220 PROCEEDINGS OF SECTION C. 



Within the area thei'e are plutonic rocks and tracts of pressure- 

 schists, but almost all traces of the normal sediments which must 

 have once extended over it are denuded. On the western side, 

 however, these remain in great extent and unknown thickness, and 

 on the eastern side in somewhat less extent. These observations 

 suggest a great anticlinal arch of the crust at this place, even 

 allowing for faulting, which has evidently taken place very strongly. 



It seems to me, therefore, that the most reasonable explanation 

 is one which assumes that the earth stresses acted first in folding 

 and compressing the strata, and then in raising up the compressed 

 crust locally into a great north-westerly fold. 



The motive power must have been lateral pressure, and this 

 may well have been connected with an adjoining descending area. 

 The conception is then reached of an imprisoned igneous magma, 

 subjected to increased pressure and being thus forced against and 

 following the rising crust. 



The relations of the plutonic rocks which occur in extended 

 areas from Omeo to Dargo to adjoining formations, of the diorites 

 at Swift's Creek to the adjoining schists, and of similar intrusive 

 masses elsewhere in the district to the sediments, show that the 

 magmas were forced like wedges between the older fi-actured 

 rocks, and now fill wide spaces from which the sedimentary beds 

 have been thrust aside, or which in opening, by reason of the 

 upheaving tresses, left vacant spaces to be filled by the invading 

 rocks. At Swift's Creek, and the other places, the strata under 

 such conditions have been deflected from their normal stride some 

 forty-five degrees. 



The metamorphic area having been formed, the plutonic rocks 

 again became irruptive, forming areas around the border of the 

 schists, and also in a less degree within them as I have described. 



At this stage or possibly later occurred the volcanoes which 

 pi'oduced the Snowy River porphyrites and the diabases of 

 Buchan, and these vents to plutonic action apparently died out 

 when in the Middle Devonian period the uppermost of the Buchan 

 tufts and agglomerates and the quartz porphyries of Bindi were 

 submerged and were connected by. passage beds with the purely 

 marine limestones of those places. 



This then as I see it, is the history of that phase of geological 

 histoi'y from the Upper Silurian to the Middle Devonian in which 

 the crystalline schists of Eastern Victoria were formed. It was 

 an age of earth stresses, of putonic action upon the subterranean 

 crust, and of volcanic activity finding a passage to the earth's 

 surface. 



The results of this investigation into the structure and origin 

 of the crystalline schists appear to me to arise naturally out of 

 the observed facts, and to accord in a satisfactory manner with 

 the outcome of the extended and exhaustive investigations of 



