DR. HENRY WOODWARD ON EAST ANGLIAN GEOLOGY. 489 
At Culford boring, Chalk 526 ft. ; Gault 73 ft. ; Lower Green- 
sand 32 ft. 6 in. = 631 ft. 6 in. 
The Kent Coal Exploration. 
At Brabourn, Palaeozoic rocks were reached, but no coal. 
At Dover, 15 m. to the E. of Brabourn, coal was found ! 
Beds above the Chalk. 
Overlying the Chalk we come to the Tertiary Series. 
(1) “Woolwich and Reading Beds” have been observed at 
Sudbury, and in well-borings at Woodbridge, Saxmundham, and 
perhaps at Iloxne. Prestwich records them in a well at Yarmouth, 
46 feet thick, 310 feet of London Clay, and 170 feet of newer 
deposits. These Eocene beds are probably present above the Chalk 
to the east of Surlingham and Wroxham in Norfolk. 
(2) “London Clay.” This formation was so named by 
William Smith in 1812, from its development around London. 
It consists of a stilf brown and bluish Clay, containing layers of 
septaria or cement-stones which mark the lines of stratification. 
There is a green and yellow sandy and loamy bed at its base, con- 
taining flint- pebbles, sometimes cemented by carbonate of lime into 
semi-concretionary tabular masses. The top strata are also sandy, 
passing in places into the lower Bagshot Beds above ; much used 
for brick-making , but the bricks are of a bad colour. 
The London Clay contains much iron-pyrites and selenite, due 
to the decomposition of iron-pyrites and the destruction of organic 
remains ; the SO ;i from the pyrites uniting with CaCO s of the fossils 
forms selenite. The thickness of the London Clay varies from 
50 to 60 feet in Berks, to 500 in S. Essex, often with abundant 
fossils. The London Clay extends over N. Kent, Surrey, Berks, 
Middlesex, Herts, and Essex, and the borders of Suffolk to Yarmouth. 
The fossils of the London Clay, eroded and often partly coated by 
or enclosed in phosphatic nodules, occur at the base of the Suffolk 
Crag at Felixstowe and elsewhere, and include the teeth of land 
animals ; also Crustacea and the teeth of Sharks. Those of Ctielonice 
are frequently obtained in the Septaria dredged up off the mouth 
of the Orwell at Harwich. 
