Has Stonehenge drifted off its line?

This post is the companion to the short film Has Stonehenge drifted off its line? Stonehenge was laid out on the solstice axis about 2500 BC. Three slow movements could have shifted that line since: the wobble of the Earth's axis, the easing of its tilt, and the drift of the ground itself. Only one of them has moved the solstice sunrise by a measurable amount. The numbers, methods and caveats follow.

The question

The main axis of Stonehenge runs from the midsummer sunrise in the north-east to the midwinter sunset in the south-west, at 49.95° true (49.81° on the National Grid; Thom et al. 1974). The sarsen structure is taken here as built about 2500 BC. The question is whether anything has since moved the line between the stones and the Sun.

Stonehenge in 2500 BC (red) and today, about 100 m to the north-east. The two axes are parallel. Plan from T. Daw's 3D model.

1. Precession: the stars change, the sunrise does not

The Earth's axis wobbles like a spinning top, tracing a cone about once in 25,800 years. The north pole of the sky moves with it. Thuban, in Draco, "passed within 0.1° of the pole in 2800 BC" (Rawlins & Pickering 2001); today the pole lies near Polaris. Using the long-term precession model of Vondrák, Capitaine & Wallace (2011) and Thuban's J2000 position (proper motion ignored), the closest approach comes out at 0.05° in 2791 BC, consistent with that figure.

Precession changes which stars stand behind the Sun at the solstice, and the calendar date of the solstice. It does not change where the solstice Sun rises. At a solstice the Sun's declination equals the obliquity, plus or minus, and the rising azimuth depends only on declination, latitude, the altitude of the horizon and refraction (Meeus 1998; Ruggles 1999).

The path of the north pole of the sky from 2800 BC to 2026 (gold), on its 25,800-year circle (dotted). Vondrák et al. 2011.

2. The tilt: the sunrise has moved about one degree

The obliquity, the tilt of the Earth's axis to its orbit, has fallen from 23.973° in 2500 BC to 23.436° today (Vondrák et al. 2011, through the ERFA library; Laskar 1986 gives 23.974° for 2500 BC). That is a change of 0.537°. Taking 2700 BC or 2300 BC instead gives 23.992° or 23.954°.

Where the Sun appears on the skyline also depends on how high the skyline is. The horizon was computed from the Environment Agency's 1 m LiDAR terrain model (5 m beyond 2 km), from the centre of the circle (51.1789° N, 1.8262° W) with the eye 1.5 m above the ground, allowing for the curvature of the Earth and terrestrial refraction. Stones and trees are ignored. To the north-east the skyline is a ridge about 2.7 km away, 0.57° high at the 2500 BC sunrise and 0.60° at today's. To the south-west it lies about 4.3 km away, at 0.46–0.49°.

With Bennett's (1982) formula for refraction and a solar semi-diameter of 0.267°:

• Midsummer sunrise, first gleam: 49.33° in 2500 BC, 50.42° today, a shift of 1.09°. With the half disc showing, 49.79° to 50.86°; with the whole disc risen, 50.25° to 51.30°.
• Midwinter sunset, last gleam: 230.02° in 2500 BC, 231.08° today, a shift of 1.06°.

The Sun is 0.53° across, so the sunrise has moved about two widths of the Sun. Moving the date of construction 200 years either way changes these azimuths by less than 0.05°. Refraction near the horizon varies with the weather by a few tenths of a degree; that moves both dates alike and leaves the shift unchanged.

The north-east skyline from the centre of Stonehenge, from Environment Agency LiDAR, with the first gleam of the midsummer Sun in 2500 BC and 2026. Vertical and horizontal scales equal.

3. The ground: Rujm el-Hiri

The third movement is the ground itself. Rujm el-Hiri is a large stone ring in the Golan Heights, about 150 m across, with a central cairn. Aveni & Mizrachi (1998) proposed that its layout held solstice and other sky alignments. Khabarova, Birkenfeld & Eppelbaum (2024) argued from geomagnetic evidence that the whole region has rotated, and that this undermines the observatory interpretation. Their figure (section 3):

"Assuming the average rotation velocity of 10 mm per year and the age of the studied prehistoric site as 4000 years, we will receive an arc rotation of about 40 m. The corresponding direct movement can be estimated as 30 m to its today's position."

The paper gives a distance. It gives no angle through which the site has turned.

The Sea of Galilee and Rujm el-Hiri. Lake outline: Natural Earth.

The rings of Rujm el-Hiri (schematic) and the paper's 30 m shift, drawn to the same scale.

A shift is not a turn

The Sun is so far away that its light arrives in parallel lines. Sliding a monument sideways, by 30 m or 30 km, leaves every bearing within it unchanged: a line that pointed at the solstice sunrise still does. To spoil a solar alignment, the ground has to turn, and by something like the width of the Sun, about 0.5°.

No rotation angle is published for Rujm el-Hiri. As an order of magnitude only: fast block rotations measured from palaeomagnetism run at 1–20° per million years, which over 4,500 years gives 0.005–0.09°. That is well short of a Sun-width. This bound is ours, not the paper's.

Diagram: a monument slid sideways still points at sunrise; turned, it does not. Movement and angles exaggerated.

Stonehenge on the Eurasian plate

Stonehenge sits on the Eurasian plate, which rotates slowly about a pole in North America. Evaluating the plate's rotation at the monument:

• ITRF2014 plate motion model (Altamimi et al. 2017; Eurasia ω = −0.085, −0.531, 0.770 mas a year): 16.5 mm a year north and 16.5 mm a year east, so 23.4 mm a year on a bearing of 045°. Over the 4,525 years since 2500 BC that is 106 m: 75 m north and 75 m east.
• NNR-MORVEL56 (Argus, Gordon & DeMets 2011; pole 48.85° N, 106.50° W, 0.223 ± 0.009° per million years): 21.7 mm a year on 043°, 98 m since 2500 BC.

These speeds are measured against the average motion of all the plates (the no-net-rotation frame), which is a convention. Relative to Africa or North America the figures differ; the rotation of the ground under Stonehenge, which is what matters for an alignment, does not depend on the frame chosen.

The Eurasian plate (shaded) and its boundaries, PB2002 (Bird 2003), with Stonehenge's motion. Inset: the monument's 106 m since 2500 BC, to scale.

Has Stonehenge turned?

The component of the plate's rotation about the local vertical at Stonehenge is 2.5 arcseconds anticlockwise since 2500 BC (ITRF2014; 1.8 arcseconds with NNR-MORVEL56), or 0.0007°. Moving 75 m north also raises the latitude by 0.00067°, which moves the solstice sunrise by 2.5 arcseconds, also anticlockwise. The monument and the sunrise have turned the same way by the same amount, so the alignment between them has changed by well under an arcsecond.

A larger term is polar motion: the slow drift of the spin axis relative to the whole crust. At today's secular rate of about 3.5–4 milliarcseconds a year, much of it from rebound after the last ice age and not necessarily constant over 4,500 years, it amounts to roughly 16–18 arcseconds of pole shift, of order 0.005°.

Taking everything together, the ground under Stonehenge has turned by less than a hundredth of a degree against the sky. The easing of the tilt has moved the solstice sunrise about a hundred times further. Stonehenge has moved about 100 m, but its solstice line has not turned.

Change in the solstice sunrise since 2500 BC: precession 0°, tilt about 1°, drift under 0.01°.

Corrections to the 2025 post

The post of 8 January 2025, "The tectonic movement of Stonehenge", reached the right conclusion: continental drift has not changed Stonehenge's solstice alignment by any measurable amount. Four of its figures need correcting:

• "approximately 25 millimeters per year": about 22–23 mm a year (21.7–23.4 mm, depending on the model). "About 2 cm a year" stands.
• "125 meters northward" in 5,000 years: about 100 m north-east since 2500 BC, of which about 75 m is northward. Over a full 5,000 years the total would be about 115 m.
• "rotating clockwise": the Eurasian plate rotates anticlockwise about its pole in North America; at Stonehenge, about 2.5 arcseconds anticlockwise since 2500 BC.
• "one-thousandth of a degree of latitude": 0.00067°.

Notes on the film

Every number in the film was computed for it from open data, with the scripts in the film's folder: the horizon from Environment Agency LiDAR, the Sun's positions with the ERFA implementation of Vondrák et al. (2011), the plate motion from the published rotation poles, and the path of the celestial pole. Published horizon profiles were used only as a cross-check. The plan of Stonehenge is from T. Daw's 3D model; the rings of Rujm el-Hiri are a schematic; maps use Natural Earth and the PB2002 plate boundaries. The film quotes only the 2024 paper's own figures for Rujm el-Hiri. Music: original.

Sources

• Altamimi, Z., Métivier, L., Rebischung, P., Rouby, H. & Collilieux, X. 2017. ITRF2014 plate motion model. Geophysical Journal International 209, 1906–1912. doi:10.1093/gji/ggx136
• Argus, D. F., Gordon, R. G. & DeMets, C. 2011. Geologically current motion of 56 plates relative to the no-net-rotation reference frame. Geochemistry, Geophysics, Geosystems 12, Q11001. doi:10.1029/2011GC003751
• Aveni, A. & Mizrachi, Y. 1998. The geometry and astronomy of Rujm el-Hiri, a megalithic site in the southern Levant. Journal of Field Archaeology 25, 475–496. doi:10.1179/009346998792005261
• Bennett, G. G. 1982. The calculation of astronomical refraction in marine navigation. Journal of Navigation 35, 255–259. doi:10.1017/S0373463300022037
• Bird, P. 2003. An updated digital model of plate boundaries. Geochemistry, Geophysics, Geosystems 4, 1027. doi:10.1029/2001GC000252
• Daw, T. 2025. The tectonic movement of Stonehenge. sarsen.org, 8 January 2025.
• Environment Agency 2022. LIDAR Composite DTM 1 m. Contains Environment Agency data. © Environment Agency copyright and/or database right 2022. Open Government Licence v3.0.
• Khabarova, O., Birkenfeld, M. & Eppelbaum, L. V. 2024. Discussion points of the remote sensing study and integrated analysis of the archaeological landscape of Rujm el-Hiri. Remote Sensing 16, 4239. doi:10.3390/rs16224239
• Laskar, J. 1986. Secular terms of classical planetary theories using the results of general relativity. Astronomy & Astrophysics 157, 59–70.
• Meeus, J. 1998. Astronomical Algorithms, 2nd edn. Willmann-Bell.
• Rawlins, D. & Pickering, K. 2001. Astronomical orientation of the pyramids. Nature 412, 699. doi:10.1038/35089138
• Ruggles, C. 1999. Astronomy in Prehistoric Britain and Ireland. Yale University Press.
• Thom, A. et al. 1974. Stonehenge. Journal for the History of Astronomy 5, 71–90.
• Vondrák, J., Capitaine, N. & Wallace, P. 2011. New precession expressions, valid for long time intervals. Astronomy & Astrophysics 534, A22. doi:10.1051/0004-6361/201117274

A new henge?

 

Lidar Lens View

Adam Ibbotson and ‪@WC21UKProductionsLtd‬ published a Youtube video today - below - in which they notice an unrecorded henge like shape. Of course I had to find it using the Lidar Lens,  link above. Intriguing. Watch the video for more:

Adam comments: 
More like “stumbled upon” / rediscovered 😅 As mentioned, Mr Phil Barrett emailed me a screenshot of one of them 4 or 5 years ago. He found they were already recorded.

Stonehenge Day at Springhead SP7 - 21st November

Saturday 21st November is Stonehenge day, in aid of the Springhead Trust.

This is an exciting opportunity to meet up with some of the team behind the epic 11-part YouTube series Stonehenge: Access All Areas.The Definitive Series with Julian Richards, archaeologist, filmmaker and writer.

This will not be a series of lectures with a bit of time for questions, but will, like our previous successful Stonehenge days, be a genuine opportunity for discussion, to hear some of the very latest ideas about Stonehenge and its landscape, and to ask questions!

The day will start with tea/coffee at 10.00am and run through until about 4.00pm when we will conclude with afternoon tea.

Tea and coffee will be provided but lunch is self-catering. Please bring whatever you need as Springhead is in a rural location with no nearby shops or takeaways.

Tickets to Stonehenge: Access All Areas cost £50.00 per person plus a booking fee and are available here from Ticketsource.

We will also be offering an additional activity on the Sunday morning: tickets will be made available to those attending on Saturday for an optional Stonehenge landscape walk guided by Julian Richards. This is open only to those who have been part of the Saturday event. Tickets will cost £20 per person and details will be shared with those attending on the Saturday in due course.

All proceeds will go to support the work of the Springhead Trust.


Springhead
Fontmell Magna
Shaftesbury
Dorset SP7 0NU

Phone: 01747 811853
Email: info@springheadtrust.org.uk

The Assize Courts, Devizes, a 3D model

 

https://timdaw37.github.io/assize-courts-3d

Wiltshire Museum is redeveloping the old Assize Courts. To help me visualise the plans I built a 3D model from the planning drawings so you can see the building as it is now and as it's planned. You can walk round it, look inside the courtrooms and entrance hall, and switch between the two views.

I'm an amateur, and this is version 1. It was made without specialist architectural tools, from the published planning drawings, LiDAR and open map data. It won't be perfect, but I don't think it's bad. Corrections are welcome.  The interiors still need refining.

Explore it here: https://timdaw37.github.io/assize-courts-3d

The model is open source and free to reuse. The code is on GitHub at TimDaw37/assize-courts-3d under the MIT licence, so you can copy it, adapt it and share it, as long as you keep the credits. If you spot something wrong, such as a window in the wrong place, a missing detail or a height that looks off, please tell me in the comments or raise an issue on GitHub.  Please keep the data credits (Environment Agency LiDAR, OpenStreetMap, Historic England and OS) when you reuse it.

Avebury and Stonehenge in 3D, rebuilt on the LIDAR

The two landscape fly-throughs, Avebury and Stonehenge, have been rebuilt from the ground up. Both were first made on Ordnance Survey Terrain 50, a 50 m height grid with 10 m colour bands. That is fine for the shape of the downs, but nothing archaeological survives in it: Silbury Hill had to be cut out of the terrain and modelled, and every bank and barrow was drawn on top of a surface that could not show it.

Both models now stand on the Environment Agency's 1 m LIDAR terrain model. The ground is a 5 m (Avebury) or 6 m (Stonehenge) mesh for shape, shaded from the full 1 m data, so the henge ditch, the barrow groups, the lynchets and the hollow-ways are the surveyed surface rather than a drawing of it.

As it is today, and as built

Each model now has two views.

• As it is today shows the LIDAR surface alone, with the barrows as rounded stumps, the Cursus banks a few centimetres high, and the roads, plantations and Larkhill camp alongside them.
• As built cuts the ground away under each monument and lays a fresh-chalk reconstruction on the ground beneath. The phase buttons add each period's earthworks in turn, from the Mesolithic posts to the Middle Bronze Age fields.

The reconstructions are indicative: the plan is the surveyed one; the heights and depths are typical original dimensions, not measurements.

Avebury: what the LIDAR changed

• The henge. The ditch now follows the line the LIDAR traces, 161 to 200 m from the centre, not a 210 m circle. The four causeways sit where the LIDAR ditch shallows, at bearings of about 73°, 165°, 254° and 331°, rather than exactly north, south, east and west. The ditch is still five to six metres below the bank today.
• The stones. The outer circle has 98 stones (it had 44), the inner circles 27 and 29 (they had 12 each), with the Cove and the Obelisk added.
• West Kennet long barrow. The surviving mound is 3.3 m high and 94 m long, and its high, broad end is to the east (bearing 85°). The earlier model had the façade at the west end.
• East Kennett long barrow. It lies NW–SE, broad end to the south-east, 28 m from the OpenStreetMap position.
• Round barrows. Eight of the 25 were matched to mounds that survive in the LIDAR. The rest have been ploughed out and stay at their recorded positions.
• Silbury Hill is the LIDAR mound itself. The as-built view recuts its quarry ditch.

Stonehenge: monuments from Historic England's aerial mapping

The Stonehenge model goes further. Its monuments now come from Historic England's aerial investigation mapping, the bank and ditch outlines plotted from aerial photographs and LIDAR, rather than from OpenStreetMap points. That data puts 843 prehistoric bank and ditch features in the frame, sorted into the phases by monument type and period.

• Early Neolithic: the cursuses, the causewayed enclosures and the long barrows.
• Late Neolithic: Stonehenge, Durrington Walls, Woodhenge and Coneybury.
• Beaker and Early Bronze Age: more than five hundred round barrows and ring ditches, and the Avenue.
• Middle Bronze Age: field systems and lynchets.

For each mapped earthwork, the as-built view lays down a 2 m surface: the LIDAR with the surviving earthwork smoothed away, and the bank and ditch rebuilt on the mapped plan.

• The Greater Cursus. The old model drew it as a straight east–west line at one northing. The mapped cursus is angled, with about 340 m of northing between its ends, and closes on the long barrow Amesbury 42 at the east. Where Historic England's mapping has gaps in the banks, the model leaves them.
• The fields. The earlier model had a generated coaxial grid, labelled as indicative. That has gone. The Middle Bronze Age view now picks out only the field banks and lynchets that are mapped.
• The Mesolithic posts stand at their surveyed positions in the old car park (Cleal et al. 1995). They no longer appear in the Neolithic views; they did not stand for four thousand years.
• Names and phases. Bluestonehenge is now West Amesbury henge, and the Avenue is shown with the Beaker period, when it was dug.

The stones, the timber circles at Woodhenge and Durrington, Larkhill causewayed enclosure and West Amesbury henge are placed by hand from published plans. Larkhill and West Amesbury leave nothing visible in the LIDAR.

Using them

• Moving: drag to turn, scroll to zoom toward the pointer, right-drag to pan; W, A, S and D walk across the ground. Double-click anywhere to move the centre of rotation there.
• Readout: shows the grid reference and height of whatever you are looking at.
• Save still: writes the current view as a PNG at twice screen resolution, with the labels and credits drawn in.
• LIDAR grey: swaps the landscape colour for a plain hillshade.
• Guided tour: still runs through each period with captions.
• Vertical slider: the vertical scale is exaggerated so the chalk reads; at ×1 it is true to life.

They are heavy pages, built for a desktop or a large screen. On a phone, adding ?lite to the address loads a coarser mesh without shadows; very old phones may still not manage the Stonehenge textures.

The Stonehenge model is the phased, as-built companion to the Stonehenge landscape flyover, which stays the place for the ground as it is now, the sky and alignment checks.

Ground: Environment Agency LIDAR Composite DTM 1 m, © Environment Agency copyright and/or database right 2022 (Open Government Licence). Monuments: contains Historic England data © Historic England 2026 (Open Government Licence), aerial investigation mapping; © OpenStreetMap contributors (ODbL). Reconstructions are indicative.

Cheddar to Bath , via Bristol November 1940 Aerial Film

The previously blogged Wiltshire run is the second half of a much longer sortie. NARA holds 254 prints from the two cameras under box GX 10484, and the item records place them on a single loop. The aircraft crossed the Devon coast at Sidmouth (L 1), flew north past Honiton to the Blackdown Hills, then north-east by Taunton, Bridgwater and the Levels to Cheddar, the Mendips and Bristol. North of Filton it turned east and south, and came back by Doynton and Keynsham to Bath and Freshford, where the Wiltshire frames begin at L 109. After Wiltshire it crossed the New Forest and left the coast at Barton-on-Sea (L 148): some 255 km on the long-lens camera alone.

The film above joins the long-lens frames from Cheddar to Freshford, L 56 to L 108. Fair-weather cumulus covers much of the Mendips, Dundry and Bristol (L 62–88); the ground still matches between the clouds, so the frames join, but the clouds sit far above the ground and shift between exposures. Exposure 86 and exposure 91 are not in the NARA set. L 86 is bridged by a small overlap between 85 and 87; L 91 leaves a short break in the film.

Over Bristol the frames come closer together. Over the Mendips successive frames are about 1,000 scanned pixels apart, over the city about 600, and the camera clocks agree: roughly one exposure every 20 seconds from L 56 to L 76, against one every 10 seconds from L 76 to L 85 (minute-hand readings by eye, good to about half a minute). NARA lists L 87–92, north of Filton, as obliques, although at least L 88 appears near-vertical; the label may reflect the aircraft banking into the turn. No record found names a target.

Bath is clear. On L 105 the Royal Crescent and the Circus stand out above Royal Victoria Park, seventeen months before the air raids of April 1942.

Bath on L 105, 29 November 1940: the Royal Crescent (centre) facing Royal Victoria Park, with the Circus above it. Turned to read roughly north-up. Luftwaffe, NARA RG 373, GX 10484.

Bristol through broken cloud, Bedminster to Ashley Down, L 76–84.

Notes on the film

The landscape film runs at about four times real speed and is turned so that the aircraft flies left to right. Each frame is captioned with its exposure number, NARA's nearest place name and its clock reading. The Cheddar to Bath film is a director's cut, without captions, and ends where the Wiltshire film begins. The music is original.

Sources

• National Archives and Records Administration. German Flown Aerial Photographs, 1939–1945. RG 373, series NAID 306065; file units GX 10484 SG. catalog.archives.gov/id/306065
• National Archives and Records Administration. Target Dossiers Pertaining to the British Isles, 1938–1945. RG 242, series NAID 3371016. catalog.archives.gov/id/3371016
• National Collection of Aerial Photography. German Air Force (Luftwaffe), GB 551 NCAP/4. ncap.as.atlas-sys.com
• Luftwaffedata Wiki. Aufkl. Gr. 123 1940. luftwaffedata.co.uk
• Luftwaffedata Wiki. Aufklärungsgruppe Ob.d.L. luftwaffedata.co.uk
• Daw, T. 2026. The Luftwaffe's Wiltshire. sarsen.org; map at wiltshire-luftwaffe.netlify.app

All photographs: Luftwaffe, 29 November 1940; US National Archives, RG 373, GX 10484, listed as Use: Unrestricted. Frame matching, measurements and film: T. Daw. Methods and scripts: github.com/TimDaw37/wessex-films.

Rising Sea levels at Woolacombe and Saunton

This is a side-hustle from my Ramson Cliff erratic post. While I was looking through the 1940 German reconnaissance photos for that, I wondered whether we could show the effect of rising sea levels on the beaches at Woolacombe and Saunton.

The result is a small interactive map: Woolacombe and Saunton at 12:44 BST, 31 August 1940.

Making it a fair comparison

To make it fair, we matched the position in the tide cycle as closely as we could with modern satellite photographs, then overlaid them. Matching the tide height alone isn't enough. On a flat beach, where the water's edge appears also depends on:

• Time after low water. The 1940 photos were taken about 90 minutes after low water.
• Rising or falling. A falling tide leaves wet sand and pools behind it, so the edge seen from the air lags the real water level. A rising tide pushes in over drier sand.
• The size of the tide. 1940 was a mid-sized tide (6.8 m range at Ilfracombe). Big spring tides move faster and push the waves further up the beach.

For example, a Sentinel-2 image from 27 September 2018 caught the sea at almost exactly the 1940 height. But the tide was falling, 100 minutes before low water, on an 8.3 m spring tide. It looks similar, but it isn't the same moment. So I kept only modern images taken on a rising tide, within 20 minutes of the 1940 timing, and with a tide range within 1.5 m of 1940's.

How the photographs were matched

The photographs were matched in the following manner:

• Time. Each German frame shows the camera's clock. It ran on German summer time (CEST), one hour ahead of British Summer Time, so the Woolacombe photos were taken at about 12:44 BST. A tide model for Ilfracombe, checked against Newlyn's real 1940 record, gives the tide at that minute.
• Tilt. The camera wasn't pointing straight down. It was tilted about 12°, from roughly 8 km up. I worked out the camera's position and tilt and laid each photo over the Environment Agency LiDAR ground heights, so that hills and cliffs fall in the right place.
• Pinning. Each photo was then pinned to thousands of features that haven't moved since 1940: roads such as Marine Drive at Woolacombe and the Saunton road, buildings, and hedge and field corners.
• Accuracy. On fixed features the 1940 photos typically sit within 2–3 m of today's imagery. Marine Drive lines up within 3 m. Among the Saunton dunes, where there is little to pin to, it is about 10 m.
• Modern images. These are Sentinel-2 and Landsat scenes from 1985 to 2023, each timed against the same tide model.

What we'd expect to see

Newlyn, the gold-standard tide gauge, shows about 20 cm of sea-level rise since 1940. On Woolacombe's gentle beach, 20 cm moves the waterline only about 8 m. On the flatter sand at Saunton the LiDAR puts it at around 20–30 m.

Conclusion

On these sorts of beaches it's invisible. Sand moving about and the natural spread of the waterline swamp it. On 1940 film, wet sand and shallow water look alike, so the 1940 edge alone can shift by up to 50 m depending on how it's read. Of 106 modern Landsat and Sentinel-2 readings, 27 match the 1940 tide. On those, the water's edge sits a median of −0.08 m from the predicted tide at Woolacombe and +0.16 m at Saunton. Neither shows a trend that stands out from the noise. The rise is real, but you measure it with a tide gauge, not on a sandy beach.

Explore the map. 1940 photos: U.S. National Archives, RG 373. Contains modified Copernicus Sentinel data. LiDAR © Environment Agency (OGL).