New Borehole Analysis Sharply Constrains the Fremington Clay: True Glacial Lake Limited to Low Elevations (~15–28 m OD), with No Lacustrine Deposit South of the Hele Ridge

Borehole Map from https://api.bgs.ac.uk/sobi-scans/v1/borehole/scans/items/703466

A detailed OD-referenced re-examination of the 1972 C.H. Brannam Ltd borehole campaign (BGS records SS53SW62–79) fundamentally refines our understanding of the Fremington Clay Series in North Devon. This 18-hole dataset, drilled for commercial pottery clay prospecting, provides the first systematic elevation control on the deposit. The results demonstrate that the genuine glaciolacustrine "potters clay" — the stone-free, homogeneous lacustrine unit formed in a proglacial lake — is far more restricted in both lateral extent and elevation than shown on BGS Sheet 293. Much of the mapped "Boulder Clay" is actually periglacial head and solifluction deposits. There is no Fremington lacustrine clay confirmed south of the Hele–Bickington ridge, and no lacustrine clay above ~28–29 m OD.

George Maw (1864) originally described a clear two-unit sequence: a lower stone-free potters clay resting on glaciofluvial gravel, overlain by an independent stony gravel/head produced during later erosion and periglacial reworking. Subsequent work by Stephens (1966) and the BGS (Edmonds et al. 1985) collapsed this distinction through a traceable sequence of conflations — Taylor (1956) had already grouped coastal and inland erratics together, inflating the apparent glacial signature; Stephens then treated the entire surface-to-bedrock sequence as a single boulder clay; and Edmonds mapped the valley floor accordingly, drawing an admittedly arbitrary boundary between boulder clay and pebbly drift. Crucially, Edmonds himself noted in the 1985 memoir that gravel was found only in holes that penetrated smooth clay — the diagnostic key to the whole problem — but never followed this observation to its mapping consequences. The 1972 Brannam logs allow us to restore Maw's distinction with quantitative precision.

Of the 18 boreholes, only 8 reached the diagnostic basal glaciofluvial gravel, confirming the full lacustrine stratigraphy (potters clay on gravel on bedrock). Their gravel-top elevations cluster tightly between 15.3 m and 28.0 m OD, with the basin floor around 20–23 m OD and margins rising to ~27–33 m OD. This matches independent data from the A39 Lake cutting (Cattell 2003: clay base 19.9–26 m OD), Maw's Roundswell well (~26.8 m OD clean clay top), and a 1982 A39 bypass borehole (703458) that positively identifies Fremington Clay at ~20.8 m OD — making 9 confirmed lacustrine holes across the full 31-borehole dataset. The ice-dammed lake surface therefore stood no higher than approximately 27–29 m OD.

Three boreholes (9, 10, 11) at surface elevations 41–43 m OD encountered "clay" tops at 38–40 m OD — 12–20 m above the confirmed lacustrine basin. These are unequivocally periglacial head. The remaining non-gravel holes show poor-quality "dirty" clay consistent with head masking thinner lacustrine deposits or basin-margin facies. The pattern is reinforced by a further sample of 13 archival boreholes: 12 are dominated by head throughout, with no trace of stone-free lacustrine clay. None of these additional holes, nor the 1972 set, records Fremington lacustrine clay south of the Hele–Bickington ridge. Notably, C.H. Brannam Ltd — guided by T.R. Wood's prior seismic survey and by generations of direct working knowledge — drilled entirely on the low ground around the existing pits and showed no commercial interest in the ground south of the ridge. A pottery firm whose livelihood depended on finding workable clay would not have overlooked accessible reserves: their silence on the southern ground is itself evidence (Sutton's Law in reverse) that the mapped Fremington Clay extent there reflects head and reworked material rather than genuine lacustrine deposit.

Implications for Irish Sea Ice Incursion and Erratics

This OD-constrained geometry severely limits models of onshore Irish Sea ice advance (likely Anglian/MIS 12). The Fremington potters clay records only a modest proglacial lake ponded in the Taw–Torridge estuary, not a widespread till sheet from grounded ice overriding the Devon landscape to 80–90 m OD. Ice must have been pinned near the Bristol Channel coast. The restriction of lacustrine clay to ~15–28 m OD directly challenges interpretations that rely on high-level glacial material and extensive ice incursion inland.

For producing a rigorous geological map of the glacial clays — loosely mapped and extensively mixed with head deposits — these boreholes supply critical control points. Future work will include a corrected map separating confirmed lacustrine clay from periglacial head, cross-sections (e.g., Lake–Roundswell transects showing the 11° northward basin-margin dip), and targeted investigation south of the Hele–Bickington ridge.

Relevance to Bluestone Transport

A thick, grounded Irish Sea ice sheet capable of glacial rafting or long-distance transport of erratics across Devon is incompatible with this restricted, low-elevation lacustrine basin. The data strengthen the case for predominantly fluvial/periglacial origins for most superficial "glacial" features and constrain maximum ice-surface elevations in the Bristol Channel. This directly informs the viability (or otherwise) of glacial hypotheses for Stonehenge bluestones.

The full April 2026 report (CC-BY-4.0), with tables, maps, and the unified borehole register (31 holes total), is available: 
Constraining the Fremington Glaciolacustrine Clays: and its implications for the Irish Sea Ice extent

and a related paper: A Case for Predominantly Fluvial and Periglacial Origins of the Fremington Clays, Devon

Stonehenge – Access All Areas. Coming soon

A major new 11-part documentary series from archaeologist Julian Richards

One whiteboard. Hundreds of questions. Decades of digging. Still no neat answers.

How did they move 30-tonne sarsen stones, and bluestones all the way from Wales? What was the route? Why choose those exact stones — and why from so far away? How did they shape, transport, and erect them with nothing but stone, wood, and muscle?

Why align the whole monument so precisely to the midwinter sunset and midsummer sunrise? What does the sun mean to the people who built it? Was this a place of the living, the dead, or something far more profound — a changing society marking time, ancestry, and the cosmos?

Was it a temple? A calendar? An ancestral monument? A healing centre? Or something we still haven’t imagined? Why are some stones missing? Why were others deliberately broken or buried? And why, after 5,000 years, does Stonehenge refuse to surrender its deepest secrets?

Julian Richards has spent over 35 years exploring Stonehenge and its landscape. In this no-holds-barred series he goes Access All Areas — tearing apart old theories that no longer work, testing the latest ideas, following the bluestone and sarsen trails, examining the evidence from digs, scans, and the stones themselves, and confronting everything that still doesn’t add up.

You’ll see the real process of archaeology: the “maybe it was Merlin” guesses, the failed hypotheses, the new data from modern science, the solar alignments, the landscape context, the ancestral connections — and the honest admission that we still don’t know it all.

No fluff. No tidy Hollywood ending. Just rigorous, passionate, on-the-ground investigation into Britain’s greatest prehistoric enigma.

Eleven episodes. From Sunday 3 May 2026.

First episode drops on YouTube: → Subscribe now at youtube.com/@julianrichards1483

If you think you know Stonehenge… think again. This is the series that goes deeper than ever before.

The Boring Hydrology of Stonehenge and Avebury

 

Why Water Tells Us Almost Nothing About the Monuments

In recent years, one researcher has spun elaborate tales of a post-glacial “high-water world” where Stonehenge sat on a watery peninsula, the River Avon was a tidal superhighway, and massive aquifers turned Salisbury Plain into a navigable inland sea until the megalithic age collapsed around 3000 BCE.

The reality is far more mundane.

Ground investigations for the A303 Stonehenge tunnel scheme produced dozens of boreholes that revealed the true nature of the underlying chalk. As detailed in the 2017 paper Stonehenge — a unique Late Cretaceous phosphatic Chalk geology (Mortimore et al., Proceedings of the Geologists’ Association), these cores exposed complex fault-controlled phosphatic chalk deposits and periglacial features formed millions of years ago — but nothing resembling the prolonged post-glacial flooding claimed by some researchers. Instead, they confirm a classic, well-drained chalk downland landscape.

The hydrology of Stonehenge and Avebury is classic chalk downland — well-drained, spring-fed, and locally variable, but fundamentally unremarkable. It explains the placement of a few features (like the Avenue’s route or proximity to the Avon) but offers virtually zero insight into the purpose, design, or cultural significance of the great monuments themselves.

Stonehenge: Dry Uplands Beside a Normal River

Stonehenge stands on a chalk spur at ~100–105 m OD, overlooking the Avon valley. Stonehenge Bottom (the dry valley to the south) is a periglacial feature incised during the Devensian cold stage. Borehole data from the A303 investigations show typical Chalk Group characteristics: solution features, periglacial head deposits, occasional Holocene alluvium in the valley floor, and localised organics — exactly what you’d expect in a well-drained upland with episodic floodplain activity.

• Water table: Modern and Holocene water tables fluctuate but do not indicate persistent deep flooding around the monument. Control boreholes on higher ground show intact chalk. Springs exist (e.g., at Blick Mead, ~2.5 km away), but these are normal chalk springs with stable ~11°C temperatures — attractive for Mesolithic campers, not evidence of a submerged landscape.
• River Avon: A typical chalk river with seasonal flow. The Avenue connects Stonehenge to the river, likely for processional or symbolic reasons (domain of the living vs. domain of the dead, per the Stonehenge Riverside Project). There is no evidence it was a “tidal superhighway” or that stones were routinely floated in vast post-glacial rivers. Bluestones and sarsens were moved overland or by river in manageable stages.
• Ditch and bank: Excavations show the henge ditch filled rapidly with chalk rubble from the weathering sides and bank, with only thin organic-rich “dark layers” that represent soil development or gradual accumulation on a damp base — not evidence of prolonged standing water or a deliberate moat. Chalk is highly permeable, so any water would drain quickly. The ditch was a symbolic boundary, not a water-holding feature fed by aquifers..

Claims of “long-duration flooded systems” at ~92.6 m OD rely on reinterpreting standard karstic, periglacial, and minor alluvial features as proof of exotic hydrology. Standard Quaternary science finds no such need.

Avebury: Even Drier and More Ordinary

Avebury sits in the upper Kennet valley on chalk with thin soils. The River Kennet is a small, intermittent chalk stream (winterbourne). Research shows:

• Low erosion and minimal alluviation in the Neolithic/Bronze Age.
• Springs and wells were important but unreliable in summer — people dug wells into the chalk aquifer.
• The henge ditch could hold seasonal water but was not part of a vast flooded network.

Silbury Hill is a massive, carefully engineered Neolithic mound beside the Kennet. Its surrounding ditch does fill with water seasonally in winter due to the naturally high water table in the valley floor — a phenomenon still seen today after heavy rain, creating a temporary “moat” effect. However, this is ordinary chalk hydrology, not evidence of a permanent flooded harbour or dramatic post-glacial inland sea. Silbury Hill is not a “lighthouse” for boats in a high-water world — its form, construction, and location are consistent with monumental/ritual functions on dry or seasonally damp ground.

Wansdyke, meanwhile, is a much later post-Roman linear earthwork, not Neolithic or prehistoric. It runs up and down the porous chalk ridges of the Marlborough Downs. On such highly permeable geology, it would be as likely to function as a canal as a Martian fault line — any water would simply drain away through the chalk aquifer, and its undulating profile makes no hydrological sense for navigation. Its alignment and profile are consistent with boundary or defensive purposes in a normal, well-drained chalk landscape, not a prehistoric waterway in a “high-water world.”

Silbury Hill and other features interact with local water (e.g., springs near the ditch), but again, this is normal chalk hydrology — not evidence of dramatically elevated post-glacial rivers.

What Hydrology Actually Explains (and What It Doesn’t)

It explains:

• Why people camped at springs like Blick Mead in the Mesolithic.
• Route choices (e.g., the Avenue following a natural corridor to the Avon).
• Practical considerations for construction (access to water for workers, but nothing extraordinary).

It explains almost nothing about:

• Why the monuments were built in these specific locations (solstitial alignment, landscape theatre, ancestral significance, social aggregation).
• The purpose of the stones, circles, or burials.
• The cultural or astronomical motivations.
• The transport and erection of megaliths (human organisation and effort, not super-rivers).

The builders chose well-drained, prominent chalk locations with good visibility and symbolic power. They were not fleeing floods or mooring boats at ritual harbours. The early Holocene was wetter than today with higher water tables in lowlands, but Salisbury Plain and the Marlborough Downs remained open, stable grassland ideal for large-scale monument building — not a saturated swamp.

Conclusion: Boring Is Good

Real hydrology at Stonehenge and Avebury is boring in the best scientific sense: predictable, consistent with regional geology, and fully compatible with mainstream archaeology. It requires no radical reinterpretation of sea-level curves, invented “90% terrace rules,” or global aquifer collapse to explain the monuments.

The monuments’ enduring mystery lies in the human story — ritual, cosmology, ancestry, and communal effort — not in dramatic (but evidence-free) flooded landscapes. Over-hyping the water distracts from what actually matters.

The chalk downs were dry enough, the rivers ordinary enough, and the springs local enough. That’s the truth the boreholes reveal — and it’s far more interesting than the alternative.

The Wreck of the Bluestone Raft - Not historically accurate

Stonehenge - Access All Areas: The Definitive Stonehenge Videos

It's nearly here — the definitive documentary on this most famous pile of rocks in a field: "Stonehenge - Access All Areas".

Episode 1 lands on May 3rd on Julian Richards' YouTube channel.

Three years in the making, what started as a modest plan for three one-hour films has ballooned (in the best possible way) into an 11-episode epic. A collective of proper HengeGeeks — Julian Richards, Luke Winter of Historic Concepts, yours truly here at Sarsen.org, and Simon Banton at Stonehenge Monument — have thrown everything we know into one coherent, no-stone-unturned narrative.

Interviews, road trips, experiments, fieldwork, arguments over bluestone provenance, late-night geology debates… and yes, actual fun. Filmed and edited with the patience of a saint by Steve Shearn, this is the deep dive the stones deserve.

So please head over to Julian's YouTube channel, hit like, subscribe, and share the hell out of it. You can also follow him on Instagram for the behind-the-scenes extras:

https://www.instagram.com/julian_richards_official/

This one’s been a long time coming. Don’t miss it.

Ice Age Tiger Stripes That Inspired Stonehenge?

 

This Google Earth image (dated 27 September 2018, coordinates approx. 52°29'19.20"N 0°39'19.20"E) captures Grime’s Graves in Norfolk from above. The Neolithic flint mine pits appear as circular depressions in the foreground field, while the large open area behind shows clear parallel bands of alternating vegetation — the classic Breckland periglacial stripes (also called tiger stripes). These stripes run across a gentle slope, visible as lighter and darker bands in the grass/heath.

Key Facts About the Stripes at Grime’s Graves

• Formed during the Devensian Stage (last Ice Age, ending ~11,700 years ago) through freeze-thaw cycles, frost cracking, solifluction, and cryoturbation on Upper Chalk bedrock.
• On gentle slopes (1–6°), polygons on flat ground transition into parallel stripes spaced ~7–8 m apart.
• Wind-blown coversand (acidic) infills frost-crack gullies, supporting heather; intervening chalky soil supports grass — creating strong pH and vegetation contrast.
• Confirmed by 2016–17 GPR, boreholes, and soil pits at the adjacent GRIM military training site: tripartite deposits (pellet chalk, gravelly diamicton, chalk rubble) with coversand in gullies.
• Still highly visible today in aerial views and lightly grazed areas; English Heritage notes these “vegetation stripes” as a Breckland speciality, best seen looking north-west from the site (some areas in a danger zone).

Identical Features at Stonehenge

• Excavations along the Stonehenge Avenue revealed parallel periglacial fissures/grooves in the chalk bedrock, formed by the same Devensian processes.
• These align roughly with the midsummer sunrise/midwinter sunset axis.
• Stonehenge Riverside Project researchers (e.g., Mike Parker Pearson, Mike Allen) suggest the natural stripes may have been noticeable to Neolithic people and influenced site selection.

Why the Grime’s Graves Photo Helps Reconstruct the Neolithic View at Stonehenge

• Shared origin: Both sites overlie Upper Chalk subjected to identical periglacial conditions; the stripes are relict patterned ground.
• Better modern preservation at Grime’s Graves: Thick Devensian coversand creates sharp acidic/alkaline contrast that drives vivid heather-grass bands. Salisbury Plain lacks this widespread coversand layer.
• Neolithic conditions at Stonehenge (~3000 BC):
  • Soils thinner: Holocene chalk dissolution and minor truncation estimated at ~0.3 m over ~4,000–5,000 years; Neolithic topsoil was shallower, bringing fissures closer to the surface.
  • Fresher micro-relief: Less time for bioturbation, grazing, and colluviation to smooth contrasts.
  • Differential vegetation likely: In dry summers, silt-filled grooves would support taller/darker grass versus shorter turf on chalk ridges — producing visible parallel lines similar to those in the Google Earth image.
• Homogenisation over time at Stonehenge: Patchy prehistoric cultivation, loess redistribution, and 5,000+ years of pastoral management dulled the surface expression. Today the Avenue stripes are subtle and mainly visible in excavations.
• Breckland as analogue: The photo shows the same Ice Age patterning still expressing strongly in vegetation. Remove modern heather, thin the turf, and sharpen the relief — and you approximate what Neolithic observers would have seen on Salisbury Plain: natural “lines in the grass” leading toward the solstice.

In short, the two photos of Grime’s Graves provide one of the clearest modern snapshots of active-looking periglacial stripes. They strongly suggest that 5,000 years ago the equivalent features at Stonehenge would have been much more obvious on the open chalk downland.

References

• Boreham, S. & Rolfe, C.J. (2016–17). “Imaging periglacial stripes using ground penetrating radar at the ‘GRIM’ training site, Grime’s Graves, Breckland, Norfolk.” Bulletin of the Geological Society of Norfolk 66: 31–43.
• English Heritage guidance on Grime’s Graves (Ice Age stripes description).
• Allen, M.J. et al. (2016). “Stonehenge’s Avenue and Bluestonehenge.” Antiquity.
• Geoarchaeological reports on Holocene soil development and truncation on Salisbury Plain chalk downlands.

Clayton (1994) Glaciation Study - a hidden report

 

Clayton, K. (1994). Glaciation of the British Isles: An approach seeking to determine the role of glaciation in landform development over the last million years. Nirex Science Report NSS/R337. (Nirex Limited, UK). School of Environmental Sciences, University of East Anglia.

Download: https://www.whatdotheyknow.com/request/nirex_report/response/3285600/attach/2/Clayton%201994%20Glaciation%20of%20the%20british%20isles.PDF.pdf

Keith Clayton’s 1994 Nirex Science Report NSS/R337 is an intriguing and somewhat eccentric contribution to the Quaternary literature on the British Isles.

Written by the distinguished geomorphologist Keith Clayton, the report carries the ambitious title Glaciation of the British Isles: An approach seeking to determine the role of glaciation in landform development over the last million years. It was produced not for academic journals or the geological survey, but as an internal Nirex Safety Studies Report (NSS/R337). Nirex (later part of the Radioactive Waste Management programme) commissioned it to inform long-term performance assessments for a potential geological disposal facility for radioactive waste. The core concern was how repeated glaciations over the next million years might reshape the landscape, erode cover materials, alter groundwater regimes, and affect the isolation of buried wastes.

Despite its relevance, NSS/R337 remains an unpublished grey-literature document that is not archived in any public geological library, BGS repository, or academic database. It exists primarily as an internal Nirex/RWM report; copies are scarce. This “unarchived” status is unusual for a substantive review by a senior academic on such a central British Quaternary topic. Most comparable syntheses appear in mainstream journals or BGS memoirs, whereas this one was tailored to the specific (and sensitive) needs of radioactive waste disposal planning. Its limited circulation makes it a classic example of high-quality Quaternary research hidden in the “grey” literature of the nuclear industry — simultaneously influential in niche modelling circles and practically inaccessible to the wider research community.

In short, Clayton (1994) NSS/R337 is a hidden gem: a thoughtful, million-year-scale analysis of glaciation’s role in British landscape development that is highly pertinent to refining the extent and elevation of Fremington Clay deposits, yet oddly elusive because it was written for a purpose far removed from conventional Quaternary mapping or bluestone transport debates.

The Fremington Clays - extent and source.

Two papers uploaded today :

Constraining the Fremington Glaciolacustrine Clays: and its implications for the Irish Sea Ice extent.
and
A Case for Predominantly Fluvial and Periglacial Origins of the Fremington Clays, Devon

Finally I think I have sorted out a lot of misinformation about the Fremington Clays and the implications they have for how far and high the Irish Sea Ice overrode the Devon coast.

The clays are a small area of pure potters clay in the Taw estuary near Barnstaple. Some say they show a 100 m high glacier stormed ashore there. The evidence shows that there was just an ice/debris dam at the shoreline which was about 30 m high.

Why it is important for Stonehenge: the Glacial Transport theory needs a mighty wall of ice to reach Salisbury Plain.

Have a read – they are based on solid geological data not wishful thinking.