THE ARRIVAL OF MAN IN EUROPE 



are clearly bound to look to the latest rather 

 than to any earlier manifestation of those causes, 

 in order to account for that glacial period the 

 effects of which are still visible all around us. 

 Accordingly, among the foremost geologists 

 who have adopted Mr. Croll's conclusions, 

 there has been a general agreement that the 

 period of high eccentricity which began 240,000 

 years ago and ended 80,000 years ago must 

 have been coincident with the great period of 

 glaciation which occurred during the Pleisto- 

 cene age in Europe and America. 



The most serious objection that has been 

 urged against Mr. Croll's theory is that it 

 seems to require us to suppose that there have 

 been recurrent glacial epochs, at irregular in- 

 tervals, during the whole past duration of the 

 earth's history. And in particular it would 

 seem to be implied that there must have been 

 a great glacial period from 880,000 to 700,000 

 years ago, and another one from 2,650,000 to 

 2,450,000 years ago, both of these dates being 

 long subsequent to the beginning of the Ter- 

 tiary period. Mr. Croll has sought to meet 

 these objections by showing that such must 

 really have been the case. He alleges evidence 

 of glaciation in every one of the geological pe- 

 riods back to the Cambrian, with the single ex- 

 ception of the Triassic. And he argues, in par- 

 ticular, that the epoch of high eccentricity which 

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