UPPER GREENSAND. 387 



and sometimes marshy tract ; but in many places oaks grow well upon it. (See 

 P- 3^3-) The beds are much used in the manufacture of bricks and tiles. 

 There are large brickyards at Cambridge, at Arlesey, south of Biggleswade ; also 

 at Aylesford and Burham in Kent. The Burham bricks are white. At Chipstead, 

 north-west of Sevenoaks, Gault and overlying Pleistocene brickearth are worked 

 for brick-making. At Folkestone, Portland cement is manufactured from Gault 

 clay mixed with finely levigated Chalk. Coprolites have been worked at Towersey. 



TIPPER GREENSAND. 



The Upper Greensand consists of greenish-grey sand and sand- 

 stone, the typical green beds generally being charged with 

 glauconite (hydrous silicate of iron, alumina, and potash) ; pale 

 calcareous sandstone and chert also occur. 



The term Greensand was used by William Smith in 1812, and was originally 

 applied to the sands overlying the Gault (Blue Marl). Later on the sands below 

 the Gault came to be termed Greensand, and much confusion resulted. The term 

 Upper Greensand was used by Murchison in 1825. The terms Firestone and 

 Malm Rock have in old times been applied to this Greensand, from the local use 

 of the prominent beds of pale calcareous sandstone : the firestone being developed 

 at Merstham and Reigate, and the malm rock in West Surrey, Hants and Sussex. 

 These beds appear to represent one another, but the malm rock has a more chalky 

 appearance. The term Chloritic Sands, suggested by Godwin-Austen and adopted 

 by Lyell, is open to objections on the grounds that the term merely indicates a 

 colour which is far from predominant ; and that the green beds are charged with 

 glauconite (not chlorite). It was shown by Ehrenberg, and more recently by 

 Carpenter, that the green grains are very frequently internal casts of the chambers 

 of Foraminifera in glauconite. '^ 



The thickness of the Upper Greensand is about 60 feet on the 

 average in the Wealden district. At Petersfield it is 80 feet, at 

 Eastbourne 40 feet, at Godalming 50 feet, and at Wallingford 

 70 feet. 



The Upper Greensand contains the Echinoderms Discoidca 

 {Galenles) subuculus (' Button stone'), Salenia, Goniaster, Hctniaster, 

 Cardiaster suborbicularis, Psetidodiadema, etc. ; Mollusca, Pecten 

 { Janira) qiiinqnecoslatus, P. quadn'cosiahis, P. asper, P. orbicularis, 

 Cardium Hillanuvi, Exogyra conica, E. columba, E. {GrvphcFa) 

 vesiculosa, Ostrea frons {carinata), Plicafula inflata, Trigonia alccfonnis. 

 Ammonites varians, A. rostratiis; Brachiopoda, i?/y';/(://£i«(?//cz Grasiatia, 

 P. latissima, Terebratella pcctita, Terebratula biplicata ; Annelides, 

 Verniicularia concava ; Corals, Micrabacia corotiula ; and Sponges. 

 Siphonia and other Sponges are met with particularly in the 

 beds at Warminster and Blackdown, while at the Blackdown and 

 Haldon Hills and other localities, some beds are largely made 

 up of the detached spicular remains of siliceous sponges.- Teeth 

 of Fishes and bones of Saurians also occur. 



1 Q.J. vi. 470. 



2 Dr. G. J. Hinde, Phil. Trans. 1885, p. 403, Ann. Nat. Hist. (5), x. 1S5 ; E. 

 Parfitt, Trans, Devon Assoc. 1870; H.J. Carter, Ann. Nat. Hist. (4), vii. 



