CLAYGATE BEDS. 31 



Brickearth.' Claygate Beds are also preserved at Stanmore 

 beneath the gravel, at- High wood Hill and elsewhere in North 

 Middlesex. 



In the south-east Claygate Beds occur on the Crystal Palace 

 Hill, where sections formerly visible have been described by 

 Mr. Whitaker. 1 Shooters Hill appears to lie in a slight synclinal 

 fold, and the Claygate Beds may be 60 ft. thick. They have 

 been described by Mr. A. L. Leach. 2 



In Essex the 6-inch -survey has yet to be made, and the 

 Claygate Beds have not been mapped. They occur wherever 

 the Bagshot Sands are shown and on certain hills where those 

 beds are no longer preserved. 



West of the Roding they have been noticed near the 

 Obelisk in Hawk Wood, at High Beech 3 and Loughton Camp, 4 

 and have been described in detail at Oakhill Quarry on the 

 northern margin of the map. 5 The boxstones with casts of 

 fossils are mentioned. 



At South Weald 46 ft. of Claygate Beds were proved in a 

 boring at the Essex County Asylum ; another in High Street, 

 Brentwood, on the margin of the map shows 41 ft. of Bagshot 

 Sands, 92 ft. of Claygate Beds and 390 ft. of London Clay. 6 

 The Passage Beds are mentioned by Mr. Monckton 7 and also by 

 H. B. Woodward, who estimates their general thickness round 

 Brentwood as 50 ft. 8 



As mentioned above the Claygate Beds are present beneath 

 the Thames gravels around Laleham and Littleton, on the axis 

 of the London Basin syncline. To the west of our map, about 

 the longitude of Windsor the beds die out, their place being 

 taken by a slight unconformity or non-sequence. 



BAGSHOT SERIES. 

 BAGSHOT, BRACKLESHAM AND BARTON BEDS. 



The strata immediately succeeding the Claygate Beds comprise 

 a series of sands, clays and pebble-beds, which have been grouped 

 into Lower and Upper Bagshot Sand with an intermediate division 

 of Bracklesham Beds. 



It is now recognized that the Upper Bagshot Sand, which is 

 developed to the west and south of Chertsey, at Bagshot Heath 

 and other parts of Surrey, and in Berkshire and northern Hamp- 

 shire, is to be correlated with the Barton Beds of southern 

 Hampshire. In consequence the term Bagshot Beds is restricted 

 to the lower division, and the Upper Bagshot Sand is now included 

 with the Barton Beds. 



L Op. cit., p. 243. 



2 Proc. Geol. Assoc., vol. xxiii, 1912, pp. 112-118 ; vol. xxiv, 1913, pp. 115-117. 



3 Proc. Geol. Assoc., vol. xiv, 1896, pp. 337, 338. 



4 ' Geology of London ' (Mem. Geol. Surv.), vol. i, 1889, p. 258. 



5 Robarts, N. F., ' London Clay and Bagshot Beds in Epping Forest,' Trans. 

 Essex Field Club, vol. iii, 1883, pp. 231-236. 



1 * Water Supply of Essex ' (Mem. Geol. Surv.), 1916, pp, 104, 105. 



7 Proc. Geol. Assoc., vol. xi, 1889, pp. Ixii-lxiii. 



8 In ' Geology of London ' (Mem. Geol. Surv.), vol. i, 1889, p. 274. 



x 17412 B 3 



