ANTARCTIC ADVENTURE AND RESEARCH 



sentially of blocks of the earth's crust bounded by 

 definite north-south fault-scarps. The eruptive rocks 

 are like those of South Australia. The fossils are also 

 similar. In West Antarctica (Graham Land, etc.) 

 we seem to see a continuation of the South American 

 Andes. These are folded mountains occurring often 

 in arcs, one of which appears to link Chile with Ant- 

 arctica by way of the drowned islands of South 

 Georgia, South Orkneys, etc. Here, moreover, the 

 eruptive rocks belong to a dififerent province from those 

 of Victoria Land and consist of a calc-alkaline series 

 of granodiorites and basalts akin to those of the 

 Andes. Probably the greatest unsolved problem as re- 

 gards the earth's structure is the relation of these two 

 regions to each other. Are there tivo Antarctic con- 

 tinents, separated by straits or archipelagic areas? Or 

 do the Antarctic Andes die away against an infinitely 

 larger plateau of the Australian type? The latter 

 seems probable, and if Antarctica as a whole is 

 covered with an ice carapace, we shall probably wait 

 many a long year for a satisfactory answer. 



Finally the whole problem of the general evolution 

 of the earth in geological times is only to be solved by 

 frequent references to polar evidence. Recent research 

 has shown that in the five hundred million years of 

 which geology gives us the record the earth was for 

 most of the time characterized by a more uniform en- 

 vironment both of topography and climate than in the 

 present epoch. Plant and animal life was also more 

 cosmopolitan than to-day. There was probably much 

 less differentiation of those climatic zones ( frigid, tem- 



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