

450 DYNAMICAL GEOLOGY. - [Boox II. 
being in a general way prolonged below it. The belt of beach 
forms a kind of terrace or notch along the maritime slope. Some- 
times, where the coast-line is precipitous, this terrace is nearly or 
wholly wanting. In other places it runs out a good way beyond low- 
water mark. On a great scale the floor of the North Sea and that 
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Fig. 169.—Mapr or British SUBMARINE PLATFORM. 
The darker tint represents sea-bottom more than 100 fathoms deep, while the paler 
shading shows the area of less depths. ‘The figures mark the depth in fathoms. The 
narrow channel between Norway and Denmark is 2580 feet deep. 
of the Atlantic Ocean, for a distance of 300 miles to the west of 
Ireland, may be regarded as a marine platform that once formed 
part of the European continent (Fig. 169), and has been reduced by 
denudation and subsidence to its present position. 
So far as the present régime of nature has been explored, it 
would seem to be inevitable that, unless where subterranean 
movements interfere, or where volcanic rocks are poured forth at 

