354 Professor E. Hull — Submerged Terraces ^ Valleys, 



Donegal, at Slieve Liag, which rises in a bold heaclland of nearly 

 2,000 feet from the ocean. Here the margin of the British platform 

 is still closely represented by the 100-120 fathom contour, and the 

 escarpment descends to the 1,000-fathom line, from which the floor 

 of the ocean gently descends to a depth of about 1,600 fathoms 

 or 9,600 feet ; the form and height of the escarpment are similar to 

 those of section vii, but somewhat steeper. 



No. 3. This section is remarkable for two points : first, the width 

 of the British platform and the depth of its western margin below 

 the ocean surface. It is drawn from the coast of Clare, where 

 the cliffs of Mohir, formed of Carboniferous Sandstone, rise 400 feet 

 above the sea, along a series of soundings stretching due west for 

 a distance of 280 miles. The platform is here about 200 miles 

 across, and its western margin is indicated by the 200-fathom 

 contour very nearlj'^ ; that is, twice the depth of the margin opposite 

 Donegal and the Hebrides. The escarpment here, just west of the 

 "Porcupine Bank," is very bold and lofty; descending abruptly 

 from the 200 to the 1,500 contours, being a total descent of about 

 7,800 feet. Directly north of the Porcupine Bank, the escarpment 

 is quite precipitous, as the two terminal contours (the upper and 

 lower) are in close proximity. With this tremendous descent 

 of over 7,000 feet, the escarpment stretches southward, till opposite 

 the south of Ireland it sweeps round eastward, producing a wide bay 

 about 200 miles across, and sloping upwards to the marginfl line of 

 200 fathoms. Opposite this bay the floor of the ocean descends 

 to a depth of 2,500 fathoms (or 15,000 feet) within a distance of 

 200 miles. 



No. 4. This section is drawn from the coast of Kerry in a south- 

 westerly direction', and is continued eastward over Carantual, the 

 highest mountain in Ireland, i-eaching a height of 3,400 feel above 

 the sea. The platform is here only 60 miles across, and the descent 

 from its margin is less precipitous than in the case of Sections 2 

 and 3. The depth of the margin is about 200 fathoms, and after the 

 initial steep descent to about 1,500 fathoms, the ocean bed gently 

 declines, till, at a distance of 170 miles from the margin, it reaches 

 a depth of 2,300 fathoms or 13,800 feet. This is the last or the 

 sections I have drawn, but if another were taken in a south-westerly 

 direction from Ushant, off the coast of France, it would show 

 a platform of 80 miles in breadth, breaking off at the 200-fathom 

 line in a sheer precipice of 5,000 feet just south of La Eochelle 

 Bank, which is situated ?t the edge of the platform itself. 



"We have now reached the southern limit of the region which 

 I have proposed to myself for investigation at the northern end 

 of the Bay of Biscay, but I do not doubt that the features hsre 

 described are continued still further south. ^ From what has been 

 stated it will be seen that throughout a line of coast of 600 or 700 



1 This statement I have since verified by an examination of the Admiralty chart 

 over the Bay of Biscay, which affords most interesting results, especially in the 

 determination of the chan lels of the rivers Loire and Adour traversing the platform, 

 and descending through deep canons to the base of the great escarpment. — E. H. 

 (April, 1898). 



