152 W. R. Hudleston — E. Margin of N. Atlantic Basin. 



a depth of 205 fathoms close to the coast, and which may be traced 

 for 30 miles out to sea until it attains a depth of over 600 fathoms. 



This curious place has generally been regarded as the submerged 

 channel of the predecessor of the river Adour, which now enters 

 the sea a few miles to the southwards. To this point I will draw 

 attention presently. Meanwhile there are a few hydrographical 

 details in connection with this submerged channel which might 

 be mentioned. Like so many sunken channels and fjords, not 

 excepting the so-called Channel of Norway, it is very deep at the 

 head, deeper in fact than in any other portion of the first 15 miles. 

 There are also indications of a lateral channel (a short cirque having 

 a depth of 336 fathoms). The mouth is about 10 miles across, and 

 has a maximum depth of 530 fathoms below the submerged 

 continental shelf. This gives a slope from the edge of the shelf 

 to the centre of the channel of 1 in 8, or 7°. 



Thirty-five miles to the westward another channel is marked on 

 the chart, in presumed continuation of this one ; it is situated about 

 30 miles to the north of the town of Bilbao. In this channel depths 

 ranging from 1,000 to 1,500 fathoms occur, apparently sunk in 

 a submerged platform, which itself has an extremely irregular 

 surface. A map of the soundings at this place is given by Professor 

 Milne, who quotes it as a locality notorious for cable fracture.^ He 

 states that the fractures usually happen in the month of March, 

 when sometimes portions of the cable, four or five miles in length, 

 are buried. The fractures are attributed to the action of a submarine 

 current, caused by the piling up of surface water, cutting the 

 prolongation of a river bed with steep walls ; these walls when 

 undercut are believed to fall in such masses as to bury the cable. 

 No rock is marked in these soundings, which yield clay, stiff clay, 

 mud, and sand. In this locality the 100-fathom line lies 12 miles 

 off the coast ; and from this edge to the 1,500-fathom sounding in 

 the supposed channel is a distance of 11 miles. This gives a mean 

 slope of 1 in 7, or 8°, but pitches much steeper than this in all 

 probability occur. There are several indications that this depth of 

 1,500 fathoms represents a hole rather than a channel, for the next 

 sounding seawards shows only 1,250 fathoms. 



Certain bathymetrical features in connection with the Bay of 

 Biscay may be mentioned here. The deepest sounding shown on 

 the chart (No. 1,104), viz. 2,788 fathoms, is about 100 miles north- 

 west of the supposed channel or caiion of Bilbao. From this depth 

 the floor of the bay, according to the soundings, rises very slightly 

 towards the ocean. If this floor was uplifted equally to the extent 

 of 2,700 fathoms, or 16,200 feet, there would remain a depression 

 of limited extent, 88 fathoms deep, about 100 miles N.N.W. of 

 Santander; all the rest of the floor of the bay would be dry land. 

 Generally speaking, deep water follows pretty closely on the 

 Cantabrian chain. In the vicinity of Cape Ortegal, where the coast 

 of Spain begins to trend south-west, before assuming a southerly 

 direction off Cape Finisterre, there are cases where the suboceauio 

 1 Geographical Journal, September, 1897, p. 273. 



