8o THE HISTORY OF THE NORTH ATLANTIC 



Atlantic life not equalled in later times,^ and which speaks of 

 true contemporaneity rather than of what has been termed 

 homotaxis or mere likeness of orders. 



We may pause here for a moment to notice some of the 

 effects of Atlantic growth on modern geography. It has 

 given us rugged and broken shores, composed of old rocks 

 in the north, and newer formations and softer features to- 

 ward the south. It has given us marginal mountain ridges 

 and internal plateaus on both sides of the sea. It has pro- 

 duced certain curious and by no means accidental corre- 

 spondences of the eastern and western sides. Thus the solid 

 basis on which the British Islands stand may be compared 

 with Newfoundland and Labrador, the English Channel with 

 the Gulf of St. Lawrence, the Bay of Biscay with the Bay of 

 Maine, Spain with the projection of the American land at 

 Cape Hatteras, the Mediterranean with the Gulf of Mexico. 

 The special conditions of deposition and plication necessary 

 to these results, and their bearing on the character and pro- 

 ductions of the Atlantic basin, would require a volume for 

 their detailed elucidation. 



Thus far our discussion has been limited almost entirely to 

 physical causes and effects. If we now turn to the life 

 history of the Atlantic, we are met at the threshold with the 

 question of climate, not as a thing fixed and immutable, but 

 as changing from age to age in harmony with geographical 

 mutations, and producing long cosmic summers and winters of 

 alternate warmth and refrigeration. 



We can scarcely doubt that the close connection of the 

 Atlantic and Arctic oceans is one factor in those remarkable 

 vicissitudes of climate experienced by the former, and in 

 which the Pacific area has also shared in connection with the 



^ Daintree and Etheridge, " Queensland Geology, "/<?//;-««/ Geological 

 Society, August, 1872 ; R. Etheridge, Junior, " Australian Fossils," Trans. 

 Phys. Soc, Ed in., 1880. 



