256 



GULF STEEAM. 



blage of marine animals which constitutes our 



existing Atlantic fauna: 



There are certain complex phenomena so imme- 

 diately dependent on the physical arrangements of 

 the earth's surface, that by assuming any definite 

 changes in the conditions, it may safely be inferred 

 what the results would be ; thus the closing of the 

 North Atlantic, in the quarter which has been 

 indicated above, must have had precisely the same 

 influence for that period that it would have now, 

 should it be again closed. 



So long as the Atlantic Ocean has had its exist- 

 ence, and reached from southern and equatorial 

 regions as high as into 60° north latitude, so long 

 must the equatorial current of heated waters have 

 moved from east to west, have been deflected from 

 the American coasts, and again made to cross the 

 Atlantic. When the action of disturbing forces is 

 now temporarily suspended, this current is found 

 setting in upon some part of the western coast of 

 Europe : such, however, is not its ordinary course. 

 It will be seen, by reference to the map, that this 

 broad ocean-river, our " gulf stream," after having 

 flowed for a space of 50° from west to east, is 

 suddenly turned due south in longitude 30° west, 

 and becomes split up into minor currents and 

 eddies. 



This change in direction is due to the prevailing 

 set of the Arctic currents. These are indicated in 

 our map by arrows, which, it will be seen, point 



