492 KEY. A. IET1X& OX A GEXEEAL SECIIOX OF THE 



36. Gesteeal Section' of tJie Bagshot Steaia from Aldeeshot to 

 WoETN-GHAiT. Bv the Eev. A. Ietixg, B.Sc, B.A., T.G.S. 

 (Eead April 15, 1SS5.) 



A SEsroEN-CE of some years in the Bagshot distiict of the London 

 Basin has afforded me opportunities for many observations on the 

 Bagshot strata which have escaped the notice of previous writers 

 on the subject. Some of these have been already recorded *. Two 

 or three years ago I was led to investigate the origin of the green 

 colouring- matter so prevalent in the ACiddle and Lower Bagshot 

 strata, and an account of the results arrived at was given in the 

 * Geological Magazine ' t, the bearing of the facts upon the question 

 of water-supply being shown to be of some economic importance. 

 More recently i I have given some results obtained by a further 

 prosecution of the same line of inquiry, and have stated that they 

 have led me to regard the Middle and Lower Bagshot strata as, 

 upon the whole, a series of delta-, marsh-, and ?a(/oon-deposits, such 

 as are now forming in the alluvial flats at the mouth of many a 

 large river, but those of the Upper Bagshot as the deposits of a 

 marine estuary, which covered up and overlapped the Middle and 

 Lower series, so as to have extended over parts of the London 

 Clay. This inference from chemical and physical evidence is at 

 variance with the generally received view as to the physical history 

 of these strata, the first eminent worker on these beds having 

 declared that they were conformable to the London Clay §, and the 

 Geological Survey having mapped the district in accordance vdth 

 such a supposition. 



The main object of this paper is to bring before the Society 

 stratigraphical evidence on this question. It must be understood 

 that I make no attempt here to correlate the strata of our Bagshot 

 district in detail with the corresponding strata of the Hampshii'e 

 Basin : I use the terms ' Upper,' ' Middle,' and •' Lower,' therefore, as 

 apphed to the Bagshot strata, in thek natural sense, to mean the 

 well-marked upper, middle, and lower divisions of the latest Eocene 

 formation of the district to which it owes its name, regarding this as 

 a distinct area of deposition in Bagshot times. 



La the classification of the Bagshot beds I have included the bed 

 of loamy sand (So. 4, figs. 1 & 2), which occurs so generally imme- 

 diately above the green sands and clays, in the Middle Division (as 

 was done by the Survey) ; the pebble-bed, however, which commonly 



* See Proceedings of the Geologists' Association, vol. viii. pp. 143-173. 



t See Geol. Mag. dec. ti. vol. s. pp. 404-413. 



X Fcrid. dec. iii. vol. ii. 



§ See Prestwich, Quart. Journ. Geol. Soc. vol. iii. 



