458 DEPTHS OF THE OCEAN 



north of Denmark Strait, Spitsbergen, Franz -Josef Land, 

 Novaya Zemlya, the coast between the White Sea and the 

 Kara Sea, as well as the plateau of Jan Mayen and the 

 deep central basin of the Norwegian Sea, 



In addition to these purely boreal and purely arctic areas 

 there are transitional areas, designated boreo - arctic, which 

 may be found wherever boreal and arctic water-masses meet 

 Such areas occupy more or less extensive tracts, and exercise 

 a distinct influence upon the distribution of the fauna. The 

 temperature is not so high as in the boreal region, except 

 perhaps at the surface, varying between o" C. and 3° or 4 C, 

 though in the shallower parts a far higher temperature is found 

 in summer, due to the heat of the sun, and as a result there 

 are certain boreal littoral forms that occur also in the boreo- 

 arctic region. 



The following are boreo-arctic areas : the south - western 

 portion of the Barents Sea, from the East Finmark and Murman 

 coasts to the White Sea, where a branch of the Gulf Stream, 

 flowing eastwards, is gradually blended with arctic water ; the 

 north and east coasts of Iceland, where branches of the Gulf 

 Stream unite with the East Iceland Polar Stream^ ; the Iceland- 

 Faroe ridge, where the East Iceland Polar Stream meets the 

 Gulf Stream ; the Wyville Thomson Ridge, over which the Gulf 

 Stream passes into the Norwegian Sea, where a mixture of 

 the two waters undoubtedly takes place, but this boreo-arctic 

 area is of small importance compared to the others ; and the 

 continental slope on the eastern side of the Norwegian Sea, 

 where there is a narrow area of mixture between Atlantic 

 water and arctic water, resulting in temperatures slightly higher 

 than o" C. A weak branch of the Gulf Stream flows along the 

 west coast of Spitsbergen, giving rise to a very limited boreo- 

 arctic belt, though, generally speaking, the west side of 

 Spitsbergen must be considered purely arctic. The shallower 

 parts of the coastal waters, as well as the inner portions of the 

 fjords, from Lofoten to the North Cape, are boreo-arctic. 



North The topographical conditions in the North Atlantic are 



Atlantic, rnych like those of the Norwegian Sea, but the hydrographical 



conditions are dissimilar. On the eastern side the coast banks 



of both Europe and North-West Africa are bathed by much 



warmer water than those of corresponding parts of the Nor- 



' I ought to state, however, that owing to the influence of the East Iceland Polar Stream 

 the north-eastern coast must perhaps be considered a purely arctic area. 



