BAGSHOT SERIES. 35 



seen in a large pit on Oxshott Heath (now a public common). In this 

 pit the sands are buff-coloured, and contain streaks of grey and rather 

 clayey sand; they are capped by Plateau Gravel. Two outliers of 

 Bagshot Beds between Claygate and Chessington are also marked on 

 the map. Another tract of basement Bagshot Beds, not shown on the 

 map, has been proved in the brickyard north-east of Claygate Station, 

 between South Hill House and Cooper's Hill. 



The sections on the railway between Walton and Weybridge were 

 described in detail by W. H. Hudleston, 1 but his ' Bagshot Beds ' include 

 much that is now called Claygate Beds. At the western end of tha 

 cutting, by Weybridge Station, a section still open shows 25 ft. of typical 

 Bagshot Sands, belonging to the middle part of the group. In the 

 Brooklands Motor Track there are many sections of the Bagshot Sand; 

 at the north-west corner of Canes Wood, H. B. Woodward noted the 

 following details : 



Ft. 

 False-bedded ochreous sand, with irregular and imper- 



sistent clay-seams about 20 



Grey clayey sand with ochreous nodules - 10 



Pale clayey sand - - 5 to 10 



Grey sand, ferruginous at base - 15 



Grey and brown sandy clay, throwing out springs 

 [ ? Claygate Beds] - seen to 8 



On St. George's Hill the whole series, Bagshot, Bracklesham and 

 Barton Beds, may be studied. Most of the sections in the Firgrove 

 Brickyard, described by Woodward 2 have been obscured by the progress 

 of building. The sandpit, however, is still (1919) untouched and shows 

 the top part of the Bagshot Sand and the base of the Bracklesham Clays. 

 The sands are seen to be clearly stratified in horizontal layers, often only 

 a quarter of an inch thick, but individual layers are minutely current- 

 bedded ; many seams of pipe-clay are interstratified with the sands. In 

 parts of the section the colouring is very brilliant, the sands being deep 

 pink, yellow and silver-white, while the pipe-clay is crimson, grey or 

 white, recalling the famous sands of the same age at Alum Bay. The 

 Bracklesham Clays occupy a basin cut in the sands across the bedding ; 

 they are lilac-grey in colour, and somewhat laminated, developing a 

 prismatic structure on weathering. Both the sands and the clays show 

 staining by iron, but at the contact of the two materials the iron is 

 segregated to form an ironstone. This ironstone was, at one time, 

 extensively worked by means of shallow trenches, which follow the 

 junction nearly all round the hill, and afford a useful guide in mapping. 

 The ore was smelted and wrought at a mill, now known as Ham Mill 

 on the Wey. Dr. Eric Gardner, of Weybridge, has traced the history of 

 this industry and tells us that it was in existence more than one hundred 

 years, from 1710 to 1812. On the original one-inch Geological Map of 

 the district, of which the topography is dated 1815, the site of the works 

 is still marked as ' Iron Mills.' A picked specimen of the ironstone was 

 analysed at the Survey Laboratory and found to contain only 23 per 

 cent, metallic iron. 3 



No other instance is definitely known of the use of a Tertiary 

 ironstone in the London Basin. A photograph of this pit is given in 

 the Windsor Memoir (Plate IV.). Another section on the south side of 

 the hill shows the Bracklesham Clays resting horizontally on Bagshot 

 Sands; but the overlying green beds are nowhere well exposed. The 

 outcrop of the Barton Sands forms a narrow fringe round the greater 

 part of the gravel-cap, as shown on the new map (Sheet 269). The sands 



1 Quart. Journ. GeoL Soc. y vol. xlii, 1886, pp. 147-172; vol. xliii, 1887, 

 pp. 443-456. 



2 Proc. GeoL Assoc., vol. xxii, 1911, pp 237-240. 



3 Bromehead. C. N., Proc. GeoL Assoc., vol. xxx, 1919, p. 127. 



