I20 SEA AND LAND 



over and under each other, thus thickening the floes in a very 

 rapid manner. As soon as these cakes of ice come to rest 

 in their new position, they are soklered together so that the 

 floe is a solid mass wliich ma)' drift away for great cHstances 

 in the control of the winds or the shallow currents of the sea. 

 So massive are they, indeed, and so vast in number and area, 

 that but for the nature of the current systems of the North 

 Atlantic, they might greatly embarrass the main line of ship 

 travel between the northern parts of Europe and those of the 

 northern United States and Canada; but the direction of 

 their southward migration is, as we shall now note, greatly 

 affected by the ocean currents. 



All the superficial parts of the western Atlantic, except the 

 portion of its area next the coast of America, are pervaded 

 by a slow movement which sets the water toward the Poles. 

 This current is due to the Gulf Stream, which, emerging from 

 the troj^ics as a deep, narrow, swift-moving tide, skirts the 

 southern coast of the United States, gradually widens like an 

 opened fan, diminishing in depth and losing its velocity as it 

 comes toward the Arctic Circle. Although the speed of its 

 northward going is here slight, it has sufficient energy to push 

 l)ack the floe-ice which may be driven southwardly by the 

 winds, and thus limit its excursions to the American shore. 

 Setting out into the Atlantic from Davis Strait, there is, how- 

 ever, a strong stream of .Arctic water, which in part slips 

 under the Gulf Stream tide, and in part flows on the surface 

 of the sea next the Labrador coast. In this southward-setting 

 current the floe-ice drifts with a speed of about a mile an hour 

 down the American shore until it attains the mouth of the St. 

 Lawrence. The Labrador current, as this southward-movincr 

 water is called, would, Init for certain accidents of geography. 



