Day — Ancient Beach and Submerged Forest. 113 



forest pretty well beyond all doubt. Subsequently, on examining 

 this bone in the presence of Mr. Etheridge, some of the greenish 

 grey sand contained in it fell out, and we observed in this a specimen 

 of a small Planorbis and one of Bithynia tentaculata, which show the 

 freshwater origin of this infilling. I have little doubt, from the 

 presence of the Chalk pebbles in the bottom of the peat bed, but 

 that this is a continuation of the similar deposit overlying the raised 

 beach, although I observed no stumps of trees in the latter. The 

 sand contained in the bone is very similar to that overlying the 

 shingle, and I now am sorry that I did not examine the latter to 

 see if it be not also of freshwater origin. Should it prove to be so, 

 its very close association with the bed below would possibly lead to 

 the conclusion that the latter was not a marine but a freshwater 

 beach, formed upon the shore of a lake or estuary. I merely 

 suggest the possibility of this, as the " present conformation of 

 Wissant Bay is such as to remind us that an elevation of this 

 district would, in past times, when all the hard rocks were more 

 prominent than now, have had the effect of converting it into an 

 almost basin-shaped depression; the Portland beds to the westward 

 and the Chalk to the north forming part of an elevated rim roiind a 

 hollow scooped out in the Kimmeridge and Oxford clays and the Gault 

 and Greensands. The correlation of the formations just described 

 with those near Sangatte must be dependant upon the determination 

 of this question ; for if the Wissant beach is of lacustrine origin, 

 then it is probably contemporaneous with the Sangatte Chalk-rubble, 

 and the '' head" of the latter with the forest, the Sand-dunes being 

 more modern than either. On the other hand, should both beaches 

 be of the same date, then the forest would have been coeval with 

 the accumulation of the Chalk debris and the formation of the 

 "head" probably with that of the Sand-dunes. I do not believe, 

 however, that the latter are of the most modern date, for the con- 

 figuration of the coast, and the fact that the raised beach and the 

 ancient forest are now being laid bare, show clearly that the sand is 

 being cut away on its seaward edge, and that, consequently, it is but 

 a remnant of a more extensive series of dunes. 



The consideration of this question has suggested another enquiry 

 to my mind. Why has Wissant ceased to be a port ? for formerly it 

 was one of some little importance, and now it can scarcely be called 

 a fishing village. The answer generally given would probably be 

 that the growth of the Sand-dunes had obliterated its harbour ; but 

 if it be true that the sands are being cut away, this explanation will 

 not hold, and I myself think that a far more tenable view is to be 

 based upon the geological structure of the subaqueous part of the bay. 

 If we look at the map (PI. VII. Fig. III.) we see that a shoal having 

 less than a fathom of water on it at lowest tides, extends from Cap 

 G-ris-nez, in a north-easterly direction, in such a manner as to cut ofi^ 

 a channel about half-a-mile in width , and having a depth of from two 

 to three fathoms of water in it, directly abreast of Wissant. The 

 shoal is probably owing to an accumulation of masses of grit, the 

 remains of the Kimmeridge and Portland strata that once covered 



VOL. III. — NO. XXI. 8 



