XV11. 



the Reading beds, so-called from the locality where they are best 

 developed a clay deposit, with intercalated beds of sand and pebbles 

 outcropping in brick pits at East Cornard, East Bergholt, and Brent 

 Eleigh, along the valleys of the Stour and Brett, and in the neighbour- 

 hood of Ipswich at the Stoke, Trinity, and other brick-pits, and in a 

 chalk-pit one mile N. of Bramford Station. 



At Ipswich, in the bed of the river, are to be seen blocks of Grey- 

 wether sandstone (Sarsen stones), which belong to a bed of fine light 

 sand with pebbles, which constitutes the upper member of the Lower 

 London Tertiaries, or the Oldhaven beds. 



The London Clay, overlying the above, is best seen between- the 

 rivers Stour and Orwell i but it extends as far North as Orford, where 

 it is 170 feet thick, and the valley of the Fynn. It is to be seen 

 in various coast sections exposed at the base of the Red Crag, as at 

 Bawdsey. It is a bluish mud of marine origin, rich in iron, containing 

 in Suffolk few fossils except quantities of fish teeth and fossil wood, 

 impregnated with sulphide of iron. At the base is a sandy bed with 

 here and there a layer of flint pebbles. The mineral characters 

 are peculiar. Scattered through the clay, but more distinctly bed- 

 ded lower down, are concretionary nodules of argillaceo-calcareous 

 material, often veined with crystalline carbonate or sulphate of lime, 

 called septaria, occasionally containing impressions of fossils, which 

 were quarried for the manufacture of cement. Crystals of Selenite 

 (Calcic Sulphate) also occur the qongealed water of the quarry- 

 men. At Kypon Quay, near Woodbridge, in 1839, was exposed a 

 section of the lower beds, in which were found the teeth of Lamna, 

 and bones of Didelphys Colchesteri, H yracotherium cuniculum, and 

 Cheiroptera and other animal remains. Near Ipswich have been ob- 

 tained the fossil fruit of some palms, and quantities of fossil wood, the 

 latter being very abundant on the sea-coast from Felixstowe to Bawd- 

 sey. These, if properly prepared, will often shew cellular structure 

 when examined under the microscope ; and in some specimens, obtained 

 from the shores of the Deben, I have been able to make out very plainly 

 the bordered pits so charcteristic of the Coniferse. In some places the 

 wood is converted into calcite by a deposition of carbonate of lime, and 

 these under similar conditions will shew the perfect structure of the 

 plant when magnified. 



