• GEOLOGY OF TASMAJ^IA. 59 



knowledge of the general geology of the Island. Mr. W. F. 

 Petterd has contributed his " Catalogue of Minerals of Tas- 

 mania," and several papers on the eruptive rocks. Other 

 workers, Professors David, Tate, Krause, Hogg, Feistmantel, 

 Mr. R. Etheridge, Jvm., Mr. J. Dennant. have added the re- 

 sults of their researches, while the names of authors of 

 papers read before the Royal Society of Tasmania (Messrs. 

 W. F. Ward, Alex. Morton, Danvers Power, T. B. Moore, 

 Graham Officer, &c.) suffice to show that this Society has 

 had an honourable share in the construction of the literature 

 of the subject. 



Mr. R. M. Johnston., the doyen of Tasmanian geologists, 

 has worked out thoroughly the stratigraphy of the Tertiary, 

 Mesozoic, and Upper Palaeozoic systems, and successive 

 Government Geologists have contributed to our knowledge 

 of detached areas in different parts of the Island ; but the 

 lower Palaeozoics still require much study before they can 

 be properly defined. In this sketch, the main develop- 

 ments of each syste^m, as far as at present known, will be 

 briefly referred to. 



Fre-Camhrian. 



The massive quartzites at Port Davey are usually referred 

 tO' this age, but their stratigraphical relations need working 

 out. The mica-schists and gneiss-like rocks at the Dove 

 River, and the hornblende zircon-gneiss of the Upper Forth, 

 are also possible members. In the North-West, the horn- 

 blende and talc schists, with associated dolomitic limestone 

 in the Rocky River district, enclosing deposits of pyrrhotite 

 and copper pyrites, need investigation. These rocks are 

 well seen at the Rocky River Mine, and at the Rio Tinto, 

 further north, on the same strike. The hornblende schist 

 runs through to the junction of the Nine-mile Creek with 

 the Whyte River. 



Cambrian. 



The only strata which can be definitely referred to the 

 Cambrian system are the friable yellow sandstones at Caro- 

 line Creek, between Railton and Latrobe. These have a 

 strike (E. 60° S.) different from the prevailing direction of 

 the Silurian strata of the Island, and contain Dikelocefhalus 

 tasmanicus (R. Eth., Jun.), Conocephalites stephensi {R. 

 Eth., Jun.), Asajphus sp., Scolithus tasmanicus (B. M. John- 

 ston), Leptaena. These are the most ancient fossils yet 

 found in oiir rocks. The elucidation of the relations of 

 these strata with the adjacent schists and limestones is much 

 needed. 



