Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing,

David Nash et al have released a new paper on the Sarsen Sources of Stonehenge:

T. Jake R. Ciborowski, David J. Nash, Timothy Darvill, Ben Chan, Mike Parker Pearson, Rebecca Pullen, Colin Richards, Hugo Anderson-Whymark,

Local and exotic sources of sarsen debitage at Stonehenge revealed by geochemical provenancing,

Journal of Archaeological Science: Reports,  Volume 53, 2024, 104406, ISSN 2352-409X,

https://doi.org/10.1016/j.jasrep.2024.104406.

(https://www.sciencedirect.com/science/article/pii/S2352409X24000348)

Abstract: The application of novel geochemical provenancing techniques has changed our understanding of the construction of Stonehenge, by identifying West Woods on the Marlborough Downs as the likely source area for the majority of the extant sarsen megaliths at the monument. In this study, we apply the same techniques to saccharoid sarsen fragments from three excavations within and outwith the main Sarsen Circle to expand our understanding of the provenance of sarsen debitage present at the monument. Through pXRF analysis, we demonstrate that the surface geochemistry of 1,028 excavated sarsen fragments is significantly affected by subsurface weathering following burial in a way that cannot be overcome by simple cleaning. However, we show that this effect is surficial and does not have a volumetrically significant impact, thus permitting the subsequent use of whole-rock analytical methods. Comparison of ICP-AES and ICP-MS trace element data from 54 representative sarsen fragments with equivalent data from Stone 58 at Stonehenge demonstrates that none are debitage produced during the dressing of this megalith or its 49 chemical equivalents at the monument. Further inspection of the ICP-MS data reveals that 22 of these fragments fall into three distinct geochemical ‘families’. None of these families overlap with the geochemical signature of Stone 58 and its chemical equivalents, implying that sarsen imported from at least a further three locations (in addition to West Woods) is present at Stonehenge. Comparison of immobile trace element signatures from the 54 excavated sarsen fragments against equivalent data for 20 sarsen outcrop areas across southern Britain shows that 15 of the fragments can be linked to specific localities. Eleven of these were likely sourced from Monkton Down, Totterdown Wood and West Woods on the Marlborough Downs (25–33 km north of Stonehenge). Three fragments likely came from Bramdean, Hampshire (51 km southeast of Stonehenge), and one from Stoney Wish, East Sussex (123 km to the southeast). Technological analysis and refitting shows that one of the fragments sourced from Monkton Down was part of a 25.7 cm × 17.9 cm flake removed from the outer surface of a large sarsen boulder, most probably during on-site dressing. This adds a second likely source area for the sarsen megaliths at Stonehenge in addition to West Woods. At this stage, we can only speculate on why sarsen from such diverse sources is present at Stonehenge. We do not know whether the fragments analysed by ICP-MS were removed from (i) the outer surface of Stones 26 or 160 (which are chemically distinct to the other extant sarsen megaliths), (ii) one of the c.28 sarsen megaliths and lintels from the c.60 erected during Stage 2 of the construction of Stonehenge that may now be missing from the monument, or (iii) one of the dismantled and destroyed sarsen megaliths associated with Stage 1 of the monument. With the exception of the fragment sourced from Monkton Down, it is also possible that the analysed fragments were (iv) pieces of saccharoid sarsen hammerstones or their pre-forms, or (v) small blocks brought on-site for ceremonial or non-ceremonial purposes.

Keywords: Stonehenge; Sarsen; Silcrete; Geochemical provenancing; pXRF; ICP-AES; ICP-MS

David kindly explained the findings on X (née twitter) 

https://threadreaderapp.com/thread/1750941470075371525.html

First, we analysed 1,028 sarsen fragments from 3 trenches dug at Stonehenge in 2008 using pXRF to see if there were differences within and between the trenches. In short, there weren't, due to subsoil weathering effects. Morale: don't bother using pXRF for this sort of thing.

Second, we analysed 54 sarsen fragments from the 3 trenches using ICP-MS. This is where it gets interesting. Comparison of the geochemistry of fragments against data for 20 sarsen outcrop areas across southern Britain shows that 15 fragments can be linked to specific areas.

Eleven sarsen fragments were likely sourced from Monkton Down, Totterdown Wood and West Woods on the Marlborough Downs (25–33 km N of Stonehenge). Three fragments likely came from Bramdean, Hampshire (51 km SE of Stonehenge), and one from Stoney Wish, East Sussex (123 km SE).

You might be thinking "Wow, Neolithic people dragged sarsen boulders all the way from Hampshire, East Sussex and other sites on the Marlborough Downs to build Stonehenge, not just from West Woods!" Not quite. Calm down, calm down.

We cannot tell if the fragments are from extant megaliths, or from stones from earlier phases of Stonehenge, or stones that have been removed. It is also possible the fragments were from saccharoidal sarsen hammerstones, or stone brought to Stonehenge for some other reason.

There is one exception - a sarsen fragment sourced from Monkton Down that we know (thanks to expert refitting by Ben Chan) was part of a 25.7 × 17.9 cm flake removed from the outer surface of a large sarsen boulder, most probably during on-site dressing.

We're pretty sure this boulder isn't on site today, unless it is stone 26 or 160, which have a different chemistry to the other extant sarsens. However, it adds a second likely source for the Stonehenge megaliths in addition to West Woods. I'll leave it there. Happy reading!