THE GEOLOGY OF THE ENGLISH CHANNEL. 161 



materials, long after the forms of the shells have ceased to be recog- 

 nisable. The sea-bed, particularly on the French side of the Channel, 

 is mainly composed of shell sand, or sand in which few particles of any- 

 thing but such as show shell-structure occur. Areas of this character 

 are laid down by the French surveyors, and occur in the interval 

 between the Land's End of France, or TJshant, and the Little Sole 

 Bank; yet on the sides of this bank, and more particularly on its 

 western slopes, large, perfect, though decayed, shells again occur, and 

 what is more remarkable. Patella vulgata, Turbo littoreus, etc. Taking 

 the two phoenomena together, the occurrence of littoral shells and of 

 marginal shingle, we may safely infer that we have at this place the 

 indication of a coast-line of no very distant geological period, buried 

 under a great depth of water, and removed to a great distance from 

 the nearest present coast-line." 



"... In the very coarse beds which form the floor or lowest levels of 

 the deeps in the upper part of the Chanliel, from the meridian of Cape 

 la Hague eastward, and which have a depth of forty and fifty fathoms, 

 we also seem to have the highest marginal zone of some former period, 

 over which the drifting beds of the actual period are spreading ; and, 

 on the other hand, such masses as Jones Bank are to be considered as 

 protruding portions of an older sea-bed isolated amidst the ooze 

 deposits of the present sea." 



". . . The character of the greater part of the Channel area, if laid bare, 

 would be that of extensive plains of sand, surrounded by great zones 

 of gravel and shingle . . . ; whilst along the opening of the Channel 

 there is an obvious configuration of hill and valley, and an amount of 

 inequality equal to that of the most mountainous part of Wales." 



Delesse attributes more to the action of currents in the deeper 

 parts of the Channel than apparently would Austen, but agrees that 

 the coarser deposits are not of the present epoch, and argues that the 

 settlement of the sands and silts of to-day has been prevented in 

 certain areas by the strength of the currents, and hence these earlier 

 deposits have been preserved from being covered. He writes ^ : — 



" La Manche etant balayee par des courants energiques, on doit 

 s'attendre a ce que son fond ne regoive pas partout des depots, mais 

 soit au contraire forme tres souvent par des roches pierreuses 

 anterieures a I'epoque actuelle; c'est, en effet, ce qu'apprennent les 

 sondages, et proportionnellement ces dernieres roches y occupent 

 meme une etendue beaucoup plus grande que dans les autres mers. 

 D'abord, elles presentent des surfaces tres vastes dans tout I'Ouest de 

 la Manche ; elles bordent la Bretagne et la Cotentin auquel elles 



' Lithologie des Mcrs de France, p. 308 et seq. 



