The Demise of the Glacial Transport Theory for Stonehenge’s Megaliths

 

The Demise of the Glacial Transport Theory for Stonehenge’s Megaliths

Author: Tim Daw

July 2025

Correspondence: tim.daw@gmail.com

Keywords: Stonehenge, bluestones, sarsens, glacial transport, human transport, Neolithic, Craig Rhos-y-Felin, West Woods

Licence: CC BY 4.0

DOI: 10.13140/RG.2.2.17981.37604

 

Abstract

The glacial transport theory for Stonehenge’s bluestones and sarsens, which posits that glaciers conveyed these megaliths to Salisbury Plain, has been a longstanding and contentious hypothesis. Dr. Brian John has been its principal advocate for bluestones, with Hancock et al. (2025) tentatively extending the idea to sarsens. This paper synthesizes recent research by Bevins et al. (2025) and Nash and Ciborowski (2025), among others, to critically evaluate the theory’s validity. Petrographic and geochemical analyses demonstrate that the Newall boulder—a key piece of evidence for glacial transport—is a human-transported rhyolite fragment from Craig Rhos-y-Felin, not a glacial erratic. Likewise, robust geochemical sourcing of the sarsens to West Woods, coupled with the absence of glacial deposits on Salisbury Plain, refutes glacial movement. Archaeological evidence, including Neolithic quarrying sites and parallels in long-distance megalith transport, further substantiates human agency. The glacial transport theory is thus rendered untenable, leaving its remaining proponents the choice to seek improbable new evidence or to contribute to the refinement of human transport models, in alignment with the current scientific consensus.

Introduction

“In science, it often happens that scientists say, ‘You know, that’s a really good argument; my position is mistaken,’ and then they actually change their minds and you never hear that old view from them again. They really do it. It doesn’t happen as often as it should, because scientists are human and change is sometimes painful.” -  Carl Sagan

At the outset of Dr. John’s academic career, the theory of continental drift was resisted by a minority of fixist adherents—a position he likely regarded as reactionary and unscientific (Oreskes, 1999). Today, Dr. John occupies a similar position as the principal proponent of the glacial transport theory for Stonehenge’s bluestones, arguing that glaciers conveyed these stones from West Wales to Salisbury Plain. A comparable hypothesis has been tentatively proposed for the sarsen stones (Hancock et al., 2025). However, recent studies—most notably Bevins et al. (2025) on the Newall boulder and Nash and Ciborowski (2025) on sarsen provenance—have systematically dismantled these claims. This paper synthesizes these findings and broader evidence to demonstrate that the glacial transport theory for Stonehenge’s megaliths is no longer viable in mainstream scholarship, with human agency now firmly established as the mechanism of transport.

Refutation of Glacial Transport for Bluestones

Bevins et al. (2025) conducted a comprehensive re-examination of the Newall boulder, a rhyolite fragment excavated at Stonehenge in 1924 and long cited by Dr. John (2024a) as key evidence for glacial transport. Through petrographic analysis, SEM-EDS, and portable XRF, the boulder was conclusively identified as originating from Craig Rhos-y-Felin in north Pembrokeshire, likely as debitage from the buried stump of Stone 32d. Its foliated texture, presence of stilpnomelane crystals, and geochemical profile—particularly Zr/Th ratios—correspond to Craig Rhos-y-Felin rhyolite, not to other regional sources. Claims of glacial features, such as bullet-shaped morphology or surface scratches, are dismissed as products of natural weathering, with no diagnostic glacial striations present.

Extensive surveys have failed to identify glacial deposits or erratics on Salisbury Plain. Furthermore, the restricted lithological diversity of the bluestone assemblage (12–15 rock types, as opposed to the 46 claimed by John) supports the hypothesis of deliberate human selection from specific Welsh sites. This is corroborated by evidence of Neolithic quarrying at Craig Rhos-y-Felin and Carn Goedog, with radiocarbon dates placing activity between 3400–2900 BCE (Bevins et al., 2025; Parker Pearson et al., 2022a).

While localized ice movement near Mynydd Preseli may have transported some bluestones short distances, the absence of spotted dolerite erratics beyond 18 km renders this geologically insignificant compared to the evidence for Neolithic human transport. The Altar Stone’s origin in the Orcadian Basin (~750 km away), which glaciers could not have transported due to flow directions (Clarke et al., 2024), further undermines the glacial hypothesis. Collectively, these findings leave Dr. John’s position without empirical support, as his primary evidence—the Newall boulder—is conclusively non-glacial.

Refutation of Glacial Transport for Sarsens

Hancock et al. (2024) posited that Stonehenge’s sarsen stones, particularly Stone 58, may have been glacially transported, citing the potential for ice coverage of the Marlborough Downs during the Last Glacial Maximum (LGM). Nash and Ciborowski (2025) refute this, noting that the BRITICE-CHRONO Project (Clark et al., 2022) places the southern limit of the ice sheet far north of Salisbury Plain and the Marlborough Downs. No glacial deposits or erratics have been found in the region.

Geochemical analysis, including portable XRF and Bayesian principal component analysis, confirms that 50 of 52 sarsens share a common chemistry, pointing to West Woods (~24 km away) as the source, not Clatford Bottom or Piggledene as previously proposed (Nash et al., 2020; Nash and Ciborowski, 2025). Methodological flaws in Hancock et al.’s analysis, such as misinterpretation of Zr normalization, further weaken the glacial transport argument. The established human transport of sarsens—some weighing up to 40 tonnes—parallels the evidence for bluestones and underscores Neolithic capabilities for long-distance megalithic haulage.

The Consensus: Human Agency

The preponderance of evidence supports human transport for both bluestones and sarsens. Archaeological investigations at Craig Rhos-y-Felin and Carn Goedog have uncovered stone tools, wedges, trackways, and radiocarbon dates that align with Stonehenge’s construction (~3000 BCE), confirming Neolithic quarrying activity (Parker Pearson et al., 2019, 2022a). The sourcing of the Altar Stone to northeast Scotland and the sarsens to West Woods demonstrates long-distance transport, consistent with other Neolithic sites such as Newgrange and West Kennet, where stones were moved distances ranging from 5 to 80 km (Cooney, 1999; Piggott, 1962).

The absence of glacial features on Salisbury Plain, combined with the precise sourcing and restricted lithologies of the bluestones, renders glacial transport implausible. The theory’s reliance on speculative claims—such as boulder morphology or hypothetical ice coverage—has been systematically debunked by recent research.

Dr John’s Path Forward

As the sole remaining advocate of the glacial transport theory, Dr. John faces a pivotal choice: persist with a refuted hypothesis or join the ranks of scholars who have embraced new evidence and revised their positions. He may continue searching for erratics or glacial deposits closer to Salisbury Plain, though extensive surveys suggest this is unlikely to yield results. Alternatively, he could contribute his expertise to refining models of Neolithic human transport or exploring cultural connections, as evidenced by sites like Waun Mawn and Crosswell (Parker Pearson et al., 2021). His legacy may thus be shaped either by intransigence or by a willingness to prioritize evidence over prior allegiance.

Conclusion

The glacial transport theory for Stonehenge’s bluestones and sarsens is no longer tenable. It is not pining for the fjords; it has passed on. Recent studies by Bevins et al. (2025) and Nash and Ciborowski (2025) demonstrate, through geochemical, petrographic, and archaeological evidence, that these stones were not glacially transported. The absence of glacial deposits, restricted lithological diversity, and confirmed quarrying sites leave no empirical foundation for the theory. While proponents of glacial transport have stimulated valuable debate and research, the overwhelming weight of evidence supports Neolithic human agency, situating Stonehenge within broader patterns of prehistoric monument construction.

 

References

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(Richard E. Bevins, Nick J.G. Pearce, Rob A. Ixer, James Scourse, Tim Daw, Mike Parker Pearson, Mike Pitts, David Field, Duncan Pirrie, Ian Saunders, Matthew Power)

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