64 GEOLOGICAL NOTES ON KOSCIUSKO, 



The data, however, ah^eady quoted show that the limit of time 

 may lie somewhere between 3,000 and 10,000 years from the 

 present. 



The wonderful freshness of the grooves on some of the "dressed" 

 surfaces and roches moutonnees, west of Lake Merewether, Kos- 

 ciusko, in positions where the rocks could not have been sheltered 

 by moraine material proves that the glaciation was in a geological 

 sense comparatively recent 



We would here like to emphasise the opinion that it is out of 

 the question to refer either the Hedley Tarn glacial epoch or the 

 Lake Merewether glacial epoch of Kosciusko to Tertiary time. 

 We are strongly of opinion that these epochs belong to the Post- 

 Tertiary. If, however, later examination proves that there was 

 a much earlier and far more extensive glaciation which affected 

 the whole of the Kosciusko Plateau and extended even as far 

 down as Lake Coolamatong near Berridale (Plate vi.), (about 

 2,500 ft. above the sea) as one of us (Mr. Helms) thinks, it is 

 quite possible that this older glaciation may belong to Tertiary 

 time. 



(/) As regards the position of the snow line at Kosciusko at 

 the maximum extension of ice during the earlier of the two 

 glacial epochs (of the existence of which we have definite proof), the 

 present mean temperature of Kosciusko may be taken to be about 

 35° Fahr. At the sea-level, in the latitude of Kosciusko, 

 the mean temperature would be about 59° Fahr. At a rate of fall 

 of 1° Fahr. for 345 feet a mean temperature of 32° should be 

 reached at Kosciusko at about 8,200 feet. (The present level at 

 the summit of Kosciusko is 7,328 feet). During therefore 

 the earlier glaciation of the two comparatively recent glacial 

 epochs at Kosciusko, as the ice came down to about 5,500 feet 

 above the sea, the snow line may have been lowered from 8,200 

 feet to about 5,500 feet (though of course the glaciers of Kos- 

 ciusko, like many modern glaciers, may have descended below 

 the snow line). This would have meant a lowering of the snow 

 line to the extent of from 2,200 to about 2,700 feet, equal to a 

 lowering of the mean temperature by about 6J° up to about 8°, 

 and if Lake Coolamatong near Berridale be glacial, the level 



