272 PROF. E, HULL, LL.D., ETC., ON THE SUB-OCEANIC 



observations round the coast of France and the Bay of 

 Biscay soutliwards to the entrance of the Straits of Gibraltar 

 embracing a distance of about 1,500 miles along the coast, 

 containing numerous very interesting features, such as we 

 now meet witli on the surface of the land, consisting of 

 terraces, escarpments, and river-valleys. 



Part II. 



I. The Continental Platform. — This gently sloping 

 terrace, stretching seawards from the coasts of France, Spain, 

 and Portugal, is continuous with that on which the British 

 Isles are planted. As far as I can ascertain it was first 

 indicated in Dr. Stieler's Hand Atlas.* Its margin is shown 

 by the 100-200-fathom contour; but there are no indications 

 given there that it is trenched by channels resembling those of 

 rivers on the land. On the Physical Chart of the World of 

 tlie " Challenger " expedition, the general form of the 

 British-Continental Platform is approximately indicated by 

 the 1,000-2,000-fathom contours, but the scale is too small 

 to show details, and there are no hidications of clefts or 

 river-valleys.f The chart of Perthes seems to have been 

 generally followed by subsequent writers. The newest 

 sub-oceanic map is that of Mr. Hudleston, F.R.S., showing 

 the platform— but not the river- valleys.^ 



Opposite the coast of France, at Brest, the platform is 

 about 130 miles in breadth, where it enters the Bay of 

 Biscay ; and here, owing to the recession of the coast, the 

 breadth reaches over 100 miles, but becomes gradually 

 narrower southwards. Along the north coast of Spain 

 the platform becomes imusually narrow, averaging only 

 from 20 to 30 miles outward from the coast to its margin. 

 Off Cape Finisterre, and west of the coast of Portugal, the 

 breadth varies from 30 to 40 miles and then gradually 

 increases southwards till, off Cape St. Vincent, it appears 

 to widen oat and terminate in a succession of terraces ; 



* Published by Justus Perthes. Gotha, 1872. 



+ Published 1873-6. 



I Geological Magazine, March, 1899, p. 97. 



