336 C. A, SUSSMILCH AND T. W. E. DAVID. 



first cause of the glaciation were certaiuly an important 

 contributing factor; (b) The unprecedented development of 

 volcanic dust, produced in Kuttung time may also, on 

 Humphreys' hypothesis, 1 have contributed to the glaciation 

 by intercepting the sun's heat above the surface of the 

 atmospheric stratosphere. 



14. By giving so wide a choice of dates for the "Permo- 

 Oarboniferous " glacial deposits throughout the world the 

 recent evidence from Australia collected by my co-author 

 obviously adds to the complexity of the task of correlating 

 these beds. At the same time it furnishes a truer view of 

 this vast and fascinating problem, and should be a warning 

 against any attempt to press on slender evidence for 

 absolute contemporaneity in these Late Palseozic glacial 

 deposits, some of which may be separated from one another 

 by a considerable time interval, an interval amounting 

 probably to many millions of years, 



More evidence is much needed, not only from Australia, 

 but from every part of the world, where "Permo-Carboni- 

 ferous" strata have been identified. Much may be ex- 

 pected from a detailed examination of the extensive 

 Permian etc. deposits of Alaska. 



Acknowledgements. — The author is specially indebted to 

 Mr. C. A. Sussmilch for guidance in the field geology of the 

 Kuttung series. Professor W. N. Benson has been most 

 generous in supplying information about the equivalents of 

 the Kuttung series to the west of the area from Tam worth 

 to Bingara. To Mr. Ludwig Glauert of the Geol. Survey 

 of West Australia is chiefly due the census in this paper of 

 the Irwin River fossils. Mr. W. S. Dun has helped through- 

 out with palseontological notes and references. Mr. W. R. 



1 W. J. Humphreys, Volcanic Dust and other Factors in the Production 

 of Climatic Changes, and their possible Eolation to Ice Ages. Bull, of the 

 Mount Weather Observatory, Vol. vi, part 1, Aug. 20, 1913, pp. 1 - 26. 



