THE ENVIRONMENT

The London Clay, Lower Eocene, was deposited in a well-oxygenated, low-energy, middle-shelf environment. The extent of the sea was probably similar to the present North Sea but closed to the Atlantic to the north. There was a connection to the south-west that opened within London Clay times and probably closed during the succeeding Bracklesham Beds. The water depth is estimated to have varied between 20 and 100 metres (King 1984). This is supported by the presence of sharks and teleosts not encountered in the shallower Tertiary waters and whose living relatives are restricted to relatively deep water. The abundance and nature of vegetable debris suggests an active river system, probably to the west, draining a tropical to sub-tropical rain forest. The mixture of plant genera with different (Recent) climatic requirements suggest an environment with no modern equivalent (Collinson 1983: 24). Fringing the coast there was probably a swamp similar to those present in parts of Indonesia and Malaysia. This reconstruction is supported by the abundance of Nipa fruits and species allied to the mangroves. The mean daytime temperature is estimated to be 22-25C. A description of the detritus of a tropical river as described by H N Mosely in his account of the "Challenger" Expedition compares as though it were an authentic record of what had existed in the London Clay sea fifty million years ago.

 

PALAEOECOLOGY OF THE LONDON CLAY OF THE ISLE OF SHEPPEY

PRESERVATION

Vertebrates, mostly in phosphatic or claystone nodules

Plants mostly in Pyrite

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Vertebrates mostly in nodules, shark teeth little changed, Cephalopods in nodules with unchanged shells, wood, unchanged or pyritised, bivalves, gastropods. largely pyritised

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Molluscs - mostly in pyrite, shell not often preserved (also applies to corals and brachiopods)

Crustacea in soft buff coloured phosphatis nodules as are most other larger vertebrate remains.

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Molluscs - mostly in pyrite, shell not often preserved. Pyrite is syngenetic forming rapidly within shells after death - is known to fossilise soft tissue.

Land

Mammals - Hyracotherium, Coryphodon - Argillotherium (creodont carnivore) Crocodiles, marsh terapins, seeds, fruit, wood twigs, cones.

Air

Birds - A few truly marine forms, some woodland but mostly open well drained habitats.

 

PELAGIC / NEKTONIC Deep sea, evidenced by the sharks Anamotodon sheppeyensis, Megascyliorhinus cooperi and Triakis wardi

Teleost fishes

Nautiloids Cimomia, Deltoidonautilus Sepoids (cuttles) Belosepia, Belopterina -

Pterapods

Sea crocodiles, Sea snake (Palaeophis), turtles
Drifting logs, bored by 'shipworm' ( Teredo) and carrying the gastropod Litiopa and the bivalves ( Modiolus tubicola, Pterelectroma media, pholads, goose barnacles, etc. (similar to the Sargaso sea today)

SEA FLOOR - EPIFAUNAL

Gastropods - browsers, scavengers Buccinids, Tibia, Falsciolarids (Fusinids), cerithids, Ficidae, Xenophoridae

Gastropods - carnivores, cones, cowries, muricids, turrids, volutes, Epitoniidae (feeding on coelenterates)

Scaphapods ( tusk shelles) feeding on forams, plankton

Bivalves, suspension feeders, Pectens, Oysters, Ptereletroma Brachiapods, suspension feeders Ligula, Terebratulina Crustacea, scavengers - crabs - lobsters

Corals - Paracyathus, Graphularia (sea fan)

SEA FLOOR / SEA BED / SEA WATER INTERFACE - trace fossils, (coprolites, worm casts, burrows etc)

SEA BED INFAUNAL

Gastropods - suspension feeders Aporrhais, Turritella gastropods - carnivores - (feeding on bivalves and other gastropods) Euspira, Sinum (Naticidae)

 

Bivalves - most genera

Abra, Arctica, Astarte, Calpitaria, Cuspidaria, Glycymeris, Nucula, Pinna, Thyasira, Verticordia

From a Field guide prepared by J. Cooper & D. Ward November 1977