. GEOLOGY 



Sands of Kent cannot be traced into Sussex. The earliest Eocene strata 

 preserved in the county are the highly variable estuarine deposits known 

 as the Woolwich and Reading Series. These show a complete change 

 of conditions, and contain animals and plants so different from those of 

 the Chalk that comparison is almost impossible. The formation now 

 stretches from the western border of the county in narrow belts through 

 Chichester and Arundel to Bognor, Worthing and Lancing, and is con- 

 tinued eastward by a chain of outliers at Portslade, Brighton, Newhaven 

 and Seaford. Originally however it must have overspread the whole 

 county, for it corresponds closely with the deposits of the Thames basin 

 and of the north of France. In the western half of the county the 

 strata are of the ' Reading ' type, i.e. they consist mainly of red-mottled 

 plastic or pottery clay, with occasional seams of lignite, flint pebbles and 

 sand, and with a bed of unworn green-coated flints at the base. These 

 deposits seem to be of lagoon or estuarine origin, though determinable 

 fossils have not yet been found in them in Sussex. The eastern half of 

 the county shows deposits more like the ' Woolwich ' type. At Lancing 

 beneath or near the base of the red-mottled clay occurs a band of iron- 

 stone with marine fossils. At Portslade we find a mass of bluish-black 

 shaly clays with a mixture of marine and freshwater fossils, principally 

 oysters and Cyrena. At Brighton the thin outliers towards Preston yield 

 moulds of marine fossils in ironstone, as well as traces of plants. New- 

 haven was formerly celebrated for its plant-beds, though these are now 

 either washed away or hidden by the sloping of the cliffs under the fort ; 

 the deposits there consisted mainly of laminated shelly or plant-bearing 

 clays, with seams of sand and masses of lignite, to a thickness of 60 

 feet. Red-mottled plastic clays are absent. The shells recorded by 

 Prestwich ' are mainly estuarine and freshwater species such as Dreissena, 

 Unio, Cyrena, Cerithium, Melanin inquinata and Ostrea bellovacina. The 

 flora is an interesting one, for it shows warm-temperate conditions, and 

 the plants are closely allied to species still living in warmer regions. 

 Unfortunately they are still only partially examined and described ; but 

 according to Mr. J. S. Gardner the greater part of the leaves belong to a 

 few species, amongst them being a palm and an aralia-like leaf. The 

 Woolwich and Reading Series is from 90 to 130 feet thick ; but occu- 

 pies so small an area in Sussex, and is so largely hidden by newer 

 deposits, that it has had little influence on the position of settlements, 

 except where the distruction of its outliers has overspread the Chalk 

 with the sheet of clay known as ' Clay with Flints.' This last-mentioned 

 deposit is often stated to be the insoluble residue of the Chalk dissolved 

 by falling rain. Such however cannot be the case, for it has a curiously 

 partial distribution, and only caps plateaus formerly overspread by Eocene 

 strata. Its composition also shows it to be formed mainly of recognizable 

 Eocene material, such as quartz sand, flint and quartz pebbles, green- 



1 'On the Structure of the Strata between the London Clay and the Chalk in the London and 

 Hampshire Tertiary Systems : Part IL — The Woolwich and Reading Series,' Qunrt. Joiini. Geo/. Soc. 

 X. 83-4 (18S+). 



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