Origins of the sarsen megaliths at Stonehenge

Abstract

The sources of the stone used to construct Stonehenge around 2500 BCE have been debated for over four centuries. The smaller "bluestones" near the center of the monument have been traced to Wales, but the origins of the sarsen (silcrete) megaliths that form the primary architecture of Stonehenge remain unknown. Here, we use geochemical data to show that 50 of the 52 sarsens at the monument share a consistent chemistry and, by inference, originated from a common source area. We then compare the geochemical signature of a core extracted from Stone 58 at Stonehenge with equivalent data for sarsens from across southern Britain. From this, we identify West Woods, Wiltshire, 25 km north of Stonehenge, as the most probable source area for the majority of sarsens at the monument.

Fig. 1. Stonehenge in context.

(A) Distribution of silcrete boulders across southern Britain, including sarsens and conglomeratic variants known as puddingstone [data from (16, 22, 28, 46, 47)]. (B) Sampling sites and topography in the Stonehenge-Avebury area [areas in pale gray at 100 to 175 m above sea level (asl), and those in dark gray at 175 to 270 m asl], along with proposed transportation routes for the sarsen stones. (C) Plan of Stonehenge showing the area of the monument enclosed by earthworks plus numbered peripheral sarsen stones. (D) Detail of the main Stonehenge monument showing the remaining bluestones and numbered sarsen stones.

Fig. 2. Results of the statistical analysis of PXRF data from all 52 sarsen stones at Stonehenge.

(A) Results of linear discriminant analysis and (B) Bayesian principal component analysis. LD1, linear discriminant 1; PC1, principal component 1. Only selected sarsens discussed in the text are highlighted in each graphic. Covariance of the first six principal components from the BPCA is shown in fig. S1, with the respective element loadings in table S1 (see figs. S2 and S3 for BPCA results for other stones, and figs. S4 and S5 for BPCA results according to the main structural components at the monument). Ellipsoids indicate the 95% normal confidence ellipses.

Fig. 3. Zr-normalized immobile trace element ratio data for 20 sarsen localities across southern Britain and the Phillips’ Core from Stone 58 at Stonehenge.

Data ranges for each of the sarsen localities are indicated by the pink shaded region on each plot. The upper (lower) boundary for each area is defined by the maximum (minimum) Zr-normalized ratio calculated for each element plus (minus) 3 SD of instrumental uncertainty. The solid black line is the median value for each Zr-normalized ratio from the three analyses of the Phillips’ Core. The maximum (minimum) error bars represent plus (minus) 3 SD of instrumental uncertainty.