WOOLWICH AND READING BEDS. 43 1 



at the base of the shelly clays there is generally a bed of imperfect lignite, and 

 lower down sometimes a pebble-bed. 



C. In East Kent we find the simplest state of this formation, which there 

 consists throughout of sharp light-coloured and false-bedded sand with marine 

 fossils, differing alike from the estuarine Woolwich Beds and the changeful 

 Reading Beds. One part of the formation is fairly constant. Where it rests on 

 the Thanet Beds, this lowest member of the Woolwich and Reading Series is a 

 greensand, more or less clayey, with flint-pebbles and here and there oyster-shells. 

 Where, however, it rests on the Chalk, it is usually of a more clayey character ; 

 the flints at its base are angular and green-coated, instead of being in the state of 

 perfectly rolled pebbles ; as before, there are sometimes oyster-shells in the green- 

 sand, and besides there are (somewhat rarely) casts and impressions of other 

 shells in the accompanying roughly laminated grey clays (with green grains). 

 The difference in the condition of the flints in the two cases is just what one 

 would expect : in the latter they have been derived directly from the underlying 

 Chalk, whilst in the former they must have been carried some distance, and 

 therefore worn. The estuarine Woolwich Beds also occur at Newhaven in Sussex. ^ 



The beds are poorly represented near Hertford, where they rest 

 directly on the Chalk. Thence they occur at Bishop's Stortford, by 

 Elsenham, near Shalford, Castle Hedingham to Middleton near 

 Sudbury, and Bramford (18 feet); and, according to Mr. W. H. 

 Dalton, they may be traced in well-borings at Woodbridge, 

 Saxmundham, and possibly at Hoxne.^ Prof. Prestwich determined 

 their presence in a well at Yarmouth, and there 46 feet of these 

 beds and 310 feet of London Clay were found beneath 170 

 feet of newer deposits.^ Eocene beds therefore are probably 

 present above the Chalk to the east of Surlingham and Wroxham, 

 in Norfolk. 



The Hertfordshire pudding-stone is composed of flint pebbles of various colours, 

 black, yellow and brown, embedded in a siliceous matrix, and so firmly cemented 

 that the pebbles are fractured equally with the matrix, along joint-planes. This 

 bed, which occurs near the base of the Woolwich and Reading series, has been 

 exposed in pits near New Organ Hall, Radlett, also at North Minis churchyard 

 and in ploughed fields to the north-east of that village.* Many specimens 

 have been procured from the Drift deposits of the eastern counties. 



The ' Bottom-bed ' of the Woolwich and Reading Series is described by Mr. 

 Whitaker as a roughly laminated dark grey clay and clayey sand, generally with 

 green grains ; it is often termed the Oyster-bed from the abundance in it of Ostrea 

 Bellovacina.° It sometimes includes an overlying and underlying shell-bed with 

 Cyrena, making the total thickness from 6 to 8 feet. This bed may be seen resting 

 on the Chalk, at Castle Hill, Coley Hill pits, and Katesgrove pit, near Reading, 

 also near Newbury, Pebble Hill near Kintbury, Hungerford, at Bromley, and 

 Charlton. 



The fossils of the Woolwich and Reading Beds comprise Mammals, 

 Birds, Reptiles, Fishes, Mollusca, Polyzoa, Crustacea (including 

 Ostracoda), Sponges, Foraminifera, and Plants. They indicate 

 marine, estuarine, and freshwater conditions. 



The Tapir-like Coryphodon has been met with in these strata, also 

 Turtles among the Reptiles. Gastornis Klaasseni was obtained by 



^ Prestwich, Q. J. x. 83 ; Whitaker, ibid, xxvii. 265. 



2 Geol. Mag. 18S0, p. 518; Whitaker, Geol. Ipswich, p. 14. 



3 Q. J. xvi. 449. 



* Whitaker, Mem. Geol. Survey, iv. 224 ; J. Hopkinson, P. Geol. Assoc, viii. 

 452 ; see also Buckland, T. G. S. iv. 301. 



* Geologist, iii. 390. 



