198 DISCUSSIONS IN CLIMATOLOGY. 



respect to the Arctic regions, due attention has not 

 been bestowed on floating ice and ocean currents, par- 

 ticularly the Gulf Stream, as transporting agents. Of 

 the multitude of Scandinavian plants carried down by 

 streams, land-slips, and other causes into the sea, some 

 could not fail to find their way to Greenland, Iceland, 

 and the Faroes. The Gulf Stream, of course, would 

 not directly convey the plants from Scandinavia to 

 Iceland and the Faroe Islands, but the return currents 

 might. The water flowing out of Arctic seas must 

 always equal in amount that flowing into them. The 

 wide -extending Gulf Stream, to the north-west of 

 Scandinavia, is met by an immense flow of polar 

 water from the north, which polar current, on meeting 

 the warm stream, passes underneath it, and continues 

 its course southwards as an undercurrent.* Were 

 the volume of the Gulf Stream considerably reduced, 

 a thing which it evidently was during at least a part 

 of the postglacial period, the polar current would not, 

 as now, pass under the stream, but would pursue its 

 course as a surface current outside of it in the direction 

 of Iceland and the Faroes. This current would doubt- 

 less, now and again, carry to these places materials 

 derived from the Gulf Stream. There can be no 

 absolute separation between the Gulf Stream and the 

 return currents. The water flowing northward warm 

 ultimately returns cold. The two sets of currents are 

 but parts of one general system of circulation. 



As for Greenland, we have no grounds for concluding 

 that the waters of the Gulf Stream do not actually 

 reach its eastern shores, although by that time they 

 may have become part of the cold return current. It 

 is certainly not unlikely that, at a period when the 

 Arctic seas were less encumbered by ice than at 



* ' Climate and Time,' p. 219. 



