Sizewell C: the story so far

Who did what, where, when – and why?

Oxford Cotswold Archaeology’s ongoing excavations on the site of the planned Sizewell C power station in Suffolk have uncovered a vast array of features and finds spanning 6,000 years of history. Project Manager Richard Mortimer guides us through some of the most significant discoveries to-date.

Four years into our excavations on the Suffolk Coast, Oxford Cotswold Archaeology (OCA) has so far examined some 140ha (350 acres) across 75 separate areas. This fieldwork builds on seven years of initial evaluations, and while several substantial investigations remain to be tackled, all of the sites explored so far are now undergoing post-excavation assessment, a phase that is due to be completed inthe next three years. The scale of this long-running project is mirrored by the extent and diversity of the archaeology that has been uncovered to-date, some of which I will outline here.

Our principal excavations lie within a 12 square kilometre block located between the villages of Sizewell, Leiston, and Theberton, as well as the Minsmere Nature Reserve, while further links extend along the routes of the Sizewell Link Road and the Two Village Bypass, and at new Park and Ride sites at Darsham and Wickham Market. While these latter schemes are necessarily linear or discrete, what sets this project apart is that the main programme stretches across a single, uninterrupted expanse of land. For the first time in this region, we can examine archaeology on a landscape scale, understanding how this area was used from the Early Neolithic to the present day. Across a broad sweep of varied geology and topography, patterns of occupation start to emerge – and, with them, the possibility of addressing archaeology’s fundamental questions: questions that are echoed by the subtitle of this article.

The landscape’s geological diversity is as important as its geographical scope. Were the project flipped to the west, it would sit entirely on the Lowestoft Formation Diamicton – the boulder clay of Suffolk’s central ‘uplands’ – and its archaeology would look very different. In particular, it would be lacking in early prehistory: the people of the Middle Iron Age were the first to leave a major archaeological footprint up there. As it happens, though, we occupy the eastern fringes of that clay, encompassing the underlying glacial sands and gravels and, further east still, the Pliocene Crag sands; peats and alluvial soils also infill the deeper valleys towards the sea. Within the outline of our investigations, the land falls c.20m to sea level, and the resulting variation in subsoil and contour creates distinct archaeological niches. Put simply, only certain people do certain things in certain places, due mainly to underlying soil conditions and the availability of water.

What follows is only a snapshot of our ongoing work, but it offers glimpses of the excitement and archaeological potential already visible, and of some of the directions in which our research may lead. This story will change over time. It may change tomorrow. That is the nature of archaeology.

EARLIEST ACTIVITY

At Sizewell, the Neolithic arrives with a bang and departs with something of a whimper. Fragments of Early Carinated Bowl occur in a handful of places, sometimes alongside stylistically later Plain Bowl forms, but these traces are slight, almost will-o’-the-wisps. The true ‘Big Bang’ at Sizewell comes around 3800 BC, in an explosion of pit-digging accompanied by tree- and scrub-clearance. The people who were modifying the landscape in this way had arrived with the full ‘Neolithic package’ of pottery, grain, and domestic livestock – and they came from the sea.

We have excavated four main areas of Neolithic activity so far, strung along the 14m–18m (46ft–59ft) contour on the sandy gravels, just below the diamicton, as well as a dozen smaller sites. Adding to this picture, a longbarrow, one of only a handful known in the county, lies on the edge of this zone of occupation. The main sites are represented by groups and loose scatters of numerous, small, ‘standard’ Neolithic pits, which are here interpreted as latrine pits. Some of these are accompanied by much larger storage pits, which are among the project’s most visually striking discoveries. Measuring up to 2.4m (8ft) in diameter and 2m (6.5ft) deep, these vertically sided, flat-bottomed features had been deliberately and rapidly backfilled with clean sand, midden waste, and burnt material at the end of their use-life. Our most plausible interpretation of their purpose is overwinter grain storage, located next to fields that were being prepared, ploughed, planted, weeded, and harvested by the same people who dug the latrine pits – contentious, perhaps, but compelling.

The largest, and perhaps most permanent, of these early sites (B) produced a dozen storage pits and at least 100 ‘latrine’ pits, along with a wealth of material evidence: some 3,000 pottery sherds, more than 10,000 struck flints, five polished axes, and a substantial saddle quern with pounder. This concentration of activity lies lower on the slope beside what would have been a seasonal stream, at a location where a well could have been sunk into the water table. Water is scarce in this landscape, limiting more permanent settlement to a few specific locations, such as this one. We can already see differences between the finds from this location and other large, broadly contemporary sites 0.7km (0.4 miles) and 1.3km (0.8 miles) to the east, which bodes well for future research into whether activities at these places varied as well, hinting at the specific reasons that people were active at each location. Different toolkits, numbers of people, and lengths of stay would be required to plant a field, weed it, harvest it, and process the crop, or to coppice a woodland and harvest it for firewood or timber for fences and other construction. Exactly the same questions can be posed to the project’s Beaker period and Iron Age archaeology, too.

Further storage pits were found within the valleys along the Link Road route to the north. Today, these areas are seasonally waterlogged – one such pit has been under water all winter – which might raise eyebrows: why put sunken storage pits on land prone to flooding? The answer lies in long-term hydrological change: 6,000 years ago, these now-wet coastal valleys were part of the high, dry uplands, then located kilometres from the coast.

The peak of Early Neolithic activity at Sizewell was intense but brief, spanning perhaps 200-300 years from 3800 BC-3600/3500 BC. We can trace this occupation through a shift from Plain Bowl into Decorated Bowl pottery, but after this the Neolithic evidence collapses dramatically and the archaeological signature remains faint for some 1,400 years, with just a handful of Middle and Late Neolithic features and findspots recorded. While this does not necessarily imply that people were not still here, it does indicate that, if they were, they were living their lives in very different ways. It is tempting to link this absence of obvious presence to the thin, sandy soils becoming exhausted after an intense 200 years of farming, perhaps allied to a shift in climate. We might imagine a decreased reliance on arable farming, too, in favour of more ‘light-footprint’ pastoral activity. Arable farming creates pits, and pits produce artefacts; pastoral farming does not.

This is an extract of an article that appeared in CA 434. Read on in the magazine, or click here to read it online at The Past, where you can read all of the Current Archaeology articles in full as well as the content of our other magazines, Current World Archaeology, Ancient Egypt, and Military History Matters.