350 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1908. 



with no evidence of any refrigeration of Europe at the date of the 

 Gondwana-Land ghiciation. 



Again, the Upper Paleozoic glacial deposits of southeastern Aus- 

 tralia do not appear to have been synchronous in all the localities. 

 The glacial deposits on the northern coast of Tasmania have been 

 shown by Kitson " to be of the age of the Mersey Coal Measures of 

 Tasmania, which may be correlated with the Lower or Greta Coal 

 Measures of New South Wales. The Victorian glacial deposits are 

 probably on approximately the same horizon, which agrees with some 

 of those of New South Wales. But, according to David,^ there were 

 glacial deposits in New South Wales at the following different 

 stages in the Permo-Carbonif erous : 



Branxton Glacial beds in the Upper Marine series. 



Greta Coal Measures. 



Shales with occasional erratics in the Lower Marine series. 



Lochinvar Glacial Beds at the base of the Lower Marine series. 



Again, whatever view may be held on the conti*oversy as to the 

 occurrence of warm interglacial periods during the Pleistocene gla- 

 ciation of Europe, it will be generally admitted that considerable 

 oscillations occurred in the extent of ice. Thus the evidence in the 

 British Isles strongly supports the view that after the maximum 

 glaciation there was a reduction in the extent of the ice, and then, 

 after some interval, a fresh advance of valley glaciers. And such 

 interludes, of which in the British Isles there may have been more 

 than one, Avould appear to require considerable variations in the 

 amount of carbonic acid in the atmosphere, repeated within a short 

 period of time. 



Weighty evidence is also given against Arrhenius's theory by the 

 dates of the glaciations, as they do not correspond with those at which 

 variations in the carbonic-acid contents of the atmosphere would be 

 most probable. Widespread volcanic eruptions offer the simplest 

 explanation of the addition of large volumes of carbonic acid to the 

 atmosphere ; but periods of intense volcanic activity do not appear to 

 have been always followed by glacial epochs. 



The great volcanic periods — the Devonian, the Permian, the Upper 

 Cretaceous, the Eocene, and the Oligocene — were not followed by 

 marked developments of glaciers. The one coincidence is in the case 

 of the Upper Carboniferous or Permian glaciation of Gondwana 

 Land. The Pleistocene glaciation followed a period in which vol- 

 canic action was powerful, but was probably less than at other periods 

 not followed by glacial advance. 



<^A. E. Kitson, "On the occurrence of glacial beds at Wynyard, near Table 

 Cape, Tasmania," Proc. Roy. Soc. Victoria, new ser., Vol. XV, 1902, p. 34. 



'''T. W. E. David, " Discovei'y of glaciated boulders at base of Penno- 

 Carboniferous system, Lochinvar, New South Wales," Journ. Roy. Soc. New 

 South Wales, Vol. XXXIII, 1S!)9, pp. 154-159. 



