A2/M25 roadworks reveal Neanderthal Occupation

Fig. 2

As most KAS members have no doubt been aware, major improvements have been recently made to the junction of the M25 with the A2, south of the Dartford crossing. The roadworks, funded by the Highways Agency with the main contractors being Jacobs Babtie and Costain, were accompanied by archaeological investigations, carried out by Oxford Archaeology between 2003 and 2006. What is probably less well known, is that the archaeological programme had a major Palaeolithic/Pleistocene element, carried out under the direction of Francis Wenban-Smith (School of Humanities, University of Southampton), which has produced important evidence of Neanderthal occupation early in the last glaciation, at a period when Britain has until now been thought to be entirely deserted.

More than 75 separate trenches were dug, mostly small (but very deep!) test pits, but also several much larger stepped trenches allowing direct access to deeper-lying deposits of potential interest. A range of evaluation and mitigating work was carried out all around the junction, a full report on which has been prepared and will be available through the Archaeology Data Service. The work described here took place in the northeast quadrant, where a direct link was constructed between the southbound carriageway of the M25 and the eastbound carriageway of the A2 (Fig 1). A few test pits dug for preliminary geo-archaeological evaluation had established that deep Pleistocene sequences were present in this area, including gravel bodies thought to be of fluvial origin. Since one of the primary project aims was to develop understanding of the history of Pleistocene landscape development, and this part of the site was to undergo substantial impact, it was agreed to excavate a continuous stepped trench through these deposits. This trench (TP 8800) may be Britain’s largest ever archaeological test pit, reaching 160m long and 4m deep (Front Cover).

The resulting section revealed that in fact few fluvial sediments were present. Rather, when seen as part of a wider whole, deposits that in isolation appeared to be fluvially lain and well-bedded were revealed as part of a chaotic jumbled mass that dipped and thickened downslope, representing a massive build-up of slopewash sediments, probably formed under cold climatic conditions. These deposits produced a huge pointed handaxe (Front Cover - Insert), obviously derived out of its original context and so of uncertain age.

At the southern end of the trench a thick silt/sand body extended broadly horizontally for more than 50m, overlying an undulating gravel sheet, which in turn stratigraphically overlay the mass of slopewash sediments. Two flint flakes were found in situ in the trench section, at the interface where the base of the silt/sand body overlay the gravel sheet (Fig 2). These were absolutely unstained and unpatinated, and in such mint condition, that they did not appear to have been subject to any depositional disturbance. It was inferred that the surface of the gravel...

At this point we had no idea of the age of this occupation. No biological remains were apparent (confirmed by environmental sampling), so the only feasible dating technique was optically stimulated luminescence (OSL), carried out by Jean-Luc Schwenninger of the Research Laboratory for Archaeology and the History of Art, University of Oxford. Samples were taken: (a) from a sand bed within the underlying gravel sheet; and (b) from a sandy part of the silt/sand body overlying the occupation horizon. The results suggested that the occupation horizon dated to between c. 115,000 and 90,000 BP (years Before Present), corresponding with marine isotope stage (MIS) 5d-5c, early in the last (Devensian) glaciation, and a period when Neanderthals are the only hominin species present in Europe, with abundant evidence of their presence known from northern France.

Britain, in contrast, is currently thought to have been unoccupied throughout the last (Ipswichian) interglacial, corresponding with MIS 5e, and to have only been reoccupied in MIS 3, c. 60,000 BP, represented at sites such as Lynford (Norfolk) and Coygan Cave (Carmarthenshire, Wales) where bout coupé handaxes have been found in deposits of this age. There would have been no reason why Neanderthals could not have survived in Britain during the last interglacial — there is abundant evidence from the continent and from earlier periods of them surviving under analogous conditions — so the presumption is that they couldn’t get here because of the Channel. This new evidence suggests that, rather than waiting around for some reason, Neanderthals entered Britain almost as soon as the Channel sea-level dropped at the start of the last glaciation. In fact Kent is probably the first place they reached, having crossed on what would have become the exposed plain (‘Boulogia’?) between, and to the west of, the Dover strait, perhaps enticed by the visible flint-rich chalk downs of east Kent, which also probably supported huge herds of desirable large herbivores such as mammoth, rhino, horse and deer.

It is uncertain why it has taken so long for evidence of this phase of occupation to be discovered, and why it seems so rare. It may be that we lack, in the UK, deposits of this period that preserve hominin evidence such as the last glacial loess beds of northern France or the caves and rockshelters of Belgium. Or it may be that we have devoted insufficient attention to the cold-climate slopewash deposits that we do have, under the misapprehension that they do not contain evidence of sufficient integrity to have any interpretive potential — perhaps we need to start looking harder, and in different places.

Francis Wenban-Smith
Department of Archaeology,
University of Southampton.