﻿274 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 6, 



The boundary between it and the first stratum of the Hastings Sand 

 is sharply defined : in many places, as at the river-bank below Ram- 

 hurst Farm near Tunbridge, at Capel on the east of that town, and 

 at Culverden Quarry and Rusthall Common, both near Tunbridge 

 Wells, the clay is seen to rest immediately on good sand or sandstone. 

 At a certain height, however — perhaps thirty feet — above the junc- 

 tion there is a layer of loam with a little sandstone, which may vary 

 from twenty to a very few feet in thickness. This is within what I call 

 " Weald Clay." Between this layer and the stratum-level that I 

 take for the boundary, is stiff clay or shale, sometimes containing 

 lenses of calcareous grit *. 



2. Tunbridge Wells Sand. — The first layer of the Hastings Sand 

 I call " Tunbridge Wells Sand" ; and in using this and other names 

 of my adoption I have been guided by reasons which will best be 

 given towards the end of this paper. 



The top of the Tunbridge Wells Sand is hardly seen on the first 

 outcrop of it from beneath the Weald Clay, though at these points — 

 namely, on the left bank of the Medway on the west, and by Sandlin 

 and Capel -bank on the east of Tunbridge — there are moderately good 

 sections ; but it is well shown in several parts of that great spread 

 of this subdivision which occurs all around Tunbridge Wells. The 

 top bed is in many places a fine, hard, white sand, with few or no 

 partings or distinction of beds in it, similar in composition to that 

 thick bed of sand underneath the Castle and in the East Cliff at 

 Hastings, though this belongs to another horizon. It is stuff that is 

 difficult to work out, and sometimes requires even blasting; but 

 when separated into fragments, a touch will break it into loose sand. 

 In other places the bed is a soft, generally buff-coloured, or else 

 light-brown building- stone in a massive bed. The gradual change 

 from the first kind of substance (which may conveniently be called 

 " rock-sand ") to the other is well seen along two or three different 

 lines — namely, from Tunbridge Wells by Rusthall Common to Lang- 

 ton t, from the High Rocks to the summit of Groombridge Hill, and 

 from Eridge Rocks to Alksford and Sherlock's. I have measured at 

 different places 25, 35, and even 48 feet of the rock-sand, and of the 

 equivalent bed when sandstone 10, 12, or 16 feet, generally in one 

 thick, pretty hard layer. Beneath this well-marked top bed come 

 still sandy beds, but not massive ones like the first ; for the greater 

 part of the Tunbridge Wells Sand may be described as soft, buff or 

 light-brown sandstone in beds of half a foot, 1, 2, 3, or more feet 

 thick, interstratified with beds of loam, thin beds of clay, and now 

 and then some rather loose sand. The whole thickness of the subdivi- 

 sion seems to be 160 or 180 feet. I judge it to be as much as this 



is a general dip to the north (in one or two places I have seen the beds dipping 

 in that direction) ; if it were only half or three-quarters of a degree, the thickness 

 would be GOO feet, I am indebted to Mr. Bensted, of Maidstone, for the infor- 

 mation about the borings. 



* In the following localities : — River-bank nearly a mile east of Leigh ; rail- 

 way-cutting north of Penshurst Park ; near Fordcombe, &c. 



t Marked Lengthington Green on the Ordnance Map. 



