514 



REVIEWS 



emphasized are that they range over almost the whole of known geological 

 history (Proterozoic to Pleistocene) and that the intervals between them 

 are much greater than the glacial periods themselves. There follows this 

 table a summary of what is now known of the geologic climates of Ant- 

 arctica (p. 419) the gist of which is here given because of its special interest. 



TABLE OF GLACTAI. PERIODS 



Main Proved Glacial 

 Periods 



Local Glaciation 



Countries Where 

 Developed 



Remarks 



I. Huronian. 



2. Proterozoic 



3, Proterozoic or 

 Lower Cambrian. 



4. Devonian 



5. Permo-Carbon- 

 iferous 



Cretaceous 



7. Pleistocene 



Canada 



India 1 

 Africa [ 

 Norway] 



China 

 Australia 



South Africa 



Australia 

 S. Europe 

 Brazil 

 Africa 

 India 



World-wide 



Pre-glacial surface an undtilating 

 surface of low relief. 



Possibly two separate glacial 



periods combined. 

 In Norway probably low land as 



pre-glacial surface. 



fMiddle latitudes N. and S. of 

 Equator. Australian geolo- 

 gists claim this Ice age in 

 Australia as Lower Cambrian; 

 United States geologists insist 

 that here also it is Proterozoic* 



Middle to low latitudes. Sea- 

 sonal climate in N. and S. 

 Marked inter-glacial periods. 

 Developed on plateaux of low 

 relief and mountains not par- 

 ticularly glaciated. 



fParticularly effective in high 

 latitudes. 



Several inter-glacial periods. 

 Chiefly developed on high 

 plateaux. The only glaciation 

 yet proved in Antarctica. Ap- 

 parently began there in 

 Eocene or Oligocene times, and 

 has been interrupted by inter- 

 glacial periods. 



* Information has recently been received from Australia to the effect that Professor David, who has 

 re-examined the exposures, now agrees with the United States geologists in their view of the Proterozoic 

 age of these deposits. 



Respecting the climates of the pre-Cambrian ages little evidence has 

 been found in Antarctica. The presence of limestone and graphite seems 

 to imply at least moderate warmth at the specific stages they represent, 



