38 GEOLOGICAL NOTES ON KOSCIUSKO, 



That the whole moraine, as well as the rock surface to the N.E. 

 on which it originally reposed, has undergone an appreciable 

 amount of erosion, since the disappearance of the last of the 

 glaciers is proved b}^ the evidence shown in Plate iv. 



Careful measurements convinced us that not less than 9 feet 

 (measured vertically) of moraine and 10 feet of phyllite have 

 been eroded since the retreat of the ice, and this has led to the for- 

 mation of the small gully which bounds this lateral moraine on the 

 N.E. A total lowering of the surface, therefore, to the extent 

 of at least 1 9 feet has taken place since the disappearance of the 

 last of the ice. The evidence afforded by the erosion of this 

 small gully, at the side of the lateral moraine, was about the 

 best we were able to obtain as to the approximate date of the 

 latest glaciation at Kosciusko. It is, of course, impossible to 

 estimate the exact time- value of this erosion, but in this respect 

 we would quote the statistics recently obtained by Mr. C. C. 

 Brittlebank, F.G.S., for the rate of erosion of the Myrniong 

 Creek Valley, in Victoria."^ 



Mr. Brittlebank summarises (op. cit. p. 321) the results of his 

 observations as follows : — 



Rate of erosion in Werribee River and tributary creeks, 

 Victoria. 



Basalt ... 002 inches in 5 years = 1 inch in 250 years. 



Silurian ... 0*03 ,, ,, =1 ,, 166| ,, 



(Slates— T.W.E.D.) 

 Granite ... 0-04 ,, „ =1 „ 125 ,, 



Glacial ... 0-05 „ „ -1 „ 100 „ 



(Compact Permo-Carbonif erous mudstone with small glacial boulders — 

 T.W.E.D.) 

 The moraine at Townsend's Pass, Kosciusko, would no doubt 

 have been eroded much more rapidly than any of the rocks 

 studied by Mr. Brittlebank, and the time needed for its erosion 



* Austr. Association Adv. of Science, Melbourne, Jan. 1901. "The rate 

 of erosion of some river valleys." By C. C. Brittlebank. Geol. Mag. 

 No. 433. New Series, Dee. iv. Vol. vii. July, 1900, pp. 320-322. 



