Report of Field Meeting to Castle Hill, Newhaven, & Telscombe Cliffs, Sussex

Sunday 20th May 1999

Director: Jackie Skipper


 

Dr. J. Skipper, Room 110, Natural History Museum, Cromwell Road, London SW7 5BD.

INTRODUCTION

Over twenty members and guests gathered on a cold, cloudy, windy and slightly drizzly day in the car park below this famous section, which is beneath the old hilltop fortifications on the west side of the estuary at Newhaven (TQ 448 000). The last TRG trip had been in 1976 (Bone, 1976), and the section has previously been described by Mantell (1822, 1833), Prestwich, (1854), Whitaker, (1871), and Dupuis & Gruas-Cavagnetto (1985).

THE CASTLE HILL SECTION

The Director gathered the members at the base of the cliff to point out the various features of the Palaeocene Lambeth Group that could be seen overlying the somewhat brownish cliffs of Cenomanian Chalk. Unfossiliferous Upnor Formation, with a coarse pebbly basal bed, is seen to overlie the Chalk, but this can be seen to have been cut down into, the subsequent channels being infilled by similar looking, but coarser, less well-sorted, trough cross-bedded sands. Either faulting or solution of the underlying Chalk appears to have controlled the deposition of both these channels and the overlying Woolwich Formation lignitic and shelly facies, which are both thickest in the region of a large gully, by which the field party ascended the cliffs.

The cliff-top Woolwich Formation lignites and shell beds were very dry and overgrown, but members persisted in digging out several small sections in the sediments in an attempt to obtain samples and clarify the succession, which has suffered badly due to repeated land slippage.

Sections of about a metre were dug in the basal lignites, then again about three metres above this. This second section, dug several hundred metres to the west of the gully, and perilously close to the sheer cliff edge, exposed the highest lignites and earliest shell bed occurrences. A blue-grey ball clay was excavated from beneath one of the lignite beds, which the Director considered to represent a reduced, waterlogged soil horizon. This horizon was temporarily replaced in one excavation by a small amount of grey silt containing abundant plant fragments, but despite much lateral excavation, this was not found anywhere else. Similarities between the section at Newhaven and that at Cap d'Ailly, near Dieppe in France, were noted.

More excavations were made at approximately 3-4 metres above this, in Shelly Clays which had reddened horizons very similar to those seen at Gilbert's Pit at Charlton, SE London, and at other sections in the Woolwich Formation in Kent.

Other members concentrated on the top of the section, near the Coastguard's Tower where in situ Blackheath Pebble Beds (Harwich Formation, Thames Group) could be seen, and below which a cemented coquina of Ostrea bellovacina shells occurs. Extensive slippage and vegetation growth, augmented by dumping of builders’ waste, has made the upper part of the section below this almost impossible to interpret at present and, perhaps regrettably, another major landslip will be required before the details of the upper part of the section are completely revealed.

TELSCOMBE CLIFFS

In the afternoon, on a falling tide, a visit was made to Telscombe Cliffs (TQ 395013), where David Bone directed most of the party down a seven-metre-high groyne, (via some insecure-looking iron rungs set into the side) to the beach, which consisted of a wave-cut Chalk platform overlain with pebbles. On previous visits, the Bone family had found cemented blocks on the beach containing shells that had been identified (S. Tracey pers. comm.) as being Woolwich Formation in age. Similar blocks were found by the party, and were discovered to consist of orange-coloured, carbonate- and iron-cemented sand inter-bedded with clayey layers.

Despite initial discussion as to the possibility of these being transported Mesozoic material, the persistent hammering efforts of some of the members was rewarded with a fauna consisting of oysters, corbiculids, Mytilus sp., and several indeterminate gastropods, suggesting that the material was indeed derived from Cenozoic sediments. J. Skipper noted the similarity of the sediment to that of the rare Upper Shelly “Clay” material collected from Clapham Common Brickyard (West Sussex) and also to that found in the uppermost part of the same facies at Croydon, SE London. Other blocks found on the beach, which were not identifiable either as concrete or chalk-derived material, consisted of two large pieces of silcrete and two pieces of dark brown iron-cemented sand with abundant roots.

Other members returned from an exploration of the Chalk platform with a representative selection of fossils, and the party dispersed, taking home a wide variety of materials for further study.

REFERENCES

BONE, D.A. 1976. The Tertiary Deposits at Newhaven, Sussex. Tertiary Research, 1(2): 47-49.

DUPUIS, C. & GRUAS-CAVAGNETTO, C. 1985. The Woolwich Beds and the London Clay of Newhaven (East Sussex): new palynological and stratigraphical data. Translated from the original in the Bulletin d’Information des Geologues du Bassin de Paris, 22 (2): 19-33 by Ansell, M, edited by Jarzembowski, E. A. The London Naturalist, 75: 27-39.

MANTELL, G. 1822. The Fossils of the South Downs, or Illustrations of the Geology of Sussex. Mantell, London. p.257.

MANTELL, G. 1833. The Geology of the south-east of England. Mantell, London. pp. 24, 53-56.

PRESTWICH, J. 1854. On the nature of the strata between the London Clay and the Chalk in the London and Hampshire Tertiary Systems. Part 2. The Woolwich and Reading Series. Quarterly Journal of the Geological Society of London. 10: 75-170.

WHITAKER, W. 1871. On the cliff sections of the Tertiary Beds West of Dieppe and Normandy and at Newhaven, Sussex. Quarterly Journal of the Geological Society of London. 27: 263.


Modified 22nd December 1999