BY THE REV. W. B. CLARKE, M.A., F.G.S., &c. 277 



morphic. We learn, also, in this way, how certain granites 

 themselves, which are really schistose in structure, and might be 

 even termed stratified, have resulted from the transmutation of 

 ordinary schists. 



Such I have described, in one of my reports to the Govern- 

 ment, as having been met with by me in the neighbourhood of 

 the Murrumbidgee River. 



I have already mentioned the alterations which shales and 

 sandstones have undergone in connection with the granite mass 

 of the Sappa Bulgas or Harvey's Range, west of Molong. 



Now, I have ascertained from inquiry and examination of the 

 rocks, that all along the western frontier of New South Wales, 

 as on the Darling River, and between it and the Barcoo, there is 

 an enormous development of silicified and vitrified sandstones. 



As the phenomena extend over so vast an area, it can hardly 

 be attributed to anything short of a normal transmutation ; and, 

 therefore, in all probability ifc may be to the action of granite 

 rather than of any real trappean rocks. There is, I think I may 

 safely say, no range of any considerable elevation or extent in the 

 low region along the Darling, which does not betray the clearest 

 proof of transmutation. And in some parts of the country, far 

 beyond, near the Lower Barcoo (or Cooper's Creek), Mr. A. C. 

 Gregory found the rocks altered in a remarkable degree. 



The late Sir T. L. Mitchell made a similar observation, but 

 he merely mentions the fact without attempting to account 

 for it. Both he and Captain Sturt were struck by the poly- 

 gonal forms and hardened nature of many loose fragments on the 

 summits of the groups of hills, such as D'Urban's, Dunlop's, 

 Greenough's, &c. In the hills which lie along the river 

 channels of the Narran and Bokara, 150 miles further north, 

 pebbles of such transmuted rocks occur in abundance. The 

 collection here present was made from the ridges of that 

 neighbourhood near Curawallinghi, on the Ballandoon River. 

 The conclusion from them must be, that great denudation, of 

 which these are the spoils, has taken place, and that formerly the 

 insulated groups of hills were connected in one grand plateau, 

 the less hardened masses having been removed. 



As we pass onwards to the Balonne and along the Maranoa, 



