Morris — Ferruginous Sands of Buckinghamshire. 459 



occupation of Britain. An account of these discoveries was commu- 

 nicated by Mr. Akerman to tlie Society of Antiquaries in 1851. 



These sands occupy a considerable area on the top of the hill near 

 Stone, being about one quarter of a mile from north to south, and 

 about three quarters of a mile from east to west. From their area, 

 their ready permeability to water (having been estimated to yield 

 about 40,000 gallons of water per day), and the geological condi- 

 tions of the underlying strata, they are important as an available 

 source of water-supply, the capabilities of which for that purpose 

 were first pointed out by Dr. Millar, F.Gr.S., in 1854, after the 

 failure of a well, 500 feet in depth, sunk in the Bucks Asylum 

 grounds, through the Portland and Kimmeridge beds into the Ox- 

 ford clay. Acting upon his suggestion, that this body of sand would 

 always contain a sufficient store of water, the Asylum has since 

 that time derived its chief supply from this source.^ 



During some excavations for drainage in the adjacent grounds at 

 a lower level, and probably corresponding to the base of the sands 

 at their junction with the Purbeck strata, masses of ferruginous 

 sandstone with JJmo and Paludina were fomid similar to those in 

 the red sand-pit. At nearly the same horizon, near Stone Church, 

 many specimens of Endogenites erosa were found by the Eev. Mr. 

 Lowdnes and myself, indicating, as I believe, the former existence of 

 the Wealden beds over this area, subsequently removed by denuda- 

 tion previous to or during the deposition of the sands above, and 

 disproving to some extent the notion that these sands are the 

 equivalents in time of the Wealden and Purbeck strata. 



Having shown that these sands, containing fossils of the Lower 

 Greensand, and at some points freshwater shells near their base, 

 sometimes overlie the Purbeck and Portland beds with an indication 

 of the Wealden, it may be interesting to trace the equivalent strata as 

 they range to the north-east or south-west of this district, and com- 

 pare the mineral character in different localities as given by various 

 authors.^ 



The sands trend north-westerly from Aylesbury, through Bedford 

 and Cambridge into Norfolk, where, under the name of " Carstone," 

 they underlie the red chalk and cretaceous beds, as is well seen at 

 Hunstanton. At Potton,^ in the former county, many fossils and 

 phosphatic nodules have been obtained, and at Wobum, in the same 

 formation, fuller's earth has long been worked.* 



At Upware, in Cambridgeshire, these beds have recently been 

 shown to be fossiliferous, containing many species of Terebratula 



^ Special report in reference to the supply of water for the Bucks Lunatic Asylum, 

 1856, p. 17. Mr. Prestwich remarks " that the effective permeable beds of the Lower 

 Greensand are 200 feet thick, that they occupy an area above and below ground of 

 4,600 square miles, that a mass of only one mile square and one foot thick will hold 

 more than 60,000,000 gallons of water, and some idea may be then formed of the 

 magnitude of such an underground reservoir." — "Water-bearing Strata," p. 179. 



2 Dr. Fitton, Geol. Trans., Vol. iv. p. 285, ef seq. Hollo way, Phil. Trans. 1723, 

 Vol. xxxii. p. 419. Prestwich, "Water Bearing Strata, p. 85. 



3 Seeley, Ann. and Mag. Nat. Hist., Aug. 1866. Walker, ibid., Aug. 1867. Brodie 

 Geol. Mag., Vol. IIL p. 153. 



* Conybeare and Phillips, Outlines, p. 138. Fitton, Geol. Trans., Vol. iv. p. 294. 



