II J. — On the Bagshot Sand. 



By henry WARBURTON, Esq. v.p.g.s. 



[Read June 15, 1821.] 



J. AM not aware that the sand of Bagshot Heath has yet been described with 

 such attention to detail^ and reference to locahties^ as will enable an inquirer 

 to form a correct opinion concerning its geological character. Mr. Smith 

 indeed is stated, in Mr. Farcy's Survey of Derbyshire, to have ascertained 

 that it is the highest known stratum in England, and that it rests upon the 

 clay of London ; but no proofs of this statement are there given, and I do 

 not find a repetition of it in the memoir that accompanies Mr. Smith's geolo- 

 gical map; nor is the map coloured in conformity with this opinion. 



Concerning the Bagshot sand it may be asked, whether, hke the gravel 

 about London, it consists of diluvian debris, or whether it belongs to a regu- 

 lar stratum, like the sands of the plastic clay } and admitting it to belong to a 

 regular stratum, it will be a question to what position we shall refer it among 

 the beds superior to the chalk. 



The sand of Bagshot Heath occupies a district extending from east to west, 

 along the axis of that great depression in the chalk which has been called the 

 London Basin. The length of this district, from its eastern extremity at Esher 

 in the county of Surry to its western extremity at Bromshill Common on the 

 confines of Berkshire and Hampshire, is about twenty-five miles. From Hun- 

 gry Hill near Farnham to Oakingham, where its breadth from south to north 

 is the greatest, the distance is about twelve miles ; but its average breadth is 

 considerably less. The course of its southern boundary is marked by those 

 sandy elevations, which beginning at Esher extend to Claremont, Painshill, 

 Breach Hill, and Ockham Hill near Ripley. After crossing the river Wey, the 

 sand (thinly spread over the stratum which it covers) may be traced across the 

 plain through which the Basingstoke canal passes. Purford Heath and a 

 series of low commons mark its course to Romping Downs and Gravelpit Hill, 

 about seven miles north-east of Farnham, where it again rises into consider- 

 able acclivities. At Tuksbury Hill and Beacon Hill Camp, immediately north 



