TEEKACES AND RIVEE VALLEYS Oh' WESTEEN EUEOPE. 279 



bed at that place. Owing to this part of the old channel 

 lying in the line of the present tidal currents where they are 

 very swift (from eight to nine miles per hour), the channel 

 has been kept clear ; while above and below, where the shores 

 of the English Channel recede, the silting has nearly 

 obliterated the course of the original stream.* 



V. The Submerged River-Channels of the Bay op 

 Biscay. — Still more remarkable, than those already described, 

 are the submerged river-channels of the Bay of Biscay. 

 Those of the Loire. Adour, Caneira are the most important ; 

 but besides these are several bays, trenching deeply into 

 the Continental Platfoi'm which were clearly the embouchures 

 of streams the upper channels of which cannot now be 

 definitely determined from the charts. 



(a.) The Loire. — In the case of the Loire, the Continental 

 Platform is so broad, about 100 miles, and the river-channels 

 have been apparently so much silted up, that there is 

 difficulty in tracing the connection of the caiion, which, 

 from its position may be supposed to have belonged to this 

 stream, with the Loire itself. Indications of a channel may 

 be observed, from the soundings, S. of Belle lie, and again 

 at a distance of 50 to 60 miles further W. in long. 4° 10' W. ; 

 and from this point to long. 5° 30' W. ; lat. 47" 10' N., where 

 the caiion is fully developed, the channel may be traced 

 continuously by the depression in the soundings below the 

 general floor of the Platform. Here it takes the form of 

 a double canon (see Plates I and III), with which it passes 

 down to the abyssal floor at a depth of about 1,500 fathoms. 

 This bifurcation of the channel on reaching the edge of the 

 oceanic slope is not uncommon in the case of several of the 

 larger river-channels such as those of the Adour and Tagus. 



(b.) The Gironde. — A well-defined bay pointing N.E. breaks 

 through the Great Declivity in long. 2° 40' W. ; and lat. 44° 

 55' N., which I have inferentially connected with the above- 

 named river, distant about 70 miles: but the soundings are 

 not sufficiently numerous to enable us to follow the con- 

 necting channel across the wide expanse of the Platform. 

 As this large river must have entered the ocean somewhere 

 about this position, the inference seems justifiable. 



* " The Hurd Deep " was so called by Captain Martin White, who 

 sounded over it, after the hydrograjDher of the day, Captain Hiuxl, anno 

 1810, as I am informed by Admiral Sir William Wharton, F.E.S. (4th 

 Mav, 1898). 



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