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would be increased when the excentricity reached a maximum, 

 as already fully explained, and may then have caused glaciers to 

 descend into the adjacent sea, carrying those enormous masses 

 of rock which are buried in the Upper Miocene of the Superga 

 in Northern Italy. An earlier epoch of great altitude in the 

 Alps coinciding with the very high excentricity 2,500,000 years 

 ago, may have' caused the local glaciation of the Middle Eocene 

 period w^hen the enormous erratics of the Flysch conglomerate 

 were deposited in the inland seas of Northern Switzerland, the 

 Carpathians, and the Apennines. This is quite in harmony with 

 the indications of an uninterrupted warm climate and rich 

 vegetation during the very same period in the adjacent low 

 countries, just as we find at the present da}^ in New Zealand a 

 delightful climate and a rich vegetation of Metrosideros, fuchsias 

 and tree-ferns on the very borders of huge glaciers, descending 

 to within 700 feet of the sea-level. It is not pretended that 

 these estimates of geological time have any more value than 

 probable guesses ; but it is certainly a curious coincidence that 

 two remarkable periods of high excentricity should have occurred, 

 at such periods and at such intervals apart, as very well accord 

 with the comparative remoteness of the tw^o deposits in which 

 undoubted signs of ice-action have been found, and that both 

 these are localised in the vicinity of mountains which are known 

 to have acquired a considerable elevation at about the same 

 period of time. 



In the tenth edition of the Princiides of Geology, Sir Charles 

 Lyell, taking the amount of change in the species of mollusca 

 as a guide, estimated the time elapsed since the commencement 

 of the Miocene as one-third that of the whole Tertiary epoch, 

 and the latter at one-fourth that of geological time since the 

 Cambrian period. Professor Dana, on the other hand, estimates 

 the Tertiary as only one-fifteenth of the Mesozoic and Palseozoic 

 combined. On the estimate above given, founded on the dates 

 of phases of high excentricity, we shall arrive at about four 

 million years for the Tertiary epoch, and sixteen million years for 

 the time elapsed since the Cambrian, according to Lyell, or sixty 

 millions according to Dana. The estimate arrived at from the 

 rate of denudation and deposition (twenty-eight million years) 



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