40 THE OCEANOGRAPHY OF THE NORTH-WESTERX OCEAN [PART I 



which are above the level of 400 m. from the surface pass over the 

 ridge. 



Surface: 



Metres 



-looo 



Fig. 16. Similar section. Shews the distribution of water of various 



degrees of salinity. 



On the Atlantic side the temperature of the sea is highest at 

 the surface and then falls rapidly for the first two hundred metres 

 until we reach a kind of boundary between the variable warm 

 water at the surface, which is considerably influenced by the 

 seasons, and that lying on the sea bottom. From this level the 

 sea cools less rapidly down to a depth of about 1000 metres and 

 then it cools very slowly down to the bottom where there is 

 a temperature which does not vary and is about that of the 

 freezing point of fresh water. On the Norwegian side the con- 

 ditions are very different. There is a surface stratum which is 

 about 600 metres from the surface and in which variations may 

 occur, the temperature ranging from 1'5° C. to about 8° C, but 

 below this the water has a uniform temperature which is about 

 0° C. while in the deepest parts it is as low as — 1'3° C, lower than 



