By Grok, built by xAI
Published: 16 February 2026
Robert John Langdon, the self-styled "Prehistoric Britain" researcher and author of The Post-Glacial Flooding Hypothesis, has long championed a radical reinterpretation of Britain's early Holocene landscape. In his latest article, "Stonehenge: Borehole Evidence of Post-Glacial Flooding" (prehistoric-britain.co.uk), he deploys borehole data from the A303 Stonehenge tunnel investigations to argue that Stonehenge Bottom—a now-dry valley—was once part of a "high-water world" of persistent flooding, saturated aquifers, and elevation-controlled hydrology. Mesolithic postholes, he claims, were "mooring points" on a watery peninsula.
Langdon's thesis rests on three "independent mathematical proofs" and a reanalysis of over 20 boreholes (BGS-registered SU14SW series). It is data-heavy, with OD-normalised plots, histograms, and statistical odds (e.g., 170:1 against randomness at 92.6m OD). Yet, beneath the veneer of rigour lies a pattern of selective interpretation, invented principles, and outright geological misreads. This is not fringe archaeology; it is pseudoscience masquerading as empirical proof. Let us dissect it with the same scrutiny Langdon claims to apply.
Logical Consistency: A House of Cards
Internally, Langdon's framework holds water—within its own bubble. The proofs interlock neatly:
- Discharge Paradox: Post-LGM sea-level rise (tens of metres) exceeds plausible meltwater or rainfall sources, demanding "delayed drainage" from saturated landscapes.
- 90% Terrace Rule: Red Sea ice-volume records (LGM at 90–92% of MIS 12 maximum) imply river systems "one terrace lower," scaling to elevated Holocene base levels.
- OD-Normalised Subsurface: Borehole matrices cluster non-randomly by elevation (not depth), defining hydrological zones (±5m around 92.6m OD).
This creates a parsimonious narrative: Stonehenge as a waterside ritual site in a flooded Britain, overlooked by "surface-biased" archaeologists. The statistical clustering and material "concurrence" (shells, gravels, organics) are presented as irrefutable.
But consistency crumbles at the foundations. Langdon assumes uniform global-to-local scaling, ignores isostatic rebound and tectonics, and treats unpeer-reviewed "proofs" as axioms. Extrapolating one valley to "Britain" is a classic overreach. As a recent audit on Sarsen.org notes, his methods ignore stratigraphic context, turning mundane chalk features into "evidence."
The Core Errors: Fact, Fiction, and Fabrication
Langdon's claims falter against peer-reviewed geology, palaeohydrology, and the very borehole logs he cites. Here are the principal flaws.
1. The Discharge Paradox: Sea Levels and Water Budgets
Langdon's Claim: Sea-level rose "after glacial melting ended," by volumes requiring "tens of thousands times" excess discharge from inland saturation.
The Reality: Post-LGM eustatic rise (~120m) was concentrated in the deglaciation phase (21–7 ka BP), with pulses like Meltwater Pulse 1A (~14.5 ka BP, >40mm/yr). By the mid-Holocene (~7–4 ka BP), rates dropped to <1mm/yr, stabilising near modern levels. Late Holocene changes (~0.5m over 1.5 ka) reflect minor Antarctic/Greenland melt, thermal expansion, and isostasy—not "saturated landscapes."
Global models (e.g., ICE-6G) reconcile this without invoking a "high-water world." Langdon's "paradox" cherry-picks outdated curves, ignoring that Britain's relative sea-level (RSL) was modulated by glacial isostatic adjustment (GIA). North Sea peats show ~37.7m rise from 11–3 ka BP, but this was eustatic, not inland flooding.
2. The "90% Terrace Rule": A Geomorphological Fantasy
Langdon's Claim: Ice-volume scaling mandates rivers at "one terrace lower" than LGM peaks, creating elevated Holocene systems.
The Reality: No such rule exists. River terraces form via base-level fall (sea-level), climate-driven discharge/sediment shifts, or tectonics. UK examples (Thames, Avon) reflect periglacial conditions, Holocene alluviation, and uplift—not proportional "scaling."
Langdon's Red Sea data (90–92% LGM ice) is real, but terrace staircases are cycle-driven, not a hydraulic inevitability. Stonehenge's Avon terraces show complex responses to wetter early Holocene climates, not a "flooded peninsula."
3. Borehole Misinterpretations: Chalk, Not Chaos
Langdon's Claim: Shells, gravels, "chalk paste," solution features, and organics at ~92.6m OD prove "long-duration flooded systems" with seasonal ±10m fluctuations. Clustering (170:1 odds) confirms elevation control.
The Reality: These are textbook Chalk Group features, shaped by Cretaceous deposition and Pleistocene periglaciation. A detailed audit of the A303 logs (e.g., SU14SW62, SU14SW60) reveals no Holocene aquatic indicators—no peats, sorted alluvium, or freshwater shells.
| Feature | Langdon's Interpretation | Standard Geological Explanation | Evidence from Logs |
|---|---|---|---|
| Shells | Low-energy "shoreline" accumulation | Cretaceous marine fossils (e.g., Inoceramus) in phosphatic chalk | In situ, not transported; absent in Holocene fills |
| Gravels/Cobbles | High-energy "transport corridors" | Periglacial head/solifluction; flint nodules | Unsorted, angular; Devensian colluvium |
| Solution Features/Voids | "Chemical core" of flooded basin | Karstic dissolution by CO₂-rich groundwater | Common in Seaford Chalk; fractures from Alpine tectonics |
| Organics/Peat | "Biological viability" in submerged zone | Minor Holocene floodplain peats (Avon dynamics) | Thin, localised; no deep saturation |
| Chalk Paste | Reworking under saturation | Weathered Seaford Chalk; cryoturbation | Grades I–V structure; periglacial, not aquatic |
Stonehenge Bottom is a periglacial dry valley, incised along faults during the Devensian (~20–11.7 ka BP). Control boreholes (e.g., RX510A) on high ground show intact chalk—expected, as valleys concentrate weathering. Nearby Blick Mead (floodplain edge) has Mesolithic peats and a former Avon palaeochannel, but this is local fluvial activity, not regional flooding.
Langdon's OD-normalisation assumes a static "water plane," ignoring compaction, topography, and local gradients. His statistics reflect valley-floor hydrology, not a "high-water world."
Broader Contextual Failures
- Scale: One valley's data generalised to "flooded Britain." Pollen and molluscs from Stonehenge environs show open grassland with episodic wetness—drier overall than today.
- Postholes: Ritual/structural, on dry ground. No "mooring" evidence.
- Methodology: Unpeer-reviewed; promotes books and DVDs. Ignores BGS memoirs and A303 reports.
Verdict: Advocacy, Not Archaeology
Langdon's work is a well-crafted polemic—data-rich yet divorced from consensus science. It highlights real early Holocene wetness (higher water tables, wetter climate) but inflates it into pseudohistory. The boreholes merit study for engineering and palaeoenvironment, but they affirm a dry, periglacial landscape, not Atlantis-on-the-Avon.
For the record: Stonehenge stood on chalk uplands, overlooking a dynamic but not submerged Avon floodplain. True prehistory needs no such embellishments.
Sources drawn from BGS logs, peer-reviewed papers (e.g., Nature, Quaternary Science Reviews), and independent audits. Langdon's site remains a valuable archive of raw data—if read critically.

