52 GEOLOGICAL NOTES ON KOSCIUSKO, 



An examination, however, of Evidence Valley further down 

 to its junction with the Snowy River Valley showed that the 

 rocks were much worn down in a manner very suggestive of 

 glaciation ; and as already mentioned, a few ice-scratched blocks 

 were found there by us down to an altitude of 5,550 feet. The 

 level of the junction of Evidence Valley with the Snowy Valley 

 is about 5,500 feet. At a point a little over one-quarter of a mile 

 up Evidence Valley from its junction with the Snowy is the 

 interesting dyke of phonolite referred to earlier in this paper. 



Betts^ Camp^ Porcupine Ridge, Thompson's Flat, Pretty Point, 

 Boggy Plains, and Valleys of Spencer's Greek and Perisher Creek. 

 — From Betts' Camp to Porcupine Ridge and thence via Thomp- 

 son's Flat to Pretty Point, and on to Boggy Plains, there occur at 

 frequent intervals small flats, 200 to 300 yards wide, the floors 

 of which are strewn with small boulders, tightly packed in thin 

 sandy clay, resting on a smooth surface of granite. To the S.E. 

 these flats, are terminated abruptly by slopes towards the Cracken- 

 back River, so steep as to be almost precipitous. In a N. by W. 

 direction they slope gradually down to the creeks which flow into 

 the Snowy River. 



The smoothing of the granite surface is not apparent at the 

 sides of these flats or on the intervening hills. 



On the assumption that these smoothed surfaces are of glacial 

 origin, it would appear that the glaciation must have been of 

 somewhat high antiquity, as the granite on the intervening hills 

 is weathered into large domes, pinnacles and tors. As regards 

 the boulders which are plentifully distributed over the floors of 

 these flats, they were in almost every case such as might have been 

 derived either from the local granites or enclosures in them, or 

 from dykes traversing the granite. A pyroxene amphibolite, in 

 places nearly approaching a hornblende andesite, and passing 

 through decomposition into a chlorite rock, was of frequent 

 occurrence. Clear evidence was obtained that they were derived 

 from dykes intersecting the granite. A great number of these 

 boulders, which varied from a few inches up to 2^ ft. x 1 ft. 8 in. 

 X 1 ft. 3 in. in diameter, were examined by us. In most cases 



