182 BIOLOGY OF THE SEAS OF THE U.S.S.R. 



accounts for 13 km 3 . So that inflow exceeds discharge by 191 km 3 . If this 

 excess were distributed over the whole surface of the Sea, it would form a 

 2-2 m layer of fresh water, or one-fortieth part of the volume of the Sea. 



Bottom topography 



The greatest depth in the White Sea is about 330 m (off Cape Tury), and its 

 central part is occupied by depths greater than 100 km, separated by the wide 

 ridge of the Voronka and the Gorlo from the deep parts of the Barents Sea. 

 The average depth of the basin is 110 m. 



The deep bottom of the Gulf of Kandalaksha, which represents what in the 

 Ice Age was the bed of a great glacier, is covered with moraine deposits and 

 forms a series of depressions, which are separated on the seaward side by 

 banks (end moraine). Along its shores are a great number of inlets and islands. 

 The character of the Dvina Gulf, which receives the waters of the great 

 Northern Dvina river, is, however, quite different. Sandy deposits are pre- 

 dominant here ; the bottom slopes evenly down to the bed of the Sea, and the 

 shores have few inlets and islands. No less peculiar is the Gulf of Onega, 

 relatively shallow (20 to 40 m) and situated on a rocky plateau. It is separated 

 from the Sea by the Solovetsky Islands and has innumerable islands and 

 underwater shoals scattered about it. 



Climate 



In spite of the fact that the climate of the White Sea is considerably more 

 continental in character and much more rigorous in winter than that of the 

 Barents Sea, yet it is completely marine in character. At the same time the 

 climate in the open parts of the Sea is milder than in the inlets and bights, as 

 may be seen from Table 77, giving the mean monthly temperature for the 

 Solovetsky Islands and for Archangel. 



Table 77 



Ice cover 



In consequence of its climate, which is harsher than that of the Barents Sea, 

 considerable masses of ice are formed in the White Sea in winter and persist 

 for about half the year, sometimes for seven months (in the region of Mudyug 

 Lighthouse) — from the second half, or from the end, of October till the middle 



