67 



and slips, but is not readily dissolved with water. Clay absorbs 

 moisture very readily, and expands very much during that 

 process ; on drying, it parts with its moisture readily, and 

 contracts very much in so doing — hence, when London clay 

 cliff is subject to altermations of moisture and drought, it 

 is constantly in motion as far as these influences extend ; 

 though the London clay readily absorbs moisture when dry, it 

 is anything but porous when saturated with moisture, but, on 

 the contrary, is most impervious. So it happens that such 

 shores (as those of Sheppy, for instance) are constantly falling 

 into the sea, and, under the influence of its action, is washed 

 away like sugar in water ; for though not soluble, its particles 

 are so small and light that they are most readily separated and 

 carried away by the sea in suspension. It is no wonder, then, 

 that we find a few centuries produce great changes in such a 

 coast-line. Our historical evidences show great loss of the 

 shore along this north side of Kent ; whereas we have seen on 

 the south rather a gain in some parts. That a further extension 

 of the high cliff's at Shepp)^, in a northerly direction, would 

 exercise a most important influence in directing the current of 

 the Medway river, and directing also the waters of the Thames, 

 we must admit. I have few facts to guide me as to this coast in 

 early times, but a map in Queen Elizabeth's reign shows that 

 the Medway turned to the north by the Isle of Grain more than 

 it does at present ; also, that there was then a deeper and 

 broader channel south of Sheppy and the Swale, while the 

 marshes of Upchurch and Halstowe appear less subject to the 

 water of the Medway than at present. However this may be, 

 there must have been great changes since the Roman period of 

 a minor character, which render it impossible to reconstruct the 

 coast. The large discoveries of Roman remains, quite up to 

 the marshes now indundated at high water, might indicate that 

 the land was higher then than at the present time. But I have 

 shown, when speaking of the Stour, that it was quite possible 

 for land to be so low that it would be covered by the sea at high 

 water, but yet, being distant from the sea-shore, to be protected 

 by the length of its waterway. In the case of Sandwich and 

 Canterbury, the sea has been getting annually further off"; while 

 in the case of Sittingbourne, it has been getting gradually 

 nearer. 



GENERAL CONCLUSION. 



In my former papers I alluded to M. Goslet's papers on the 

 Coast of Calais and St. Omer, as showing that, at the Roman 

 period a large tract of land, since covered with water, had been 

 used and populated by them. Then about the third century an 

 invasion of the sea covered the area for six centuries ; since, it 

 had again been recovered from the sea, and Flemish towns built 

 on It. Without our attributing this to any sinking and elevation 

 of the land, we may find other causes might lead to such a state 



