BY PROF. DAVID, RICHARD HELMS, AND E. F. PITTMAN. 51 



grooving at the highest levels. Some idea of what this thickness 

 was may be formed from the height of the adjacent E. and W. 

 moraine previously described, its altitude being 6,550 feet, that 

 is 480 feet above Hedley Tarn. It may therefore safely be 

 assumed that the ice was at least 400 feet, perhaps 500 feet 

 thick, at the time when the glacier extended from Mount Tw^ynam 

 to Hedley Tarn, a distance of one and one-half miles. 



The small boulder exhibited was picked up b}'^ one of us 

 with its scored surface resting on the grooved surface of the 

 granite beneath at a point about 100 feet above the level 

 of Hedley Tarn. Hedley Tarn, like Lake Merewether, owes its 

 origin chiefly to a terminal moraine, or rather to what appear to 

 be four closely packed terminal moraines. It is much shallower 

 than Lake Merewether. Its general appearance is shown on the 

 photograph exhibited ; the granite promontory on the left being 

 grooved up to the highest limit shown in the photograph. The 

 nature of the terminal moraine dam is shown. The terminal 

 moraine has four ridges, each doubtless marking a pause in 

 the retreat of the glacier. They are slightly curved, with the 

 convex side directed down the valley. They are formed 

 almost entirely of blocks of slightly foliated granite, from one foot 

 or so up to 10 or 15 feet, or even more, in diameter. There is 

 not now much sandy material between the blocks, which, on the 

 lower side of the moraines, facing the Snowy River, form a 

 rugged belt of huge boulders, difficult to traverse even on foot, 

 the deep hollows between being largely concealed from view by a 

 growth of shrub. This moraine has already been described by 

 one of us (R. Helms, 7, p. 359). 



The base of the lowest bank of this moraine material lies at a 

 level of about 5,810 feet, whereas the top of the same bank has 

 an altitude of 5,950 feet, showing a thickness for this lowest 

 and oldest moraine of about 140 feet. 



This level of 5,810 feet marks the lowest limit down to which 

 undoubted evidence of glacial action has been found as yet in the 

 Kosciusko region, about 1,500 feet below the summit of Kosciusko, 

 the altitude of which is 7,328 feet. 



