Earth' ] s Superficial Temperature. 25 



the west ; and there seems reason to believe that the subsidence may 

 possibly have attained to a considerably greater amount. Now it is 

 manifest that the Gulf Stream is reflected in a north-easterly direc- 

 tion across the Atlantic, by the continent of North America, which 

 arrests the north-westerly course by which the current reaches the 

 Gulf of Mexico. But when that continent was submerged, as above 

 supposed, the current would necessarily continue its north-westerly 

 course, and probably along the foot of the Rocky Mountains directly 

 into the Arctic Sea. This is the manner in which I conceive the 

 Gulf Stream to have been diverted from the shores of western 

 Europe. This diversion of the current is not to be regarded as a 

 mere hypothesis adopted to account for any particular fact, but as 

 a necessary consequence of that submergence of the North American 

 continent. 



Again, if this enormous current discharged itself into the Arctic 

 Sea, it would seem extremely improbable that it should not give 

 rise to some great determinate counter- current out of that sea. Now 

 it appears highly probable that a considerable tract of land must 

 have existed at the period of which we are speaking in the present 

 region of north-eastern America and Greenland. If this were the 

 case, the only practicable outlet for a great current from the Arctic 

 Sea would be across the submerged portion of northern Europe, or 

 along the present North Sea, between Greenland and Norway ; for 

 the passage through Behring's Straits, even with a considerable 

 subsidence of the land on either side, would be neither sufficiently 

 wide nor deep to form a considerable outlet. Under such circum- 

 stances, it would scarcely seem more necessary that the Gulf Stream 

 should hold its original north-westerly course over the submerged 

 continent of America, than that it should complete its circuit by 

 passing through the Arctic Sea, and returning to the Atlantic 

 across the submerged land of Europe, as it now completes a more 

 circumscribed circuit by being constrained to pass along the northern 

 portion of the Atlantic itself. 



The effect of this diversion of the Gulf Stream from its present 

 course, would not be less remarkable in elevating the temperature 

 of the northern shores of America and Asia, than in reducing that 

 of western Europe. I have shown that the mean annual tempe- 

 rature of Iceland is increased 18° or 20° F., and the January tem- 

 perature 34°, by the influence of this important current. Now 

 the distance from the Gulf of Mexico to Behring's Straits is very 

 little greater than the distance between that gulf and Iceland, and 

 the passage of the stream along the flanks of the Rocky Moun- 

 tains would be more direct, and probably less impeded by counter- 

 currents than it is at present in its transatlantic course. There 

 can be no reasonable doubt, therefore, of its raising the temperature 

 of the north-western coasfof America, from the Mackenzie River 

 to Behring's Straits, by an amount at least equal to that by which 



