Art. XIII. — The Age of the Metamorpluc Rocks of North- 

 Eastern Victoria. 



By J. W. GREGORY, D.Sc, F.R.S. 



[With Plates XIX.-XXI.]. 

 (Eead 11th September, 1902). 



I. — Introduction. 



The geological history of Victoria is generally represented as 

 beginning in the ordovician (lower silurian) period.' This 

 view is based upon the belief that the broad areas of schists 

 and metamorphic rocks in the extreme west, and in the 

 north-east of Victoria have been formed by the metamor- 

 phism of silurian and ordovician rocks in post-silurian times. 

 This view is repeatedly expressed in the geological literatui'e of 

 Victoria. Dr. Selwyn attributes such an origin not only to 

 the schists, but even to the granites. He stated'-* that the 

 " granites are in no sense intrusive or irruptive masses, but only 

 the completely-transmuted ends of the silurian rocks that have 

 either been lowered in early geological times to within the in- 

 fluence of central heat, or by some means been subjected to other 

 powerful transmuting agencies."^ 



The same theory is taught in Mr. R. A. F. Murray's "Physical 

 Geography and Geology of Victoria" (pp. 37, 38); and Mr. 

 A. W. Howitt lent the weight of his authority to this view by 

 maintaining the existence of a passage from silurian sediments to 

 metamorphic rocks in various parts of the Victorian Alps. In 

 Mr. Howitt's later papers this view was re-considered in so far 

 that the felspathic metamorphic rocks were regarded as altered 

 plutonic rocks, and only the iion-felspathic schists as altered 



i_Exclusive of a small band near Heathcote, that has been described as Cambrian. 



2 Spec. Rep. Geol. Surv. Vict, 1892. 



3 A. R. C. Selwyn : Notes on the Physical Geography, Geology and Mineralogy o( 

 Victoria. Internat. Exhib. Essays, 1866-1867, p. 155, Official Record, Melbourne, 1866. 



