1012] on The North Sea and its Fisheries. 417 



that the 100-fathom line bounds, the fisherman finds his place and 

 calling. Here and there in the world, as for instance, off the coast 

 of Portugal, are isolated deep-sea fisheries ; here and there the 

 adventurous trawler, or halibut-fisher, plies his craft on the deeper 

 slopes of the continental shelf to 200 fathoms, or a little more ; but 

 broadly speaking, the 100-fathom line bounds and limits the ordinary 

 operations of the fisherman. Where that continental shelf narrows, the 

 fisherman's field is narrowed ; where it widens out, he finds an ampler 

 range ; and in the region of the White Sea and the Murman coast, 

 the whole of our North Sea area, in a belt round our western coasts, 

 a broad girdle round France, a narrow one off Portugal and Spain, 

 here and there in Africa, as off Morocco and down in Greyhound 

 liay — in all of these regions the continentiil shelf or plateau extends 

 its rich and productive bed a long way from the land, and yet but a 

 little way into the territory of Ocean. 



What I have called the gateways of the North Sea are not 

 merely highways of commerce, they are the doors l)y which Ocean 

 itself enters into the narrow seas, bringing with it its quickening 

 influence on life, and its regulating and ameliorating effects on 

 climate ; and there have been times when one or another, or all, of 

 these gates were closed. It is to the opening or shutting of these 

 gates, and of others leading to more southern seas, that the geologist 

 ascribes much of the successive changes of climate and of fauna 

 during Tertiary times. 



The topography of the North Sea, as well as of our land, bears its 

 fragmentary records of these old times. The Dogger Bank is 

 perhaps but a great moraine, and over it (when the great ice-cap had 

 passed away) roamed the rhinoceros, the reindeer and the mammoth. 

 The deep groove off Norway was probably in part a channel whereby 

 the river system of eastern Europe ran seaward, in part an eddy, 

 where the Scandinavian glaciers gripped and scooped their hardest, 

 and first of all, probably a great crumple in the earth's crust. In the 

 Moray Firth a deep channel, more than a hundred fathoms deep, 

 exists ; it is the course by which an older and greater Spey ran tribu- 

 tary into an older and greater Rhine. 



Apart from the groat tidal waves that roll in twice a day from 

 the ocean round by our northern and southern gates, the great domi- 

 nating movement of our seas lies in the Atlantic current, or system of 

 currents, that we commonly call the Gulf Stream. The Gulf Stream 

 itself is a river in the ocean (as Maury called it) ; but partly as a 

 river, and in part as a great, wide, slow-drifting flood, the warm 

 waters of the bosom of the Atlantic creep ever northward and east- 

 ward to bathe our shores, and to soften the climate of sea and land in 

 northern Norway and distant Spitzbergen. A little branch of the 

 current enters in by the southern gate, a somewhat greater eddies 

 round the north of Scotland, and under these two impulses (aided by 

 local differences in the density of the waters of the North Sea basin) 



