BY RICHARD HELMS. 351 



The only piece of rock I have seen that has retained its polish 

 I found about a mile and a quarter to the north of Mt. Twynam 

 on the southern side of a rugged peak surrounded by a number of 

 rocks of various dimensions. The block is about four feet long 

 and nearly square and lies with its polished surface upwards. 

 About the third of one corner of the surface has split off and 

 shows no polish, but the remainder is polished perfectly level, but 

 still shows a number of shallow pits where the polish did not 

 reach the original fracture-surface. The rock of this piece is a 

 very quartzose granite (syenite ?) quite dissimilar from the pre- 

 vailing rock, and evidently much harder, which accounts for the 

 retention of the polish. There are, however, no striee noticeable, 

 which is rather remarkable, as they are generally present on 

 glacier-polished surfaces. The beautifully striated and polished 

 specimens of quartzite from the head of St. Vincent Gulf I saw 

 in the possession of Prof. Ralph Tate at the University of 

 Adelaide are without doubt most characteristic examples of 

 glaciated rocks, and surpass all that have so far been found in 

 the Australian Alps. 



To what erroneous conclusions careless and superficial observa- 

 tions may lead one I have had the opportunity of judging during 

 my recent visit to these mountains.* 



Dr. R. V. Lendenfeld in "The Glacial Period of Australia"! 

 says : " Further proofs for the correctness of the supposition that 

 we have to do with the effects of ice are furnished by the relative 

 position of joints and surface. The polishing goes on of course 

 quite regardless of joints, and consequently in ninety-nine cases 

 out of a hundred one will find the polished surface cutting the 

 joints at varying angles, and not parallel to the direction of any 

 joints." 



This very feasible-looking supposition is, however, entirely 

 inapplicable to the rocks of the Australian Alps, where I found 

 a number of recent fractures going crosswise in almost every 

 direction imaginable to the joints, which, surprising as it is, seems 



* February, 1893. 

 + P.L.S.N.S.W. X. p. 48. 



