39 
Chalk Cliffs near Dover . 
( :■ ' v.*’ { • . . ’ ' 
cause of the immense ruin lying beneath the cliff, at the extremity 
of which the signal-house stands. For the sea, having washed away 
the marie which formed the base of the cliff, the upper part, losing 
its support, has fallen down. The cliffs now forming an immediate 
barrier to the sea, have chiefly fallen from the stratum containing 
numerous beds of organic remains.* 
* Since writing the foregoing, I have received from my friend L. W. Dillwyn, Esq. 
t>f Pentlergare near Swansea, a letter, containing the following account of a sudden rise of 
this marie in the Bay, and opposite to the undercliff. 4 I promised you to endeavour to 
recollect and give you my observations on a small island which sprung out suddenly from 
the sea, about a mile to the eastward of Copt Point between Dover and Folkstone. I 
well remember, that whilst botanizing in that neighbourhood somewhere about the year 
1799, a fisherman told me that a gold mine had sprung out of the sea a night or two be- 
fore, and being puzzled to imagine his meaning, I begged him to conduct me to the spot, 
which he said was accessible at low water. As nearly as I can recollect, I found it tt) be 
about a acre or an acre and half in extent, and from eight to ten feet high, and so close 
to low-water-mark, as to be only accessible at spring tides. It was composed of a soft 
muddy marie filled with nodules of remarkably brilliant mundic, and containing nume- 
rous small nautili, which were more richly coated with nacre, and by far more irridescent 
than any others I had ever seen. On mentioning this island to my worthy friend the late 
Rev. John Lyons of Dover, he told me he thought he could account for its formation, 
and with a view to confirm an opinion which he had several years before communicated to 
the Royal Society (See Phil. Trans, for 1786), he accompanied me to the spot. Between 
the island and the chalk cliff in situ, and at the base of the latter, on the undercliff, we 
found rather a large morassy pool of fresh water. From this pool a considerable stream 
appeared to run underground in that direction, and to burst out again from the sands close 
to the island. I cannot sufficiently recollect the particulars of our observations, but as 
on examination we found that there had been a sinking of part of the cliff abruptly, I 
perfectly remember our conclusion was, that the slip of the cliff had occasioned a body of 
chalk to press suddenly and with great force upon a quantity of marie which had become 
softened by an underground stream, and forced it through the channel, so as to form an 
island at its mouth. Mr. Lyons had no doubt that it was the same stream which he told 
me he had seen losing itself gradually in the soil at some considerable distance inland, 
and which by loosening and softening an understratum of marie, had thus occasioned 
the superincumbent chalk to give way. Two or perhaps three years afterwards, I again 
visited the island, but it had then become, by the action of the waves, greatly reduced in 
height ; and, if I remember right, the marie which remained was nearly indurated. I 
have some of the above mentioned nautili, but they have lost most of their beautiful nacre, 
and owing to the late removal of my cabinets, I now hardly know where, nor have I time 
