BY LEO A COTTON. 



739 



distributed on the western border of tlie countr}' between New 

 England and the interior.'" 



Unfortunately I have not seen the occurrence thus described 

 by Mr. Gower, though I am well acquainted with Newstead. 

 There can be no doubt, however, that the occurrence, so far from 

 ))eing typical of the sedimentary formations in this district, is 

 most exceptional. The nearest related rocks are those described 

 by Professor David from Vegetable Creek. In these he found 

 rather obscure fossil remains, and has concluded that the series 

 is Upper Silurian or Siluro-Devonian. 



Another point in favour of the geological antiquity of the rocks 

 is the occurrence in them of ore-bodies other than tin. At " The 

 Brothers," near Newstead, a small reef was opened up for silver 

 and lead, and similar bodies of galena and arseno-pyrite are 

 common in the slates about eight miles south of Tingha, Hence 

 lithological characters favour a correlation with Ordovician and 

 Silurian rocks, and the system may provisionally be classed as 

 Silurian. 



The age of the granites must, on this basis of classification, be 

 regarded as Post-Silurian, as evidence of their intrusion into tlie 

 slates is abundant. Professor David has classed the intrusive 

 tin-bearing granite at Emmaville as Permian, for the following 

 reasons. (1) It maybe correlated with the granite which has 

 intruded the Permo-Carboniferous rocks at Ashford. (2) No 

 granites in New South Wales have appreciably disturbed Triassic 

 rocks. 



Another fact in confirmation of this proposed age for the 

 granites, is the statement by the Rev. W. B. Clarke^ that 

 *' geologists at Home have settled it that the stanniferous granites 

 are Palaeozoic, Pre-Permian, and Post-Silurian." 



Again Mr. David Forbesf said at the Geological Society's 



meeting in December, 1871, that he had received specimens of 



the granite from the New South Wales tin-region, in the yeat- 



1859, and that he found them to be " perfectly identical with the 



stanniferous granites of Cornwall, Spain, Portugal, Bolivia, Peru, 



and Malacca." 



*Mines and Mineral Districts of New South Wales, 1875, p. 86. 

 flhid. 



