Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/104

 down into their present places by successive transport from higher to lower levels during a long-continued fluviatile denudation — because such a successive and long- continued transport could not have failed to grind the smaller pebbles into sand, and to reduce the angular flints into all stages of wear, connecting them with the pebbles themselves.

In the map accompanying this paper, some of the more elevated gravels within the escarpments of the part of the Weald under consideration which are characterized by the presence of an admixture of chalk flints and Tertiary pebble, are shown in a way which distinguishes them from the rest of the gravels there. Of these, such as fall within the area drained by the Medway or its affluents, have been described by Messrs. Poster and Topley*. The rest, lying within the drainage-area of the Stour, I will briefly notice.

About Kennington, near Ashford, these occupy a high position, far above the Stour, and distant about a mile from it. The bulk of the Kennington gravel is composed of subcretaceous material ; but there is a considerable proportion of angular flint in it, and some Tertiary pebble.

On the opposite side of the Stour, at Willesboro', is a remarkable patch exposed in the road-cutting west of the village. So far as I could detect, upon a brief examination, this gravel, 5 feet thick, was almost entirely made up of Lower-Tertiary pebbles and fragments of flint. At Smeeth, three miles further west, and midway between Merstham Hatch and Ridgeway, there is a gravel of subcretaceous material, intermingled with flint and Tertiary pebbles and a few pieces of chalk ; and over the gault belt near to the chalk escarpment, angular white-coated flints often occur lying on the surface, but apparently no Tertiary pebbles.

The position of these gravels near Ashford, and of those above Maidstone, relatively to the chalk escarpments near each place, and to the rivers Stour and Medway, is indicated by the Sections A and B that accompany the map ; and the Sections have their places indicated by lines upon the map. In both cases these gravels he near what I regard as river-mouths bringing in drainage from the north ; while similar gravels, described by Messrs. Poster and Topley, lie within the Medway area on the Weald clay beneath the Lower Greensand escarpment, and occupy a position near what I regard as one of these river-mouths after it had advanced from the Chalk escarpment at Maidstone to the Lower-Greensand one near Yalding.

In the case of some of the gravels near Maidstone, Messrs. Topley and Foster offer, as the explanation of the occurrence of flints, nodules of chalk, and pebbles in them, the action of a rivulet tributary to the Medway, which runs up towards the foot of the Chalk escarpment at Boxley. But though angular flints and chalk might by such a means find their way into the Medway, it is not apparent how Lower-Tertiary pebbles could do so, even at the greatly higher level at which both the tributary and the Medway itself must have flowed to reach the high situation of these gravels at Banning, and above Allington (near Maidstone).

The position of the gravel at Willesboro' is still more antagonistic —


 * Loc. cit.