176 Woeikof — CrolVs Hypotheses of Geological Climates. 



able to glaciation. Such is the condition of many seas of the 

 northern hemisphere, as the Arctic ocean north of Siberia, the 

 Kara sea, the bays and inlets north of the North American con- 

 tinent, the sea of Okhotsk, etc., which are covered with ice dur- 

 ing many months. These conditions are favorable to cold of 

 many months duration, but not to a large snowfall and the 

 resulting glaciation. The observations made at many points off 

 the coasts of Siberia and the North American archipelago have 

 shown that the snowfall is exceedingly light. The seas between 

 45°-70° of southern latitude are deep and not surrounded by 

 land, and thus by far not so ice-bound, both on account of the 

 absence of very low temperatures favorable to the formation of 

 ice, and of the rupture of the ice, when formed, by winds and 

 currents. Such seas as these are very favorable to snowfall 

 and glaciation on land, since, even in mid-winter, there is a 

 great extent of water which evaporates freely. The only parts 

 of the northern hemisphere where glaciation is considerable, 

 outside of high mountains, is the region from Greenland to 

 Francis Joseph Land, but here we have rather cold seas, which 

 are yet not entirely ice-bound even in winter. These seas are 

 more favorable to snowfall and glaciation than those around 

 Great Britain, because colder, and than those of the North 

 American archipelago, the Kara sea and the Arctic ocean near 

 Siberia, because less ice-bound in the cold season. 



4. The intense glaciation of the highest southern latitudes 

 gives an enormous quantity of icebergs floating northward, 

 that is to the seas of lower latitudes. As the surface of the 

 southern seas to about 62° S. is below 32° F., even in mid-sum- 

 mer, the icebergs cannot melt till they reach that latitude, and 

 their immense size enables them to reach sometimes even the 

 35° S. They certainly cool the waters, and thus produce con- 

 ditions favorable to glaciation even in lower middle latitudes. 

 This, besides, is a further direct cause of lower temperatures, 

 and an indirect cause of stronger and more extensive trade- 

 winds, which reach to beyond the equator and bring much 

 warm water to the northern hemisphere. The geographical 

 position is also favorable to this, especially the situation of Cape 

 St. Eoque and its vicinity. 



It is easy to see from all this, that there is no necessity to 

 seek for the reason of the difference of the northern and south- 

 ern hemispheres as to glaciation, by calling to aid the winter in 

 perihelion of the former and the winter in aphelion of the lat- 

 ter ; much simpler causes explain the result. The operation of 

 these causes is exceedingly well illustrated in the glaciation of 

 a part of the higher latitudes of the northern latitudes, while to 

 the east and west there is none, with lower mean annual tem- 

 peratures. 



