THE WHITE SEA 



191 



The sea-bed 



The soils of the White Sea floor present every stage from cliff- and rock-bed 

 along the shore and in the Gorlo to red clay in the central part (Fig. 84). In 

 the Voronka and the Gorlo of the White Sea the sea-bed is covered with sand, 

 shell gravel and stones, and in the Gorlo also with outcrops of cliff. The basin 

 of the White Sea is mainly covered with very soft soils. Sand and silty sand 

 run in a comparatively narrow strip along the shore. 



Hard floors are widely distributed only in the Dvina Gulf, and especially 

 in the Gulf of Onega. In the Gulf of Kandalaksha a very large number of 



Fig. 84. Distribution of the soils of the White Sea (Gorshkova, 1957): 1 Less 



than 5 % fine-grain fraction ( <001 mm) ; 2 From 5 to 10 % fine-grain fraction; 



5 10 to 30% ; 4 30 to 50% ; 5 Clayey mud ; 6 Mud ; 7 Sandy silt. 



rocks is observed, obviously of moraine origin ; in the Gulf of Onega there is 

 much variegation of the soils, which is dependent on the complicated system 

 of currents. Outcrops of cliff are encountered here, and soft muds. 



According to the data of T. Gorshkova (1957) the content of organic carbon 

 in the sediments of the open parts of the White Sea (Fig. 85a) varies from 009 

 to 2-2 per cent, and for the whole of the White Sea the average is 1-14 per 

 cent. In the enclosed parts of the inlets and gubas the highest percentage of 

 organic carbon reaches 4-37 at the expense of enrichment by vegetable re- 

 mains. These data are a good illustration of the direct interdependence of the 

 quantity of organic matter and the mechanical composition of the sea-bed 

 — chiefly of organic matter and muddy sediments (Fig. 85b). 



