AND KIVEE VALLEYS BORDERING THE .BRITISH ISLES. 307 



adjoining the American continent and prolonged into the 

 North Atlantic, which have ah-eady been commnuicated. to 

 the Institute by Mr. Warren Upham,* and more recently by 

 myself, have induced me to take up the investigation of the 

 sub-oceanic region adjoining the British Isles with the aid 

 of the Admiralty charts of soundings, which afford most 

 ample materials for sucli investigation. The results, which 

 appear to me of remarkable interest, 1 now venture to place 

 before the Institute ; from which it will be found that all tend 

 to confirm the view of a former but very recent elevation of 

 the British and adjoining continental areas to the extent of 

 several thousand feet as compared with the level of the ocean 

 surface at the present day. 



II. Land connection ivith Iceland. — An examination of the 

 hydro graphical charts shows that it would be necessary to 

 raise the bed of the ocean to the extent of 1,320 feet (220 

 fathoms) in order to establish a land connection between 

 the British Isles and Iceland. The actual amount of eleva- 

 tion was probably greater and may have reached about (3,000 

 feet. The evidence for this will be seen further on, and it 

 corresponds very closely with the amount of elevation 

 determined for the coast of North America by the observers 

 already referred to.f Indeed all the evidence obtainable 

 by soundings goes to sliow that the whole area of the 

 North Atlantic has undergone stupendous changes of level 

 in very recent times both as regards emergence and submer- 

 gence. 



III. The British Platform. — The submerged terrace on 

 Avhich tiie British Isles and adjoining portions of Europe are 

 planted is generally known as "the 100-fathom platform." 

 It is often represented on hydrographical charts, such as 

 those of the late Professor Sir Wyville Thomson, by the 

 100-fathom contour taken from the Admiralty Chart.| But 

 this strict adherence to the 100-fathom contour is misleading 

 as regards the great physical features of the submerged 

 lands; and the same observation applies to the other 

 contours. These features vary in elevation and depression 

 according to geographical position ; and it is only by a close 



* Trans. Vict. Inst., vol. xxix. See also Prof. J. "W. Spencer on the 

 " Reconstruction of the AntilLiean Continent," Bidl. G'eoL Soc, America, 

 vol. vi. 



+ I have given a short preliminary notice of the results of my examina- 

 tion of the Admiralty charts in Nature, March 24th, 1898. 



X The Depths of the Sea, Plates II, IV, V (1873). 



Y 2 



