Ramson Cliff erratic: a second thin section still points Cornubian, not glacial

A second thin section, same answer: still more Cornubian than glacial.

Prof Slack has kindly loaned a second thin section cut from the original hand specimen of the Ramson Cliff (Croyde) epidiorite — the ~700 kg block at ~80 m OD on Baggy Point. Discussion with Dr Mik Markham, who knows Cornubian greenstones and the axe-head groups as well as anyone, prompted a fresh transmitted-light description. It confirms the account in Daw, Ixer & Madgett (Quaternary Newsletter 167, 2026) with only small corrections.

The rock is a highly altered ophitic microgabbro with relict clinopyroxene, no olivine and no quartz. Secondary minerals are dominated by brown-green hornblende and colourless-to-green actinolite, two generations, with actinolite the later, and by minor chlorite, epidote and clinozoisite. Biotite and white mica were not confirmed. That assemblage matches the outer aureole of the Dartmoor Granite as described in the BGS Okehampton memoir, and is consistent with Cornubian contact metamorphism more broadly. It does not match non-aureole Devon or Cornish greenstones, which reach actinolite grade only and carry albitised, sericitised feldspar; nor does it match the Welsh Ordovician metadolerites on the Irish Sea route. A Scottish Dalradian source cannot be excluded on the amphibole evidence alone, but remains less likely on transport grounds; further tests on the relict pyroxene chemistry and plagioclase composition would settle it.

What has not changed is the emplacement argument. The block has been used as evidence that Irish Sea ice reached ~80 m OD on this coast. That reading was already thin: first recorded standing upright in pasture in 1969, absent from earlier maps and photographs, angular and unabraded, and the only claimed erratic on the south Bristol Channel shore above ~30 m OD. A Cornubian source does not prove human movement, but it does make a lone high-level glacial drop even less likely. A second slide from the same specimen does not turn an isolated, poorly documented boulder into proof of high-level ice, nor into a stepping-stone for glacial bluestones on Salisbury Plain.

Full description below.

---

Rob Ixer's Analysis

A second thin section from the original hand specimen was generously loaned by Prof Slack and prompted discussions with Dr Mik Markham, an authority on Cornubian greenstone axes and on the petrography of Cornubian altered greenstones.

A petrographical examination of it confirmed the original petrographical description (Daw et al. 2026) albeit with some minor corrections. The un-named green amphibole is identified as actinolite. Trace amounts of white mica/muscovite and mixed muscovite-chlorite were not confirmed (the latter was probably misidentified mixed chlorite–limonite-stained chlorite) but trace amounts of epidote with high interference colours were. The suggestion that the rock could be Cornubian in origin is maintained.

The rock is a highly altered microgabbro, hence locally plagioclase–pyroxene have their characteristic ophitic relationship. It comprises relict primary pyroxenes showing both high and low interference colours, unaltered to highly altered plagioclase feldspar, and skeletal and equant-shaped opaques including probable titanomagnetite. The degree of alteration varies on a small scale and secondary alteration minerals are dominated by brown-green amphibole (‘hornblende’) and green actinolite and minor chlorite, with trace amounts of titanite, epidote and clinozoisite. White mica, if present, is very rare. Amphiboles replace and pseudomorph pyroxene but also occur as discrete and distinctive fine-grained mosaics intergrown with chlorite and enclosing very minor titanite, possible zircon and feldspar (perhaps albite). Texturally there is a strong suggestion of more than one generation of amphibole, with actinolite being the later.

Unzoned polysynthetically twinned plagioclase is variably altered from largely unaltered to highly altered, hence much relict feldspar is present. The main alteration is to fine-grained actinolite crystals, with this alteration initiated along cleavage and twin planes. Very minor amounts of chlorite, epidote with high interference colours and probable clinozoisite with low interference colours accompany actinolite. Plagioclase altering solely to fine-grained clinozoisite is rare; fine-grained white mica could not be positively identified.

Pyroxene displaying both high and low interference colours is the only primary mafic mineral; no olivine or pseudomorphs after olivine are present. Relict pyroxene is enclosed within lower-relief amphibole; both are in optical continuity. Much pyroxene is altered to colourless to grey-brown-green amphibole with a good cleavage and with very fine-grained titante lying along that cleavage; this amphibole is enclosed within green actinolite rims. Amphibole fringes about pyroxene are absent but total replacement is common. Other pyroxenes are altered to green actinolite along cleavage and fracture planes or to mosaics of fine-grained stubby actinolite. Locally pyroxene with low interference colours is altered to amphibole with unusual yellow interference colours.

Although a positive identification of the opaques is not possible in a normal thin section, their habit (equant and skeletal) and texture (abundant opaque ilmenite laths within a less opaque different phase; titanite replacing magnetite) strongly suggest the presence of altered titanomagnetite. Lobate opaques that would suggest ilmenite are absent. Opaques are replaced/pseudomorphed by actinolite and an opaques–actinolite association is widespread.

Pleochroic colourless to green actinolite (brown-grey-green amphibole is absent from this association) forms mosaics comprising euhedral to subhedral blocky crystals. Although some replace/pseudomorph pyroxene and opaques, most infill spaces between plagioclase laths; all mosaics are fine-grained but they vary in grain size between aggregates. Some just contain actinolite, others actinolite in minor chlorite, and a few are chlorite-rich with actinolite laths, often radiating, growing into the chlorite. Trace amounts of titanite, a high-relief accessory mineral within its pleochroic halo (zircon perhaps) and small twinned feldspar with fluid inclusions (possibly albite) are present but rare.

Colourless to very pale green pleochroic chlorite with blue and very rarely brown interference colours is the second most abundant secondary mineral after amphibole in amount, but is uncommon. It forms thin cross-cutting veinlets or occurs as a very minor secondary mineral in plagioclase. Most chlorite occurs as short stubby crystals surrounding stubby actinolite or as the main phase enclosing actinolite laths and enclosing minor titanite and possible albite. Some chlorite laths are intergrown with a phyllosilicate with high interference colours; although superficially it looks like muscovite, it may be limonite-stained chlorite. Biotite and positively identified muscovite were not recognised.

Trace amounts of titanite may replace primary iron–titanium oxides or lie along cleavage planes in pseudomorphing amphibole. Small euhedral rhombic titanite is present within stubby actinolite–chlorite segregations.

Very minor amounts of high-relief epidote form thin laths along twin planes in plagioclase; other high-relief epidote-group minerals with blue interference colours are visually identified as clinozoisite.

Trace amounts of sulphide, now altered to limonite, are associated with actinolite mosaics.

Possible zircon has a pleochroic halo when enclosed in actinolite.

This new petrographical description continues to allow the possibility that the erratic is Cornubian in origin, namely a microgabbro that has suffered contact metamorphism from the underlying granites. It cannot be matched to any of the main IPG Group Cornubian axe groups (Groups I–IV), but nor can many Cornubian axe-heads.

Stonehenge Access All Areas - all the way to 11- the final episode (for now)

Stonehenge 3D Model

Stonehenge 3D Model — deceptively simple

It looks like a toy. Grey boxes, a blueish ring, pink Altar, two bright silver station markers. Orbit with a finger. Tap for coordinates. Switch the sun and moon between today and c. 2500 BC.

Under the Minecraft-box look is a finished layout of the stones — each one placed and sized so lintels sit on uprights — on LiDAR-derived ground that rolls out to the horizon when you turn Terrain on. Tap or hover for OSGB / SU / WGS84 coordinates (same language as the stonehenge-plan page, without draping a plan drawing under the model). Sky controls aren’t just decoration: sunrise and sunset by day of year, moonrise and moonset on a most-northerly ↔ most-southerly dial, with an Epoch switch so the azimuths use the Earth’s obliquity for Modern or for around 2500 BC (flat-horizon geometry, stated plainly).

Phone-friendly controls that tuck away. Labels you can turn on. Coords you can pin. No app store, no login — just open the link.

I’m publishing it as a public baseline others can fork and improve (TimDaw37/stonehenge-block-3d). The hard part was getting the stones to sit true on real ground and the tools to stay quiet. The easy part is what you get to do with it.

I am seriously impressed by this model, there are layers of features built in to an accuracy that no other model has. Have a play.

Brimham Rocks and the Devil's Arrows

European Anthropic Megalithic Transport Interactive Gazetteer

 

European anthropic megalithic transport is a new interactive gazetteer of every case in Neolithic and Chalcolithic Europe where a published petrographic or quarry match demonstrates genuine human transport of architectural stone — as distinct from a stone that arrived by ice, or one simply raised on the rock it was quarried from.

What it shows

Each entry is a matched pair: a monument and an identified source, joined by an arrow whose weight scales with the published distance. The map filters by region and by evidence quality (high vs medium confidence in the underlying source-matching), and carries a schematic overlay of ice-sheet margins — a reminder that in previously glaciated regions, a "close" erratic and a genuinely local outcrop are not the same thing.

A distance histogram sits alongside the map: a large peak under a few kilometres, and a thin tail stretching out to the exceptional cases — Carn Goedog and Craig Rhos-y-felin to Stonehenge, the Orcadian Basin candidate source for the Altar Stone, Matarrubilla's palaeo-estuary haul at Valencina. Tapping a bar isolates that distance band on the map.

Stonehenge's four hauls can be switched off entirely with a "Not Stonehenge" toggle, so the rest of the European record — Brittany's orthogneiss, the Guadalquivir sites, Newgrange's quartz and greywacke, the Devil's Arrows' Millstone Grit — can be read without one monument dominating the picture.

Sourcing

Every line traces to a cited quarry-provenance study — petrographic, geochemical, or direct archaeological identification of an extraction site — not to tradition or inference from stone type alone. The underlying data is downloadable as CSV, and the full gazetteer lists sources and references for each entry. Corrections and additions, particularly for regions still thin on the map, are welcome via the GitHub repo.

Braemore, not Sarclet: at least they're updating

The Telegraph today has Stonehenge's Altar Stone "formed in Braemore, Caithness," with Dr Remy Veness saying it "seems likely it came from within a 50km [30-mile] radius of Braemore," and the body copy declaring that "the sandstone around Braemore is the closest match."

That is a striking upgrade from the peer-reviewed paper Veness co-authored earlier this year.

What the paper said

Clarke, Veness et al. (2026), From Highlands to Henge (J. Quaternary Science):

"the sample most similar to the Altar Stone zircon population is the ORS at Sarclet (p-value = 0.96)"

"The Altar Stone detrital zircon cargo is also indistinguishable from ORS at Braemore, Kirtomy and Portskerra"

"(i) Sarclet & Braemore, combined and henceforth named as Caithness"

"both approaches identify Sarclet as the closest match"

Conclusion: Caithness or Inverness–Black Isle — a region, not a village.

Sarclet was the headliner. Braemore was the supporting cast, unquantified beyond p > 0.05.

What this blog said (with numbers)

5 July 2026 — Independent audit of that Sarclet claim (sarsen.org):

"Independent replication confirms the broader claim (four of five localities are statistically indistinguishable) but does not reproduce Sarclet as uniquely strongest. Braemore matches comparably or better."

Locality	Replication p	Clarke et al. (2026) reported
Sarclet	0.865	p = 0.96 (strongest claimed)
Braemore	0.889	p > 0.05 (not quantified)

"Braemore matches as well as or better than Sarclet across discordance thresholds and resampling scenarios."

3 September 2026 — fragment-by-fragment check (sarsen.org):

"Two of the three [fragments] are a closer match to Braemore than to Sarclet — the same ranking the July audit found on the pool."

"The group-level result is a Caithness neighbourhood (Sarclet, Braemore, Kirtomy, Portskerra), not a single harbour."

Also as Daw (2026), Screening the Orcadian Basin (10.13140/RG.2.2.10365.12008).

What the Telegraph said today

Standfirst: formed in Braemore, Caithness.

Veness: "within a 50km … radius of Braemore."

Body: "The sandstone around Braemore is the closest match for the Altar Stone."

Sarclet does not get a look-in. The paper's own closest-match locality has been quietly demoted in favour of a site the paper treated as one of several.

Meanwhile: Doggerland still fails Ockham

The provenance tweak is the interesting bit of today's coverage. The transport story wrapped around it is not.

The Telegraph retells the glacial-assist narrative: ice picks the stone up in Caithness, dumps it on Doggerland, Mesolithic people then somehow salvage and move it before the North Sea takes the place, and Neolithic people later finish the job to Salisbury Plain. That chain fails Ockham's razor in several large ways — and the paper itself already admits most of them.

The ice does not want to go there. Modelled flow from Caithness is predominantly north-east. A south-east stream to Dogger Bank needs a narrow, special-case pathway (often with an extra nudge into the Moray Firth first). You are not riding the main current; you are picking the one corridor that keeps the glacial story alive.

The clock does not work. Dogger Bank was inundated by post-glacial sea-level rise well before the Altar Stone is likely to have reached Stonehenge. So the model needs not only ice delivery, but a rescue from rising water, an intermediate storage site on dry ground, and a second anthropogenic haul centuries later. Each step is an unforced complication.

You still need people for hundreds of kilometres. Even under the assist model, glacial transport alone "cannot account for the final emplacement on Salisbury Plain." The hard problem — moving a six-tonne shaped block a very long way — remains. The glacier only relocates where the human journey is supposed to start, and adds a drowned landscape and a time gap in between.

The simpler hypothesis is still on the table. Neolithic people moved Scottish stone (and cattle, and other heavy things) by sea and river. One intentional long journey from a Caithness neighbourhood beats: rare ice vector + inundation race + Mesolithic salvage + later Neolithic re-transport. Ockham prefers the journey you already have evidence people could organise.

The paper's abstract is more careful than the press: glacial transport may have been an intermediate stage; substantial anthropogenic transport would still have been necessary. Today's coverage sells the ice. That is a choice.

Who is selling the ice

It may not be an accident of journalism. Dr Remy Veness is co-lead author, a glaciologist (Sheffield Hallam), and the modeller behind the ice-flow trajectories. He is the natural press voice for a glacial story. He is a less natural sole arbiter of which Caithness outcrop the zircons prefer — that is a detrital-geochronology argument, already published with Sarclet as closest match, now orally revised toward Braemore.

Having a glaciologist as the public face of the paper puts a predictable slant on which half of the work gets the standfirst. Provenance (zircon neighbourhood in Caithness) is the result that actually tightened. Glacial assist to Doggerland is the speculative half — interesting to model, weak under Ockham, and still incomplete without people. When the same voice updates the source pin and re-promotes the ice narrative, readers should separate the two. One is a ranking of open grain lists. The other is a preferred transport romance.

Braemore will not be the final word

One more thing, from this side of the desk. Even if today’s press line is catching up with the July zircon ranking, Braemore will not be the final word, in my view. The open audit never made it a quarry: it only showed Braemore matching better than Sarclet inside a neighbourhood. Later screening — thermal maturity against the Altar Stone’s expandable clays, facies, and a multi-proxy desk filter — moved the priority off that Lower ORS pin. By mid-July the same exercise had narrowed to a single field-accessible target; I published that conclusion and withheld the place-name pending a final check (Algorithm Result, 14 Jul 2026). So when Veness now sells “within 50 km of Braemore,” he is updating an intermediate ranking, not the end of the search. Braemore is a useful waypoint. It is not, in my opinion, where this settles.

Links

• Telegraph, 12 Sep 2026
• Clarke et al. (2026) JQS: https://doi.org/10.1002/jqs.70080
• Independent Audit, 5 Jul 2026
• One Sample at a Time, 3 Sep 2026
• Daw (2026) RG: https://doi.org/10.13140/RG.2.2.10365.12008

Britain, 5000–2000 BC: no ice, no catastrophe, a familiar climate

An interactive, fully referenced viewer of published palaeoclimate proxies for Britain across the Stonehenge-building millennia is now online: 

Climate of Britain, 5000–2000 BC.

It draws on twelve independent proxy records: peat water tables, cave speleothems, lake chironomids, ice cores, ocean sediment, a pollen-based reconstruction and tree rings, each carrying its own citation, archive link and stated uncertainty. Three findings fall out of it directly.

Stonehenge - 2013 - Tim Daw

The Avon would not reliably have frozen thick enough to drag stones over

One proposed route for moving sarsens to Stonehenge has them dragged across the River Avon on a surface of thick winter ice. The pollen-based reconstruction gives a direct check on this: mean January temperature for Wessex across all four millennial slices in the window comes out at 2.7–4.2 °C — above freezing, and close to the modern Boscombe Down January average of 4.0–4.6 °C. A monthly mean sitting a few degrees above 0 °C does not rule out individual cold spells or short-lived ice, but it argues against the sustained, reliable deep freeze that dragging multi-tonne stones across a river would need. On this proxy evidence, an ice-covered Avon load-bearing enough for sarsen transport looks like the exception rather than something that could be counted on.

Glacial transport of the stones themselves is a separate and much earlier question, belonging to the last glaciation many thousands of years before this window opens; it isn't addressed by this dataset one way or the other.

No coherent climate catastrophe, and no population-ending event

The most-cited candidate for a climate-driven population collapse in this period is the "4.2 ka event," dated to around 2200 BC. Roland et al. (2014) tested this directly against the British and Irish peat record and found no regionally coherent, prolonged shift to wetter or colder conditions at that date — the four records that do show any change disagree with each other in timing, duration and structure. The one genuine regional exception is a centennial cold interval in eastern England dated to roughly 4320–4210 cal BP, identified from lake isotopes at Diss Mere and independently from tree-ring isotopes in the Fenland — real, but local to eastern England, about a century long, and not an island-wide catastrophe. Nothing in the compiled proxies supports a climate event severe or widespread enough to end a population.

The climate was not very different from today's

The pollen-based reconstruction (Mauri et al. 2015) gives four millennial temperature and rainfall estimates for the Wessex grid cell containing Stonehenge, referenced against the Boscombe Down climate normals — the nearest long Met Office record. The central estimates:

Slice	Annual mean °C	July °C	January °C	Annual rainfall mm
5050 BC	9.6	17.4	2.7	~730
4050 BC	10.1	16.7	4.2	~815
3050 BC	9.6	16.7	3.8	~870
2050 BC	9.6	16.5	4.0	~840
Boscombe Down, 1971–2000	9.85	16.75	4.0	736
Boscombe Down, 1991–2020	10.42	17.1	4.6	783

Every one of the four central annual-mean estimates sits within half a degree of the modern 1971–2000 average, and all are a little cooler than the current (1991–2020) average — Wessex has warmed slightly since, rather than the Neolithic and Bronze Age being markedly colder than today. Including the full published uncertainty (±1σ, propagated across the window), the plausible annual-mean band is roughly 8.6–11.1 °C: comfortably straddling both modern baselines. Winters may have run a little cooler in the earliest slice (5050 BC: ~2.7 °C January vs 4.0–4.6 °C today), but by the Beaker period the estimate is close to indistinguishable from now. Rainfall is centrally similar to modestly wetter than today, with an uncertainty band wide enough to include "about the same." None of this supports either an unusually harsh or an unusually benign climate: mid-Holocene Wessex was, within the resolution these proxies allow, a maritime temperate climate much like the one standing at Stonehenge today.

Full series, citations, archive links and uncertainty notes for every proxy are in the interactive viewer.