OCT 1 1900 



THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE IV. VOL. VI. 



No. III.— MARCH, 1899. 



OI^Ia-Il^^JL^L JLi^TioXiDBS. 



L — On the Eastern Margin of the North Atlantic Basin.* 



By Wilfrid H. Hudleston, M.A., F.R.S., F.L.S., F.G.S., etc. 



(PLATE III.) 



IN offering a few remarks on a subject which beloTxgs>, in the first 

 instance, to the province of physical geography, .t will be 

 necessary for me to point out certain hydrographical details, wliilst 

 endeavouring to deduce from these details conclusions having 

 a geological bearing. Oceanography is almost a science in itself, 

 especially if we regard it from a geological point of view, as 

 something more than a mere description of water-spaces and 

 soundings. Ever since the days when the deep oceans were first 

 explored for the purpose of laying the telegraph cables some of the 

 leading facts were made known, and have since become familiar to 

 all students of physical geography. Such a feature, for instance, as 

 the Continental shelf, usually called the 100-fathom platform, which 

 supports the British Isles, the German Ocean, and its backwater, the 

 Baltic, has long since been made clear to us by the cartographer. 



The width of the submerged Continental shelf is very considerable 

 within the area of the British seas. It is generally considered to 

 represent a plane of marine denudation sloping gradually outwards 

 towards an ' edge,' which is approximately represented by the 

 100-fathora contour, although the real edge sometimes lies rather 

 deeper. This 'edge' is an important feature, since it indicates the 

 angle made by the Continental shelf with the suhoceanic Continental 

 slope, leading down into the oceanic abyss — what the late Dr. 

 Carpenter might have called the rim of the ' Tea-tray.' 



It is to this suboceanic Continental slope that I would chiefly 

 direct your attention, so far as it constitutes the eastern margin of 

 the Atlantic basin. Our limit on the south, for convenience, is the 

 30th parallel of North latitude ; and some approximation to the 

 suboceanic slope may be traced, in varying form and with great 

 difference in the angle of inclination, from the west coast of Africa 

 to the north-west of Spitzbergen. Its mean direction is slightly 



1 Eead in abstract at the Meeting of the British Association, Bristol, Sept., 1898. 



DECADE IV. VOL. YI. — NO. III. 7 



