THE EUEOPEAN SEAS. 



255 



map which accompanies this volume, the extent of 

 this subsided and submerged tract is indicated 

 by dotted lines ; but, as will be seen, this broad 

 expanse of sea is marked by the emergence of land, 

 at intervals, between the Western Islands of Scot- 

 land and the east coast of Greenland, at Iceland, 

 and by the Orkney, Shetland, and Feroe Archi- 

 pelagos. These islands, which have elevations of 

 from 2000 to nearly 3000 feet above the sea, were 

 the culminating points of this old terrestrial sur- 

 face. Conclusive evidence of the continuity of land 

 connecting these several groups of islands will be 

 found in the common character of their flora, and 

 in the relation of that flora to the Boreal and 

 Alpine plants of the Old and New Worlds. 



A full description of the botany of these North 

 Atlantic groups, and of M. Martin's views respect- 

 ing them, will be found in a former volume* of 

 this series. 



With the exception of this limitation at its 

 northern extremity, the Atlantic is an old area of 

 depression. There was an Atlantic ocean for the 

 nummulitic, cretaceous, and palaeozoic periods, 

 during each of which it had its distinct zones of 

 distribution in latitude, as well as its corresponding 

 provinces of representative forms on its opposite 

 sides. Our present inquiry is, however, relative 

 solely to the growth or formation of that assem- 



* Yegetation of Europe, by Arthur Henfrey, pp. 132- 

 154. 



