and Igneous Rocks of Ensay. 123 



inetamorphism, is not at all new. Among others, Mallett 

 worked it out to a great extent, and it seems to be now gaining 

 ground among geologists in a somewhat modified form. The 

 views which I have now recorded have been slowly forced 

 upon me, so to say, during the progress of my investigations 

 into the geology of the Gippsland Alps during many past 

 years. If they have a foundation of truth, they will be 

 maintained ; if otherwise, then, no doubt, justly they will fall 

 to the ground. It is well that I should mention that I have, 

 in formulating them, relied upon more than the evidence of 

 the Ensay district alone. I have, to some extent, been 

 influenced by evidence as yet unrecorded from the Omeo 

 district. It might perhaps be thought that it would have 

 been better to have waited until that evidence had been 

 worked out, and laid before this Society. But in working 

 out the Ensay evidence I found that I had before me just 

 those problems in miniature which confronted me at Omeo on 

 the large scale, and I therefore briefly sketched the results 

 arising, not only from my Ensay work, but also from tfyat 

 in the Omeo district. Since the work which relates to the 

 latter area consists mainly in the analysis and microscopical 

 study of rocks collected there, it is not likely that the general 

 conclusions to which the field work has led me will be in any 

 great degree altered. 



Conclusions. 



The general results arrived at in the preceding pages may 

 be shortly summed up as follows : — 



(1.) Two kinds of metamorphism may be distinguished — 

 dynamic metamorphism, or the effects produced by heat, 

 resulting from vast movements within the earth's crust, 

 upon the sediments and the mineralised waters included in 

 them ; and contact metamorphism, or the effects produced on 

 the sediments by masses of intrusive igneous rocks. 



(2.) At the close of the Silurian age the sedimentary crust 

 of the earth was tilted, folded, and crushed over an enormous 

 region in the Australian Alps. 



(3.) The sediments were metamorphosed during these 

 movements. They were generally converted into argiUites, 

 and where the movement was greatest into mica schist and 

 gneiss. The Ensay area is an instance of the latter. 



(4.) Connected with or following these results of dyna- 

 mical metamorphism, the more or less altered sediments 



