BY PROF. DAVID, RICHARD HELMS, AND E. F. PITTMAN. 31 



^girine. Mr. G. W. Card, A.R.S.M., F.G.S., determined the 

 latter mineral for us. The nepheline is in beautifully developed 

 idiomorphic to hypidiomorphic crystals, showing perfect rect- 

 angular or hexagonal outlines in thin sections. Sanidine is 

 present in long delicate acicular crystals, singly twinned. The 

 rock is therefore essentially a phonolite. Sedimentary rocks, 

 as shown on the map (Plate iii.), are represented by slates, 

 phyllites, and felspathic quartzites, which are very possibly of 

 Lower Silurian age. No fossils, however, macroscopic or micro- 

 scopic were observed in them by us. We would add that the 

 frequency of earthquake shocks in the neighbourhood of Cooma 

 (see appendix, 51) indicates that crustal cracking and orogenic 

 movement is probably still in progress in this region. 



III. Evidences of Glacial Action. 



These may be grouped as follows : — 



1 . Smoothing of rock surfaces. 



2. Roches inoutonnees. 



3. Grooved and striated rock surfaces and striated boulders. 



4. Erratics and perched blocks. 



5. Terminal and lateral moraines. 



6. Lakes and tarns of glacial origin. 



As regards No. 1, Professor Lendenfeld has. already noted that 

 the rocks of gneissic granite at the Wilkinson Valley, near Kos- 

 ciusko, and at "Tom's Flat" (Thompson's Flat), near Pretty Point, 

 are smoothed and hoUowed-out in a manner very suggestive of 

 glacier action (11,12); and one of us (Mr. Helms) has already 

 commented on the fact that from Mount Kosciusko down to the 

 level of Boggy Plains, the granite surface over a large area shows 

 evidence of having been planed down by glacier ice ( 7 )• 



The recent examination by us of part of the Kosciusko high- 

 lands has confirmed these opinions as to the general smoothing of 

 the rock surfaces in the Kosciusko region between altitudes of 

 7,150 feet and 5,600 feet. 



In a paper of an introductory character like the present, it may 

 be convenient to describe these evidences in the order in which 



