HuTTON. — On the Thames Gold Fields. 277 



formation; while (at page 91) he says that at Driving Creek "no proper 

 volcanic rocks have ever been met with in the underground workings when 

 they have proved auriferous." Again, this " grey tufaceous sandstone" of 

 Tokatea is called by Dr. Hector in another place (p. 96) "greenstone tuff," 

 while Mr. Davis (p. 97) calls the same rock "trachytic tufa." Again, at 

 Tapu, what Dr. Hector calls (p. 98) " greenstone porphyry," Mr. Davis calls 

 (p. 99) " older trachytic breccia." Dr. Hector, also, although he acknowledges 

 (Trans. N.Z. Inst., II., 367) that the bed rock of the auriferous lodes is the 

 same both at Coromandel and the Thames — and therefore, according to him, 

 "greenstone tuff" or "green tufaceous sandstone" — calls (Trans. N.Z. Inst., 

 I., 48) the bed rock from the Golden Crown Claim a "felstone." It seems, 

 therefore, to me that Dr. Hector has entirely failed to distinguish by litho- 

 logical characters the difference between his two formations ; and I may remark 

 that no greenstone tuff, nor any other basic tufaceous rock, has ever yet been 

 brought from the Thames, and that the term " greenstone tuff" is altogether 

 a misnomer. Of course all agglomerates formed by the latest eruptions would 

 be considered by Dr. Hector as belonging to his younger formation, and it is 

 quite true that they never contain gold ; but I shall presently show how it is 

 that these superficial accumulations could not be expected to contain gold in 

 any quantity, and that they afford no proof of two formations. 



Great stress has also been laid by Dr. Hector on the supposed similarity of 

 the gold-bearing rocks of the Thames with those of Waimungaroa, Batten 

 River, Cape Terawiti (Prog. Report, 1866-67, p. 32), Dun Mountain (Trans. 

 N.Z. Inst., II., p. 365 ; and III., p. 288), and of Gympie, in Queensland 

 (Trans. N.Z. Inst., II., pp. 366 and 399; also Museum Report, 1870, p. 4). 

 Putting aside the question whether identity of age can in any way be proved 

 by the identity of the rocks from such distant localities,* I must remark that 

 having examined rocks from the Dun Mountain, Cape Terawiti, and Gympie, 

 I can find but a very superficial resemblance between some of them and some 

 of the melaphyres of the Thames, which occur only in dykes, and never contain 

 gold veins. The analyses of the rocks from Gympie — which are from the 

 identical specimens that Dr. Hector says he cannot distinguish from Thames 

 rocks — show that there is a wide difference between them, while the analyses 

 of the Dun Mountain rocks (Lab. Report, 1871, p. 17) show a still greater 

 divergence from those of the Thames ; the only one that nearly approaches in 

 composition to the Thames auriferous rock being No. 9 — " a fine-grained 

 argillaceous slate, with slaty cleavage." In fact, the Gymj^ie and Dun 

 Mountain volcanic rocks are true greenstone tuffs, while the Thames rock is a 

 trachyte of a totally different character to the others. 



* The Gympie rocks have been shown by Messrs. Daintree and Etheridge to be of 

 Devonian age, while the occurrence of Inoceramus in the Dun Mountain shows that 

 those rocks cannot be older than the Lias. 



