater Lake. The outlet stream passes 

 over a drift-covered plain, probably concealing a rock-bar. 

 Further soundings of this lake are very desirable. 



