280 PROF. B. HULL, LL.D., ETC., ON THE SUB-OCEANIC 



(c.) The Adour. — Of all the sub-oceanic river cliaiinels to be 

 met with along the coast of Western Europe, none are so 

 strikingly developed as that of the Adour. This fine river 

 has its sources amongst the highest valleys of the central 

 Pyrenees and enters the ocean at the base of this range near 

 Bayonne. It is unique in this respect, that its submerged 

 channel is continuous with the existing stream from its present 

 mouth to its ancient embouchure at a distance of about 100 

 miles from the coast of France, and the channel is recognised 

 on the Admiralty chart for some distance from the sliore under 

 the name of '•' La Fosse de Cap Breton."* This channel 

 reaches a depth of 175 fathoms (1,050 feet) at a distance of 

 five or six miles from the shore, and 117 fathoms (702 feet) 

 below the surface of the Platform. At 15 miles from the 

 same point, another channel joins that of the Adour on the 

 south side, and from this point it rapidly deepens, assuming 

 the form and features of a grand canon, bounded by steep, 

 sometimes precipitous, walls of rock from 4,000 to 6,000 feet 

 in height, and ultimately opening out on to the floor of 

 the onean at a depth of about 1,000 fathoms (or 9,000 feet). 



A few miles above the embouchure the channel bifurcates 

 (Plate I), the two arms embracing a tract (once doubtless 

 an island) of shallower ground; but the arms ultimately 

 converge on the floor of the abyssal ocean. Between the 

 canon of the Adour and the coast of Spain to the south, the 

 continental shelf is remarkably narrow, ranging in breadth 

 from 6 to 20 miles, and is indented by several short but 

 deep bays or ravines along which, we may well believe, 

 streams descended from the northern slopes of the western 

 Pyrenees in a succession of rapids and cascades, of which 

 the Rio de Bilbao was doubtless one of the most important. 

 Several branching canons with their existing streams on the 

 mainland are clearly defined by the contours as shown in 

 Plate I. At the period when all these features wei'e 

 sub-asrial, and Avhen the Atlantic waters washed the base 

 of the Grand Declivity, the scenery of the canon of the 

 Adour must have resembled in no small degree that of the 



* M. Elisee Reckis* abandons the attempt to explain tlie origin of this 

 reniarkalile " gulf " when he says : — 



" But how can we explain thatsincrular gulf which extends immediately 

 in front of Cape Breton on the Coast of Landes ? Ought we to attribute 

 its formation to the meeting of the tides, which takes place in the channel 

 of the Gulf of Gascony 1 This is a question which it is not yet possible 

 to decide." — The Ocean, Section I., p. 7. The author claims to have 

 solved the problem which Reclus relegates to the future ! 



