GEOLOGY Of similar character is the broad flat of Romney Marsh, which Hke the marshes of the Thames lies below the level of high spring tides. It is fringed along the greater part of its seaward margin by an accumula- tion of recent shingle, arranged in ' fulls ' or ' storm beaches,' and by sand dunes ; and where these are wanting the marsh is protected from the sea by artificial embankments. Within the marsh, marine sand and shingle is generally found at a depth of from lo to 20 feet, but this is overlain by clay and peat with trunks of trees. Great changes have taken place within the recent period in this tract both in the shape of the coast line and in the course of the river Rother across the marsh, but as these will be dealt with by the historian, passing reference to them will here suffice.' The great shingle spit at Dunge Ness, where the accumulated ' storm beach ' is two or three miles wide, is known to be growing out eastward at a rate estimated at about six yards annually, through the steady transference of the shingle in that direction. Meanwhile on the coast of the marsh to the westward the sea is encroaching, so that the position and shape of the Ness is constantly undergoing modification, and is known to have been quite diffisrent a few centuries ago. Being concentrated upon a narrow shore-line, the effisct of the sea upon the land is always more obvious than the subtle all-pervading influence of the atmospheric agencies. It seems scarcely necessary to mention that every part of the Kentish coast, except where artificially protected, is undergoing change, though nowhere so rapidly as at Dunge Ness. Its cliffs are being sapped and torn away piecemeal — rapidly where composed of soft material, as at Sheppey and Reculvers ; and more slowly, but still not very slowly, where of firmer build, as in Thanet and the South Foreland ; while its shallow estuaries are being gradually silted up and its salt marshes converted into firm land. DEEP-SEATED ROCKS Having deciphered the later portion of the geological history of the county, from the records contained in the structure of the present surface, and having thereby incidentally made easier the reading of such evidence as we may possess regarding the rocks which do not appear at the surface, we will now turn back to the earlier chapters of the history and consider the deep foundation of the county. As mentioned at the beginning of this article, very important additions have been recently made to our knowledge on this subject by the numerous deep borings which have been sunk in search of coal. Though the information as yet published regarding these borings is somewhat limited, it enables us to add very considerably to the list of formations recognized in Kent, and to prove the existence of a down- ward succession reaching to the base of the Secondary or Mesozoic rocks and even including part of the Palaeozoics.
- Consult Mem. Geo/. Survey, 'Geology of the Weald,' chap. xvii. p. 302, for geological account
of these changes. I 25 4
