BY T. W. EDGEWORTH DAVID. 661 



(5) Lakes and tarns of glacial origin, together with alluvial 

 flats and swamps representing sil ted-up old lake-basins. 



(6) U-shaped valleys. 



(7) Hanging valleys. 



As regards evidence (1), Professor Lendenfeld has recorded the 

 fact* that the rocks at "Tom's Flat" (Thompson's Flat) are 

 smoothed and hollowed-out in a manner very suggestive of glacial 

 action (op. cit. p. 10, and Plate v.). 



Mr. Richard Helms, in his most valuable paper to this Society, f 

 has argued that the evidences of glacial action of this kind can 

 be traced as far down as Boggy Plains and the head of Wilkin- 

 son's Valley, that is almost to a level of 5000 feet above the sea. 



During my earlier examinations of Kosciusko Plateau it 

 appeared to me difficult to realise that areas such as, for example, 

 the Porcupine Ridge and Wragge's Camp, with their huge tors 

 and spines of granite, could possibly have been glaciated in recent 

 geological time. It seemed hard, too, to understand how 

 smoothed rock-surfaces, such as those studied by Lendenfeld and 

 Helms at Thompson's Flat, could have been glaciated by ice, 

 while within a few yards of the same smoothed rocks are granite 

 tors and blocks of granite, many feet in diameter, lightly poised 

 upon one another, the latter structure being obviously due to 

 prolonged weathering under conditions free from ice. These 

 apparent inconsistencies, it appears to me, are now explicable on 

 two grounds, viz.: — 



First, an obvious fact, which should have attracted my atten- 

 tion before in connection with the preservation of glacial 

 evidences at Kosciusko, is this, that where the snow is most 

 heavily drifted there the rock-surfaces are best protected from 

 the action of the weather. The presence alone of snow-drifts 



* Report on the Results of Recent Examination of the Central Part of the 

 Australian Alps, by R. von Lendenfeld, pp.l-J6, Pl.i.-vi., Govt. Printer, 

 Sydney, January 21, 1885. 



t " On the Recently Observed Evidences of an extensive Glacier Action at 

 Mount Kosciusko Plateau," by Richard Helms. Proc. Linn. Soc. N. S. 

 Wales, Series ii. Vol. vii. 1893, p.355 and PI. 18. 



