168 THE OCEAN RIVER 



land before finding floe ice. Fifty years later a Norseman 

 called Ingolf, pioneering at Reykjavik, spoke of the land be- 

 ing wooded from the mountains to the shores, and other early 

 settlers spoke of tillage and a harvest of small grains. Annual 

 drift ice, so common in our day around Iceland, was not 

 mentioned in the early chronicles until 1200 a.d. The weather 

 in medieval Europe for the most part was stormy and cold. 

 This change caused the Norse to shift their course to the 

 southward when they sailed to their Greenland colony. It also 

 brought down the icecap and with it the Eskimo, who finished 

 off the Greenland colony about fourteen hundred. Many 

 catastrophes in Europe due to terrible storms and floods fall 

 in these years. In the thirteenth century 80,000 people were 

 drowned in Holland, and by the fourteenth century the in- 

 closed Lacus Fleve — renamed the Zuider Zee — was open 

 to the waters of the North Sea. 



Various explanations have been offered for this change in 

 the steady nature of the weather of our northern hemisphere. 

 Huntington lays it to phenomenal sun-spot activity, especially 

 in the thirteenth century, when solar radiation was supposed to 

 have been exceptional. O. Pettersson has made a detailed study 

 of cold Atlantic underwater waves, which oscillate between 

 layers of water with marked density differences just as they 

 do between water and air; he says that they were at a maxi- 

 mum in the fifteenth century. These thrusts of cold Atlantic 

 waters into the Baltic herald a greater turbulence and mixing 

 of cold and warm waters and hence an increased convection 

 and storminess. They also pump into the Baltic with the 

 colder waters great schools of herring, which normally do 

 not penetrate beyond the Skagerrak off Denmark. 



The object in tracing the history of these phenomena is 

 to demonstrate how continuously, since records have been 

 known, the currents of the sea and the weather above them 

 have fluctuated through the years, and have thus changed the 

 history of the welfare and expansion of civilized man in 



