i8 .Diorites and Granites of Siviftfs Creek, 



lithological character of the sediments themselves. Such 

 cases occur at the Limestone River, and at Tabberabbera. 

 From this we are justified in concluding that the folding, 

 compression, and denudation of the older palceozic sedi- 

 ments, which constitute the great bulk of the series of 

 which I have spoken, has been the result of successive 

 movements of the earth's crust extending over vast periods 

 of time. 



It may, I think, be provisionally accepted that the great 

 series of slates and sandstones of North Gippsland, in which, 

 to the east of the Mitchell River, are situated most of the 

 gold- workings, is of Lower silurian age;* and it is in this por- 

 tion of the district that Swift's Creek is situated. I speak 

 of this series throughout this paper as Lower silurian, leav- 

 ing to the future the determination of other local exceptions 

 similar to those to which I have alluded. 



At the Upper Dargo River the Lower silurian formations 

 pass within a space of about two miles by the production of 

 mica, and the segregation of silica into mica schist, and by 

 the further accession of felspars into gneiss, and ultimately 

 as the extreme of the series into granite. 



These altered rocks constitute a well-marked series of 

 metam orphic schists. There are no intrusive igneous rocks 

 to which the changes I have noted may be due ; and an 

 examination of the district shows me that these changes 

 have been the result of what has been termed regional, in 

 contradistinction to contact, metam or phism. 



I cannot enter in this paper into a consideration of the 

 regional metamorphic schists of Omeo, and I propose to deal 

 with them at a future time. It will now suffice to point out 

 that, starting from the metamorphic area, the degree of 

 change is found to decrease from some given central point 

 until, as, for instance, at a little beyond Swift's Creek, the 

 schists gradually pass into a series of nearly vertical slates 

 and sandstones similar in general character to those I have 

 spoken of as found at the Upper Dargo River. Thus, south 

 of Swift's Creek the series again assumes at the source of the 

 Nicholson River those characters which I have described as 

 characterising it in the goldfield regions of North Gippsland. 

 The crystalline schists of Omeo are the regionally meta- 

 morphosed representatives of the Lower silurian formations. 



* The only localities where fossiliferous beds have been met with are east 

 of the Snowy Kiver — e.g., Guttarnurra and Deddick.— See Report of Progress 

 of Geological Survey of Victoria, Part III., p. 186. 



