CHAPTER II. 



THE OCEANOGRAPHY OF THE NORTH-WESTERN OCEAN i. 



The British Islands and the Continental Shelf. It is well 

 known that the British Islands are situated on an elevated portion 

 of the ocean bed which forms a continuous edging round the 

 continent of Europe — this is the "Continental shelf" or "Con- 

 tinental slope." If we draw an imaginary line round the British 

 Islands which connects all places on the sea bottom where the 

 depth of water is 200 metres, or roughly 100 fathoms, we shall 

 find that this line includes all these Isles, and that within it the 

 sea is, with the exception of two or three isolated spots, as in the 

 Channel between the coasts of Scotland and Ireland, and at the 

 entrance to Loch Fyne and elsewhere, nowhere more than that 

 depths If the sea bed round our land were raised 600 feet the 

 water frontiers of the United Kingdom would disappear. 



If we glance at a hydrographic chart of the North-Atlantic 

 Ocean we shall find that the 2000 metre line forming the limit 

 of the continental area is situated at a comparatively short 

 distance from the coasts of Africa and Southern Europe, and is 

 there at certain places no more than about 50 or 60 miles from 

 the coast. Out from the coasts of Gal way this line is very near 

 the land and the ocean bed slopes very steeply down to abyssal 



^ By this term is to be understood not only the North Atlantic proper, but also 

 the Norwegian Sea, the Arctic Sea, the North Sea and the Baltic. 



^ Off " Skate Island" in Lower Loch Fyne a sounding of 107 fathoms has been 

 made (Mill, British Association Handbook, Glasgow Meeting, 1902). There is a 

 depth of 149 fathoms in the deep "gutter" between Belfast Lough and Wigtonshire. 

 Some of the Scottish inland Lochs (Loch Morar and Loch Ness), are also very deep. 

 A sounding of 170 fathoms has been made in Loch Morar, which is only about 

 31 feet above sea level (Scott, Ann. Rep. Fishery Board, Scotland, for 1892, Pt. in. 

 p. 221). The bottom of this fresh- water loch is therefore lower than any part of 

 the North or Irish Seas. 



