CARBONIFEROUS ROCKS OF THE SOUTHERN HEMISPHERE. 279 



VIII. 



Discussion by the Hon. Secretary, Professor Skeats, of the 

 ■ points raised by him, after reading the replies of Professor David, 

 Professor Woolnough, and Mr. Howchin. 



1. A single common name with local names used in a purely geo- 

 graphical sense is advisable. For example, in Victoria, among rocks 

 grouped as Permo-Carboniferous, are the Bacchus Marsh series, the 

 Knowsley series, the Loddon Valley series, the Coleraine series, &c. 

 Only at Bacchus Marsh is there definite palasontological and strati- 

 graphical evidence of the age of the rocks, and it therefore is probably 

 inadvisable to include them all under one local name and thereby tacitly 

 assert contemporaneity between them, although all are probably Permo- 

 Carboniferous. Professor David is, I think, incorrect in claiming that 

 the Bowen series of Queensland includes more than the Bacchus Marsh 

 series. The latter series appears to range continuously and conformably 

 from the basal Glacial series through Gangamopferis-hearing sand- 

 stones up to beds, probablv of Triassic affinities, containing Schizoneura 

 and Taniopteris Sweeti (McCoy). 



2. The term Permo-Carboniferous is already firmly established, and 

 I know no good reasons for changing it, especially as Carboniferous 

 marine types in "Western Ausitralia and Carboniferous land plants 

 (Aneimites or Rhacopteris) at Seaham, in New South Wales, are 

 included in the series which otherwise, on the bulk of the palseonto- 

 logical evidence, might apparently have been called Permian. 



3. It seems inadvisable to apply a single local name to all the 

 Australian occuri-ences of presumably Permo-Carboniferous rocks. 

 Hunterian is a suitable name for the very complete marine and lacus- 

 trine development in New South Wales. The Victorian sequence is, 

 however, very distinct, being at Bacchus Marsh mainly fluvio-glacial, 

 with several included tillites derived from land ice, while in other 

 Victorian localities the tillite is alone represented or is predominant. 

 In South Australia the Tnman series, as it might suitably be called, 

 consists largely of tillite. As there are two or more glacial episodes 

 known in New South Wales and Vfctoria, and as in South Australia we 

 have no definite stratigraphical and palaeont-ological evidence of the age 

 of the tillite, the giving of a single local name to the tillite (comparable 

 with the term Dwyka, in South Africa) seems premature. 



4. It cannot yet be proved that the prominent Glacial horizon at 

 the base of the series is everywhere in Australia contemporaneous. In 

 New South Wales, Victoria, Queensland, and Western Australia Glacial 

 conditions recur higher in the series. In South Australia, as has been 

 stated, no definite evidence of the age of the Glacial series has been 

 obtained. _ Nevertheless, on the grounds put forward by Mr. Howchin, 

 the prominent Glacial till is probably everywhere on approximately 

 the same horizon. 



5. It is believed that the correlation suggested (by E. W. Skeats) 

 broadly expresses the facts of the relationships of the rocks considered 



