London 



Clay. 



404 Rev. A. Irving — The Bagshot Beds and London Clay. 



feet. 

 Soil and clay (brown) 3 



f Lead-coloured, hard, flaky clay ... ... ... ... 20 



Keddish sand and lead-coloured clay ... ... ... 80 



Lead-coloured, strong loam ... ... ... ... 60 



Lead-coloured clay or loam, with stony nodules (septaria) 40 



^ Hard rock | 



Lead-coloured clay with much sulphur, many lumps of 

 stone, giving off ' ' noxious air," some rotten wood 



below 236 



^Hardrock \ 



Total thickness of London Clay 437 



440 ft. 

 This well was " sunk all the way." 



At page 282 of the Memoir, Mr. Whitaker mentions a section in 

 the Wimbledon neighbourhood, which shows a passage upwards- 

 from the London Clay into Bagshot Sands. This bears out the 

 inference which I drew in my last paper from lithological evidence 

 very similar to that cited by him, as to such a passage occurring in 

 the well-section at Brookwood. 



It is of course a rare thing in wells in these Tertiary strata 

 to come across a shoal of fossils, such as that mentioned by me h 

 elsewhere, as occurring in the green earthy sand of the Middle 

 Bagshots at Yateley, Hants ; but isolated fossils are occasionally met 

 with, and generally, as might be expected, in a good state of 

 preservation in the London Clay. In the deep well at the Ascot 

 Bacecourse, of which I have already published an account, 2 the 

 following, which are now in my possession, were found : Plwlodomya 

 margaritacea (192 above the base) ; Cyprina plana to, (a rather young 

 individual). A well-rounded pebble of flint was also found at 

 75 feet above the base of the London Clay. 



Prof. T. Bupert Jones, F.K.S., 3 has also mentioned the following 

 as met with in the Wokingham deep well : Cardium, Cyprina planata, 

 Pholodomya virgulosa, Nautilus, Panopcea intermedia, Pinna (fragment), 

 p/entalium, Actceon, Natica, Astarte, Cytherea tenuissima, Ditrupa. 

 These forms range through the whole of the 273 feet of the London 

 Clay pierced in that section, including the Basement Bed. 



From Mr. Phillips's brick-yard, close by Wokingham Station, and a 

 few feet only below the unconformable junction of the Bagshot Sands 

 and the London Clay, which is seen just below St. Paul's Church, 4 1 

 have obtained the following forms : Cyprcea BoiverbanTcii, CardiumLay- 

 toni, Corbula Begulbiensis (?), Modiola elegans, Panopcea (fragment), 

 Pleurotoma gentilis, Vermicularia Bognoriensis. Some of the septaria 

 found in this pit are charnel-houses of scarcely any other forms than 

 V. Bognoriensis. The presence of these forms would seem again to indi- 

 cate a tolerably low horizon in the London Clay for the beds on which 

 the Bagshot Sands at Wokingham are superimposed. Oxidation-pro- 

 ducts of pyrites and flint pebbles are common in the London Clay here- 



1 QJ.G.S. August, 1885, p. 500. 2 Proc. Geol. Assoc, vol. is. No. 5. 



3 Geol. Mag. Decade II. Vol. VII. pp. 422, 423. 



4 QJ.G.S. loc. cit. p. 505, fig. 4. 



