3G A FURTHKR NOTE ON T}IK TcH'OORAPHY OK I,AKK FKNTON, 



times the line Field East — Sea,G:ei-'s Look Out — Monash — Maw- 

 son, was a continuous iMdjre, unbroken by the Fenton gap, 

 and thence the land sloped rapidly on the south to the Tyenna 

 Valley, and gently on the north to the Broad River, which had 

 by then captured the whole drainage of the top of the 

 plateau. 



During the earlier portion of the glacial epoch, the 

 bottom of the Broad River was considerably deepened, and 

 its sides made steeper. At the same time, the Lake Nicholls 

 cirque, at the head of the Russell Falls Creek, was being 

 eroded, and in the deeper bed of the Lady Barron Falls 

 Creek another cirque was eating into the hillside. The pre- 

 glacial creek bed had probably cut well into the mountain 

 mass, and the intense frost action widened this valley, and 

 cut a huge amphitheatre into the side of the hill. 



As the nivation layer rose, and while it was cutting out 

 the Dobson and Seal cirqies and the cirque at the head of 

 the Broad River, it was also cutting a similar cirque into 

 the northern side of the ridge between what are now Seager's 

 Look Out and Mt. Monash, and opposite the cirque at the 

 head of the Lady Barron Falls Creek mentioned above. 

 Thus two cirques cutting in end to end were gradually 

 narrowing the rock wall that connected the last-named pro- 

 minences. 



Evidently the southern cirque was capable of more 

 erosion, and was working deeper, than its twin on the other 

 side of the ridge. As the ice age waned, this cirque at the 

 head of the Lady Barron Creek shrank and operated at an 

 elevation of about 300 feet above the floor of the original 

 cirque; in fact, the nivation layer rose here, as in other 

 places. 



The southern cirque eventually ate right through the 

 ridge, and invaded the drainage basin of the northerly flow- 

 ing glaciers and streams. It cai-ved a small basin about 

 100 feet deep, a mile long and half a mile wide, cutting deep- 

 ly into the plateau mass, and thereby throwing the water- 

 shed a mile to the northward. It doubtles.s would have cut 

 a cirque as imposing as the Lake Seal cirque, but for the 

 fact that, since the old Broad River had eroded away the 

 land surface, there was no rock face left from which to 

 erode a cirque, and the result was a complete gap in the 

 dividing ridge. The glacier probably vanished earlier than 

 some others on the field, having eroded away most of the 

 catchment area for its snowfield. 



The larger and lower, earlier cirque can be clearly 



