116 The Sedimentary, Metamorphic, 



the relations of the three great groups of sedimentary, 

 metamorphic, and massive intrusive igneous rocks. 



The Relation of the Rock Masses to Each Other. 



At Ensay, as elsewhere in North Gippsland, the oldest 

 rocks which can be discovered are members of the great 

 series of auriferous argillites and sandstones, which is with 

 fair certainty referable to the lower Silurian age. When a 

 lengthened section is examined in almost any tract in the 

 Gippsland mountains, it soon becomes clear to the observer 

 that these sediments were once continuous in a crushed 

 and folded condition throughout, but that by the combined 

 action of faulting, denudation, and erosion, this continuity 

 has been broken, so that while in places the whole country, 

 down to some given datum line, shows no other formations 

 than these tilted and slightly metamorphosed sediments, in 

 other places their merest traces remain as distorted and 

 fractured contact schists attached to the massive plutonic 

 rocks which have invaded them. 



In other papers upon the geology of North Gippsland I 

 have insisted upon the clear evidence there is that the 

 plutonic rocks have disturbed and metamorphosed the 

 Silurian sediments, and to a greater or less extent melted off 

 and absorbed, not only the lower part of the folds into which 

 they had been previously forced, but also, so far as is yet 

 known, every portion of the older formations, whatever 

 they may have been, upon which they were laid down. 



It is possible to note, by a few striking geological features, 

 the sequence of the terrestrial movements which are in- 

 dicated by the folding and crushing together of the Silurian 

 sediments, their metamorphism and invasion by plutonic 

 rocks, their denudation, and the subsequent laying down 

 upon them of other formations, both sedimentary and 

 volcanic. 



In North Gippsland the Silurian formations, as a whole, 

 have been folded more or less sharply together. The next 

 succeeding sediments — namely, those of Middle Devonian 

 age — have not been so generally and regularly affected ; for 

 while at Tabberabbera the beds have been folded much as 

 have been the Silurians, the limestones of Buchan or Bindi 

 remain comparatively level, as compared with the acutely 

 folded older strata adjoining and inferior to them. 



