W. H. Mudleston — E. Margin of N. Atlantic Basin. 153 



continental slope is very steep. I will give two instances. (1) Off 

 Kivadeo the lOU-fathom platform is of unusual width for this coast — • 

 nearly 30 miles, in fact ; from the edge of this platform a depth of 

 1,130 fathoms is obtained in the next 5 miles, giving an incline of 

 ] in 4, or about 13°. It is probable that this is a hole, and there 

 are indications of still steeper gradients in the vicinity, since at some 

 little distance outside the edge of the shelf a small bank is marked 

 vi'ith only 63 fathoms of water, within 3^ miles of the depth in 

 question ; this shows a gradient of nearly 1 in 2, or 25°. (2) Exactly 

 off Gape Ortegal itself the 100-fathom platform has a width of 

 15 miles; from the edge of this platform a depth of 2,515 fathoms 

 is obtained in the next 13 miles. This gives a gradient of 1 in 5, 

 or 11°, for the suboceanic continental slope off Cape Ortegal. In 

 this case, if we reckon the total distance from the coastline rather 

 than from the edge of the continental shelf, we obtain a fall of 

 2,515 fathoms in 28 miles, showing a gradient of 1 in 10, or rather 

 less than 6°. 



It is now time for me to glance briefly at some of the geological 

 infer-ences which have been drawn from the bathymetrical conditions 

 made known in connection with the Bay of Biscay and its 

 surroundings. It will be hardly necessary to say that Professor 

 Spencer sees canons, cirques, and escarpments in all these things ; 

 whilst in Professor Hull the American epeirogenists have found 

 an able ally on this side of the Atlantic, as shown in his recent 

 '' Investigations regarding the Submerged Terraces and River Valleys 

 bordering the British Isles." ^ Professor Hull wields his pencil so 

 skilfully under the guidance of the scientific imagination that we 

 cannot fail to be interested in his charts and diagrams, even if 

 we do not in all cases agree with his interpretations. 



So long as Professor Hull confines himself to tracing the old 

 river-courses cut in the continental shelf he is pretty safe.^ This 



^ Trans. Victoria Institute, 1898. 



* At the meeting held in the Map Room of the Royal Geographical Society (Jan. 27) 

 for the purpose of hearing and discussing Professor Hull's latest paper on this subject, 

 some of the speakers were disposed to criticize his tracing of the old river-courses cut 

 in the continental shelf — e.g. the River of the English Channel. But this really is 

 a very minor matter, and altogether fails to touch his principal contention. IVl ost 

 persons who have paid attention to the physical geography, past and present, of these 

 Islands agree that the area of the English Channel was at one time sufficiently elevated 

 as to have been within the influence of meteoric erosion : a difference of 100 fathoms 

 would more than effect this. Thus we may readily allow Professor Hull his rivers 

 of the English and St. George's Channels, even if we are disposed to criticize the 

 exact course they may have taken. But the deep sculpturing which he claims to have 

 been effected in the suboceanic continental slope (the ' escarpment ' of Professor Hull) 

 by these same rivers involves considerations which would land us in serious difficulties. 

 If the 'edge' or angle of the slope was at one time raised 1,000 fathoms above 

 the level of the sea, instead of being 100 fathoms below it as at present, in that case 

 the region now occupied by the EngUsh Channel must have been raised to that extent 

 or more, imless the River of the English Channel was endowed with the faculty of 

 running up hill. Suppose we take the period as Pliocene : this means an upland of 

 6,000 or 7,000 feet above sea-level in the vicinity of the region now occupied by the 

 Straits of Dover, whilst some sixty miles to the northwards the Crags were being 

 deposited in a shallow sea, whose area is now partly occupied by the v'Suffolk coast. 

 Tridy, in this case we should require another ' escarpment ' facing the area now 



