282 REPORTS ON THE STATE OF SCIENCE. — 1915. 



ally with the correlation, suggests a few additions, and claims that 

 correlation by evidence of a climatic revolution is probably safer than 

 by evidence of fossils where widely separated areas ai«e concerned. 

 Professor Skeats accepts Professor David's and Professor Woolnough's 

 additions and modifications to the correlation with certain minor reser- 

 vations as to the probable horizon of the lower part of the Maitai series 

 in New Zealand, and of the upper part of the Bacchus Marsh series 

 as expressed in Professor David's table. He agrees with Professor 

 Woolnough's remarks about correlation by evidence of a climatic revo- 

 lution, provided that in the case of the formation of a Glacial series 

 no marked inequalities of land level, or of the relations of land and sea, 

 or evidence of slow migration of the areas of maximum glaciation, are 

 involved. Where palseontological and lithological evidence of Glacial 

 deposits are combined, the probabilities of the series in different areas 

 being contemporaneous are much increased. 



6. Are relations between Devonian and Carboniferous rocks in the 

 Southern Hemisphere everywhere conformable ? No replies have been 

 received. Professor Skeats maintains the existence of a conformable 

 sequence in Victoria and in South Africa, but does not know the rela- 

 tions in other areas. 



7. In respect to the question as to the areas of accordance and of 

 discordance between Carboniferous and Permo-Carboniferous rocks, 

 Professor David points to discordance at Ashford and Pokolbin in New 

 South Wales, and at the Nandewar Eanges (between the Newcastle 

 series and the Carboniferous) ; to accordance at Seaham and Burindi 

 in New South Wales. Professor Woolnough refers to accordance in 

 the central coastal areas of New South Wales, while Professor Skeats 

 refers to accordance in the south of South Africa and discordance in 

 the northern parts of South Africa and in parts of New South Wales. 

 In Victoria the two series do not come in contact with each other 

 60 far as is known. 



8. In respect to the question as to the upper limit of the Permo- 

 Carboniferous and its separation, if any, from the Permian, Professor 

 David and Professor Skeats agree that the upper limit is the upper hmit 

 of the Glossopteris flora, ^ while Professor Skeats claims that since 

 rocks with the Glossopteris flora usually pass gradually into Mesozoic 

 rocks, the Permo-Carboniferous series must be taken to include the 

 whole of the Permian series. 



Note. — While Mr. W. S. Dun has not directly contributed to this 

 discussion, it is understood that he consulted with Professor David and 

 agrees generally with his conclusions. 



3 This view ia expressed with reference to the Southern Hemisphere only, since 

 Glossopteris has been recorded from the Rhaetic series in Tonkin, &)uth China, and 

 Mexico. 



