Megafossil plants from Suffolk: a review of the Pre-Pleistocene records

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MEGAFOSSIL PLANTS FROM SUFFOLK: A REVIEW OF THE PRE-PLEISTOCENE RECORDS H U G H LANCE PEARSON*

The current literature on the palaeoflora of Suffolk is concerned mostly with sub-fossil remains of extant species from Pleistocene strata. Although superficial deposits of that age predominate in the county, older sedimentary rocks also outcrop here (see Table 1). Some of these pre-Pleistocene horizons have yielded megascopic fossils of extinct species of plants. This article summarises the existing accounts describing the Suffolk megafossil flora, and the intention is to present new records for this flora subsequently. The bias towards the Pleistocene Period and the microflora (e.g. pollen, microscopic algae and spores) rather than the megafossil plants in the current literature is due to the predominance of superficial deposits of that age in the county and the greater abundance of microfossils. Although pollen and spores of land plants probably occur in the Palaeogene (Lower Cainozoic Era) of Suffolk, a study of the fossil microflora has only been carried out for the Neogene (Upper Cainozoic Era) at Orford (Andrew & West, 1977). A clay-containing deposit of the Coralline Crag near Raydon Hall Farm, Orford, yielded pollen assigned to conifers and angiosperms, including several genera now restricted to thermophilous ('warmth-loving') floras in North America and eastern Asia. Megafossil plants of pre-Pleistocene age in Suffolk have mostly been obtained from the London Clay of the Eocene Epoch. The London Clay was deposited in a sea covering the southern North Sea basin and extending West to a shoreline running approximately from the Wash to the Isle of Portland (Davis & Elliott, 1958). Thus, fossils of land plants now found in the London Clay of Suffolk originally grew no nearer to the county than Cambridgeshire, or perhaps west Norfolk. Exposures of London Clay in England occur near to their northern limit in Suffolk, an inlier largely obscured by drift near Reedham, Norfolk, being the northernmost recorded (Chatwin, 1961). The number of London Clay exposures in the county is limited due to considerable erosion during mid-Cainozoic times (Carr, 1967) and by its burial beneath the Crags and other Pleistocene deposits. Davis and Elliott (1951), and George and Vincent (1976 a & b) list the main coastal and fluvial exposures of London Clay in Suffolk. The most abundant megafossil plants from the London Clay are pieces of pyritised wood (Daniels, 1971), but these have not been examined as much as similar wood from the London Clay of Kent (Wilkinson, 1984). Permineralised wood is also found in Suffolk in calcified form, obtained either directly from the London Clay (Brett, 1956,1960) or apparently reworked from that horizon and redeposited in the Red Crag (Brett, 1972). Lower Eocene seeds and fruits have been recorded from the London Clay 'Basement Bed' in * The author will be a member of Emmanuel College, Emmanuel Street, Cambridge, CB2 3AP, for one year from September 1987.

Trans. Suffolk Nat. Soc. 23


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Megafossil plants from Suffolk: a review of the Pre-Pleistocene records by Suffolk Naturalists' Society - Issuu