1889.] THE DISPLACEMENT OE BEACH-LINES. 91 



tracts, along- the shores of the Arctic sea, from Greenland and 

 Smith's Sound to the Behring Strait, and through Labrador 

 and Canada down to the northern United States. The highesl 

 marine traces, up to 4—500 metres and even more, occur in the 

 far North. All these regions were therefore, formerly, much 

 less elevated above the sea than now. 



And around the Behring Sea marine Tertiary formations are 

 not rare, showing that the region of Alaska, in Tertiary times, 

 lay perhaps as much as 470 metres lower in relation to the sea than 

 now. 1 It is doubtful whether a similar submergence took place 

 at the Behring Strait, where Tertiary beds are wanting. But it 

 is at least possible, that such was the case. On the Asiatic 

 side the rocks are syenitic, on the American there are ijiiartzites 

 and hard nonfossiliferous slates „with lavas and basalts of late 

 origin". 



During the great Oligocene transgression, according to 

 Nrmntuir and Km*** the Polar sea. probably communicated with 

 the North Sea through Siberia and Northern Germany, which 

 were, at that time, to a very great extent overflowed. 



In comparing the Tertiary mammalian faunas of North 

 America and Eurasia 3 we find, that during the Lower Eocene epoch 

 a considerable number of mammalian types were common to 

 the Nearctic and Palaearctic provinces, showing thai a land con- 

 nection existed, somewhere, at that epoch, between the two con- 

 tinents. And the mammalian faunas of the Middle Eocene epoch 

 tend to show, that at this epoch the connection still lasted But 

 about the Upper Eocene and the Lower and Middle Oligocene epochs, 

 however, a complete diversity is found between the respective 

 mammalian faunas, showing that at those epochs the continents 

 We re not continuous, and that the Polar ocean communicated more 

 fre ely then with warmer seas. From those times we might 

 Possibly date the rich arctic Tertiary flora. But in the Upper 

 "gocene and until the close of the Tertiary period we again find 



a IT" IL DaU ia Amer - Journ - of Sci - Ser - 3 y ° l - 24 (1882) p ' 68 



~ *'->t»iw,r Erdgeach. II p. 491. Sues* Antl. d. Erde II p. 690. 

 Xeumayr Erdgesch. II p. 548. 



