LOWER GREENSAND. 377 



sandstones, 20 feet thick. They include Unio Stricklandi, Cyrefia 

 media, Palndina elongata, P. Sussexieitsis, etc. None of the marine 

 forms usual in Lower Greensand have been met with, and the 

 fossils are suggestive of Wealden beds. At Great Hazeley, and 

 other places south-east of Shotover, the beds rest on Portland 

 or Purbeck strata, while near Woburn the equivalent beds are 

 overlaid by Gault. Although distinct from the marine deposits of 

 Seend, Faringdon, etc., these beds are now usually regarded as an 

 estuarine deposit of Lower Greensand age.^ 



At Brill the Ironsand series (fifty or sixty feet) rests on the 

 Purbeck Beds, and comprises brown ferruginous sandstone, with 

 Cyrena, and white and yellow sands ; at Quainton, also, remains 

 of Cyclas and Paludina occur in the lower beds.- 



At Hartwell and Stone, near Aylesbury, the Purbeck Beds are 

 covered with brown ferruginous and white sand, with pebbles of 

 quartzite, quartz and lydian stone. The white sand of Hartwell 

 (eight feet) has been used for glass-making, and sent to Birming- 

 ham ; the lower beds contain hard siliceous concretions called 

 " Bowel-stones," used as ornaments in the neighbourhood. At the 

 base of the sands of Hartwell, according to Prof. Morris, but not 

 in situ, are blocks of compact brown sandstone, containing casts 

 of Unio, Cyrena, Paludina, and traces of Plants. The sands them- 

 selves contain impressions of Litna, Pecten, Exogyra sinicata, etc. 

 Near Stone, at the base of the sands, Unio and Paludina were also 

 met with, as well as Endogenites erosa, suggesting the former exis- 

 tence over this area of Wealden Beds, which were subsequently 

 removed by denudation, previous to or during the deposition of the 

 sands above.^ At Round-hill pit, near Stone, the sands are covered 

 by beds of impure fuller's earth and coarse iron-sandstone, con- 

 taining casts of Pecten, Ostrea, etc. In this neighbourhood the beds 

 yield a good water-supply. 



Woburn Sands, Potton and Wicken Beds. — The Lower Green- 

 sand is well exposed near Leighton Buzzard, at Little Brickhill in 

 Buckinghamshire, between Fenny Stratford and Woburn, at Sandy 

 and Potton, and at Wicken and Upware south-west of Soham. It 

 consists of iron-sands, etc., and contains near its base a variable 

 band of gravel or nodule-bed (6 in. to 2 feet in thickness) full of 

 fossils, mostly water-worn, including many bones and teeth of 

 Saurians, Fish-remains, and ' coprolites.' Pebbles of quartz, 

 quartzite, lydian stone, and ironstone occur in the bed, which is 

 sometimes cemented into a hard rock by carbonate of lime. Most 

 of the fossils are derived from the Wealden and Upper Oolitic 

 strata. Some indigenous fossils are found, and they indicate that 

 the beds are of the age of the Lower Greensand. Among derived 

 fossils, Ammonites biplex is very abundant. The indigenous fossils 



^ See Phillips, Geol. Oxford, p. in ; Q.J. xiv. 236, xvi. 309 ; Fitton, T. G. S. 

 (2), iv. 272 and plate xa. ; E. Hull, Explan. Sheet 13 (Geol. Survey), p. 15 ; see 

 also J. J. H. Teall, The Potton and Wicken Phosphatic Deposits, p. 32. 



"■* A. H. Green, Explan. Sheet 45 (Geol. Surv.), p. 50. 



2 G. Mag. 1867, p. 459. 



