The World Recreated: Redating Silbury Hill in Its Monumental Landscape
Bayliss, Alex, McAvoy, Fachta, Whittle, Alasdair, Antiquity
There came a time in many past societies when prodigious amounts of labour were directed into great tasks of construction, and few parts of the world are without mounds, pyramids, ziggurats or other substantial earthworks of some kind. Some of these are historically late, such as the mounds of the Mississippian culture, which was at its peak in the period AD 1200-1400. Others go back much earlier, such as the temple platforms of Mesopotamia from the fifth to the fourth millennia BC, followed by the ziggurats of the third millennium, or the first pyramids in Egypt, the earliest of which is the Step Pyramid of Djoser at Saqqara (after 2686 BC, the start of the Third Dynasty) (summarised in Whittle 1997a: 143-4; with references). No one sequence is quite the same, and these massive undertakings were often preceded by smaller enterprises. This sense of change and the scale which developed monuments can reach have prompted many questions. Who thought up these investments? What imperatives drove them? Whose social and political interests did they serve? Did they recurrently appear at significant points in sequences?
The Late Neolithic in southern Britain, broadly speaking in the third millennium BC, is one example of a society which engaged in enterprises of this kind, though not quite on the scale of some of the most extravagant examples worldwide. Impressive constructions in timber, earth, chalk and stone were numerous, but mostly grouped into local complexes, the best known spread across central-southern England (or Wessex) (Renfrew 1973; Wainwright 1989). The earthwork enclosures ('henges') of Avebury and Durrington Walls, containing substantial internal settings of stone and timber, and Stonehenge itself, are prime examples. Clearly these were collective undertakings, in that vast amounts of labour were needed, but how was this mobilised and who, if anyone, directed it? Compared with earlier constructions in the fourth millennium such as long barrows, causewayed enclosures and cursus monuments, what does the change of scale signify?
Many answers have been given to these sorts of questions, which we will return to below. Much is at stake, in terms of the kind of society and the pace and trajectory of change which we envisage at this time. Perhaps all answers so far--and perhaps all the questions too--have been offered within a rather loose or imprecise chronological framework. Material culture studies and individual site sequences offer some sense of order, but radiocarbon dating in this period has usually relied on small numbers of samples, often poorly selected, the results of which have normally been examined informally (cf. Bayliss et al 2007a). Only the chronology of Stonehenge itself has been explicitly modelled (Cleal et al. 1995:511-35; Bayliss et al. 1997; Bronk Ramsey & Bayliss 2000), and as we shall see below, other readings are possible. This lack of chronological precision means that, whatever interpretive camp we may belong to, monuments tend to be lumped together (for an honourable exception, see Garwood 1991). What potentially may have been varied sequences structured by dramatic events, gaps, resumptions, accelerations and decelerations, have not so far been seen, both because we have not been willing to engage with chronology and because the now available methodology which can serve to redress the situation has not yet been consistently applied.
Silbury Hill is a case in point. Despite a long history of investigation and a general ascription to the Late Neolithic, the monumental mound has never been reliably dated. Recent disturbance to the mound, however, has allowed the collection of new samples, and other samples have been obtained from the archive. Thirty radiocarbon measurements are now available, which we interpret within a Bayesian statistical framework. From this, we present two chronological models. These agree in suggesting a date in the third quarter of the third millennium cal BC for the construction of the primary turf mound. …