142 PROFESSOK EDWARD HULL, M.A., LL.D., F.E.S., T.G.S., ON 



floor of the ocean at depths descending to 6,000 or 7,000 

 feet.* 



These channels were determined by the aid of the 

 soundings on the Admiralty charts and were shown to have 

 all the characteristics in form and structure of some of t]ie 

 large canons of Western America and other countries ; and 

 their resemblance to many of the Norwegian Ijords is 

 equally striking. They were shown to be traceable at 

 intervals from off the Atlantic Coast of the British Isles, 

 and of Spain and Portugal to that of Africa, where the 

 Congo valley is continued for a distance of 120 miles out 

 under the ocean, traversing the Continental Platform and 

 opening out on the Abyssal Ocean at a depth of 1,200 

 fathoms, or 7,200 feet below the surface. These submerged 

 river-valleys Avere found to be referable to those of the 

 Loire, the Gironde, the Adour, the Douro, the Mondego, and 

 the Tagus ; this last, as well as the Adour, being actually 

 continuous with the existing river-valley; this statement 

 also applies to the Congo and to some of the rivers entering 

 the Mediterranean from the European side ; determined by 

 the late Professor Issel of the University of Genoa. 



2. Hiver-Yalleys necessarily Suh-aerial, 



As river-valleys can only be formed under conditions of 

 air and land the inference is inevitable that during their 

 formation those tracts, of the Atlantic below Avhich they 

 extend were under sub-aerial conditions, and that their 

 present submerged position is owing to subsequent 

 depression. Such depression must therefore have taken 

 place to the extent of about 6,000 feet along the whole of 

 the eastern border of the Atlantic; or to put the point 

 conversely, the former elevation as respects the level of 

 the ocean must have been about 6,000 or 7,000 feet, at 

 which depth the base-level of the Continental Platfornn 



* "Investigations regarding the submerged terraces and river- 

 valleys bordering the British Isles," Trans. Vict. Inst., vol. xxx, p. 305. 

 "On the Sub-Oceanic Terraces and Eiver- Valleys of Westei^n Europe."" 

 Ibid., vol. xxxi, p. 259. " On the Sub-Oceanic Eiver- Valleys of the 

 "West African Continent, and the Mediterranean Basin." Ihid.y 

 vol. xxxii, p. 147. Also, "Des investigations recentes relatives aux 

 Anciennes Vallees envahies par la mer des lies Britanniques et de I'oust 

 de I'Europe." Comptes Rendns du Congres Geologique International., 

 VIII Session, en France, 1901, p. 321. 



