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PROCEEDINGS OE THE GEOLOGICAL SOCIETY. 



[Mar. 6, 



the sand's, without reaching to their base ; for the lowest beds seen 

 (those at Crowborough Mills seem to be so) are of just the same 

 sort of sandstone and loam. Some miles north and north-east of this 

 there are other tracts of this sand, of very irregular forms ; they are 

 brought to the surface by one or more anticlinals that run somewhat 

 east and west. There are two inliers* of it quite near to the 

 country of the Weald Clay itself; namely, one a few miles to the 

 south-east of Edenbridge, and another that stretches from Penshurst 

 to beyond the line of railway between Tunbridge and Tunbridge 

 Wells. 



A. Presence of the Ashdown Sand in the Railway-section from 

 Tunbridge to Tunbridge Wells, and the Extent of the Tunbridge Wells 

 Sand to the northward. — It is just at this part that the beds were 

 examined by Mr. Morris and Mr. Prestwich, whose description of 

 them is printed in the Society's Journal f. In making a comparison 

 of this with the results of my own observations, I must refer you 

 to the transverse section, fig. 2, p. 276. Mr. Morris and Mr. 

 Prestwich began their observations by the Tunbridge Tunnel ; and 

 just on the south of it they saw sandstone beds coming from under- 

 neath a great thickness of clay and shale. Passing on through seve- 

 ral cuttings, and rightly interpreting a fault (the throw of which, 

 however, they somewhat overrated), they came to shale again, this 

 time overlain by sandstone. This, however, they take to be a lower 

 bed of shale (partly from its differing from the other in being unfos- 

 siliferous), and they consider this sandstone, which continues on to 

 Tunbridge Wells, to be in the same part of the series with that they 

 first saw, accounting for the position of the shale by supposing a 

 second fault, concealed in the valley. I am, however, convinced 

 (and I have no doubt that Mr. Prestwich and Mr. Morris would have 

 come to the same conclusion if they had been able to extend their 

 observations for a few miles to the east and west of the railway) that 

 these last shales, coming from underneath the Tunbridge Wells Sand, 

 are the upper part of the bed of which the shales at the Powder-mill 

 and Tunbridge cuttings are the lower (namely the Wadhurst Clay), 

 and that the sandstone underneath them at the lat ter places is the top 

 of the Ashdown Sand. This I have proved by tracing the shale around 

 this inlier of sand which I observe to come from underneath it ; while 

 the shale, in its turn, is covered by the mass of sand from Bidborough 

 to Tunbridge Wells, as well as by like sand on the other side of the 

 valley, and is capped by two or three outliers of sand nearer to Tun- 

 bridge. The difficulty in the way of this explanation, which they 



* I doubt if this word inlier is enough in use to be allowed to pass without 

 explanation ; for I have never seen it in print. It means a space occupied by one 

 formation which is completely surrounded by another that rests upon it. It is 

 useful to have a word that will express this ; and " inlier " is a very appropriate 

 one ; for the circumstance to be named is the exact converse of " outlier," which 

 is an isolated mass surrounded by a formation that underlies it ; and the advan- 

 tages of '• inlier" are manifest over such a phrase as was used in the same sense 

 by the late Mr. P. J. Martin, namely, "outlier by protrusion." 

 ' t Quart. Journ. Geol. Soc, No. 8, vol. ii. p. 397. 



