The Luftwaffe's Wiltshire

German reconnaissance aircraft photographed Wiltshire repeatedly between August and December 1940, and once more in August 1942. The prints and the Luftwaffe's target dossiers were captured in 1945 and are now in the US National Archives, scanned and free to use. This post explains what survives and how to read it. An interactive map plots every Wiltshire frame and dossier, with a link to each scan.

CLICK HERE to open the map: Luftwaffe Wiltshire

Avebury - an example photo: click it to expand

Avebury henge (top centre) and Silbury Hill (left, beside the A4), 4 September 1940. GX 10004 SG, R, exposure 95, scale about 1:26,000. The titling strip reads GB 1060 R 4.9.40. NARA RG 373, NAID 220881704.

Where the photographs come from

The US National Archives (NARA) holds about 1.2 million Luftwaffe aerial photographs in a series titled German Flown Aerial Photographs, 1939–1945, part of Record Group 373. They are known as GX prints, from the GX numbers that identify each box. The captured material was duplicated and shared between Britain and the United States, and the British holdings are now in the National Collection of Aerial Photography (NCAP) in Edinburgh.

Allied teams found caches of German photographs, maps and target dossiers across Europe in 1945. The material was flown to the Allied Central Interpretation Unit at RAF Medmenham in June 1945 and sorted there until 1949. It later passed to RAF Brampton and, after declassification in the early 1990s, to Keele University. In 2008 it was transferred to what is now Historic Environment Scotland, as part of NCAP. NARA and NCAP have since worked together to scan the prints, and the scans appear in NARA's online catalogue.

A GX citation names the box, the camera and the exposure: GX 10004 SG, R, Exposure 95. NARA describes SG, SK and SD as camera position identifiers. The L, R and S letters within a sortie are not explained in NARA's guidance. In the Wiltshire prints, L and R frames at the same scale run in parallel lines, and S frames are at a smaller scale.

Wiltshire: 129 frames from ten sorties

A search of the NARA catalogue for Wiltshire in the German Flown Aerial Photographs series returns 129 frames. Every one is digitised and listed as unrestricted for use. NARA gives each frame a centre point and the nearest named place in its gazetteer, and the map plots those centres.

Date	Box	Frames	Scale	Coverage (NARA place names)
17 Aug 1940	GX 10096	1	1:57,000	Buttermere
18 Aug 1940	GX 10134	10	1:15,200; 1:38,000	Grimstead, Whiteparish, Landford, Redlynch; Devil's Ditch, Bulford
18 Aug 1940	GX 10135	38	1:23,500; 1:76,000; obliques	Mere and the Knoyles, the Wylye valley, Winterbourne Stoke, Normanton and Lake, Salisbury, Downton
4 Sep 1940	GX 10004	15	1:26,000; one oblique	Purton and Leigh south through Clyffe Pypard, Avebury and the Vale of Pewsey to Bulford and Downton
29 Oct 1940	GX 10238	8	1:15,000	Winterslow, West Dean, Whiteparish, Landford
29 Nov 1940	GX 10484	44	1:20,500; 1:52,000	Winsley and Bradford-on-Avon east along the scarp to West Lavington, across the Plain to Amesbury, then to Clarendon and Redlynch
5 Dec 1940	GX 12048	1	1:8,500	Bradford-on-Avon
11 Dec 1940	GX 11961	7	1:10,000	Box, Kingsdown, Monkton Farleigh, Colerne, Biddestone, Malmesbury
15 Dec 1940	GX 11935	1	1:15,000	Yatesbury Field, Cherhill
28 Aug 1942	GX 12060	4	obliques	Whiteparish, Landford, Redlynch

Two sorties crossed the county on 18 August 1940, the day of the large raids on RAF airfields later called the Hardest Day. GX 10135 alone produced 38 Wiltshire frames, running from Mere across the Wylye valley and the Stonehenge landscape to Salisbury.

The place name in each catalogue entry is the nearest gazetteer entry to the frame centre, not a description of the subject. Exposure 95 of GX 10004 is catalogued at West Kennett Long Barrow. The print shows Avebury henge, with the village inside its bank, and Silbury Hill beside the Bath road. A later hand has written on the back, in English, Avebury Stone Circle – Silbury Hill.

Reverse of the same print. NARA RG 373, NAID 220881704.

The target dossiers

A second NARA series, Target Dossiers Pertaining to the British Isles, 1938–1945 (Record Group 242, records seized from Germany), holds the Luftwaffe's target files. Thirty-six digitised dossiers cover twenty-nine places in Wiltshire, dated 1939 to 1942. A dossier is a set of sheets, usually three:

• an annotated vertical photograph with the target outlined in red, a scale bar, the coordinates and height, and the date of the information (Stand);
• an extract from a 1:50,000 map with the target outlined;
• a printed target card, the Zielstammkarte, filled in by typewriter.

The Alton Barnes dossier (GB 10 391) is typical. The photograph sheet, marked N.f.D. (nur für den Dienstgebrauch, for official use only), outlines an airfield of 1,000 × 850 m. It notes probable administration and accommodation buildings and is dated October 1940. The map sheet is dated November 1940 and carries the stamp of Luftflotte 3 (Lfl. Kdo. 3).

Target sheet GB 10 391 b c, Alton Barnes, Flugplatz, Stand X.40. NARA RG 242, NAID 240794047.

Click to embiggen

The target card records, among other entries:

• Location: 12 km SW of Marlborough; 1° 51′ W, 51° 21′ 30″ N; 136 m above sea level.
• Target: Flugplatz (airfield), compared with the army camps at Marlborough, Chisledon, Yatesbury and Devizes by their own target numbers.
• Significance: Als E-Hafen geeignet, suitable as an Einsatzhafen or operational airfield.
• Description: Woodborough station 3 km S; landing ground about 850 × 1000 m; a few smaller buildings, probably quarters, in the south-east corner.
• Recognition points: the Kennet and Avon Canal along the southern edge; the railway fork of the Newbury–Bath and Newbury–Warminster lines 5.5 km SW.
• Neighbouring airfields: eleven, each with its target number, distance and bearing, from Boscombe Down (GB 10 22, 23 km SSO) to Marlborough (GB 10 887, 9 km NO); O is Ost, east. A red typed addition adds Clyffe Pypard, 14 km NNW, as an Einsatzhafen.
• Information as of: November 1940.

Zielstammkarte (L) for Alton Barnes, Bearbeitungsstand November 1940. NARA RG 242, NAID 240794047.

What the Luftwaffe listed

Each target number begins with a country code and a category. The Wiltshire dossiers fall into four categories, and the type names below are the ones printed on the sheets:

Code	Category	Wiltshire dossiers
GB 10	Airfields (Flugplatz)	Alton Barnes, Boscombe Down, Clyffe Pypard, Colerne, Durrington, High Post, Larkhill, Lyneham, Marlborough, Netheravon, Old Sarum, South Marston, Tilshead, Upavon, West Overton, Wroughton, Yatesbury, Zeals
GB 14	Army camps (Truppenlager, troop camp; Barackenlager, hutted camp; Zeltlager, tent camp)	Bulford, Chisledon, Corsham, Devizes, Durrington, Heytesbury, Marlborough, Melksham, North Tidworth, Porton, Tilshead, Warminster, Yatesbury
GB 20	Air force supply and depots (Luftpark, Nachschublager)	Colerne, Hullavington, Lyneham, Wroughton
GB 22	Ammunition depot (Munitionslager)	Chilmark

Some sheets date their photographs. The Colerne airfield sheet cites a photograph of 30 November 1940, the Zeals sheet one of 21 November 1940, and the Tilshead camp sheet one of 13 December 1940. None of those dates matches a sortie in the Wiltshire photograph list, so the dossiers drew on cover beyond what is catalogued here. The Tilshead and Zeals sheets were reissued in a later, plainer format dated 1941 and 1942.

Catalogue notes

Searching the NARA catalogue by county misses some Wiltshire dossiers, and a few entries need correcting:

• Colerne (GB 10 866 and GB 20 43) is catalogued under Gloucestershire.
• South Marston (GB 10 373) is catalogued under "Berwicksire".
• North Tidworth (GB 14 51) is catalogued under Hampshire.
• Zeals is catalogued under Wiltshire, but its file unit places it in Somerset.
• Boscombe Down has the local identifier GB 10-21. The sheets, the scan file names and the Alton Barnes card all give GB 10 22.
• The Wroughton airfield dossier (GB 10 867, 27 scans) sits under the file unit for Dumfries.
• Chippenham has a file unit in the series but no digitised dossier.

The photograph search covered frames whose catalogue entry names Wiltshire. Frames catalogued under a neighbouring county are not on the map.

Using the map

Photographs are coloured by sortie, in shades of pink from pale (August 1940) to deep (December 1940). Open rings are oblique views. Gold squares are dossiers, lettered by category: A for airfields, C for army camps, S for supply and depots, M for the ammunition depot. Click any point for the record, a preview of the scan and links to the full-size images. The key can switch sorties and categories on and off.

Photograph positions are NARA's frame centres, not footprints. Dossier positions are the coordinates printed on the sheets, to the nearest minute (about ±1 km). Where the sheet could not be read, the position is the station or camp itself.

Sources

• National Archives and Records Administration. German Flown Aerial Photographs, 1939–1945. Record Group 373, Records of the Defense Intelligence Agency, series NAID 306065. catalog.archives.gov/id/306065
• National Archives and Records Administration. Target Dossiers Pertaining to the British Isles, 1938–1945. Record Group 242, National Archives Collection of Foreign Records Seized, series NAID 3371016. catalog.archives.gov/id/3371016
• GX 10004 SG, R, Exposure 95, 4 September 1940. NAID 220881704. catalog.archives.gov/id/220881704
• Target Dossier for Alton Barnes, Wiltshire, England, GB 10-391. NAID 240794047. catalog.archives.gov/id/240794047
• National Archives and Records Administration. RG 373 GX Foreign Aerial Photography (research guide). archives.gov
• National Archives and Records Administration, The Unwritten Record (2019). Researching Foreign Aerial Photography: Captured German Aerial Prints. unwritten-record.blogs.archives.gov
• National Collection of Aerial Photography. German Air Force (GX) collection. ncap.org/image-collection/gx
• Luftwaffedata Wiki. Target Codes. luftwaffedata.co.uk

All images: NARA, listed as Use: Unrestricted. The map uses NARA catalogue data; basemaps © OpenStreetMap contributors, CARTO, Esri and OpenTopoMap.

The Mystery of the Shrinking Barrows

Lidar investigations

Over twenty years, the round barrows on land returned to grass around Stonehenge, much of it National Trust land, appear to have lost height. The average loss is 5 cm, about two inches, and the worst is more than a hand's width. Barrows in neighbouring fields whose use never changed have not moved. Either something is wearing down scheduled monuments in one of the most closely protected landscapes in Britain, or the lidar is being fooled. This post is the investigation.

The LiDAR differences and features can be explored at

https://lidar-lens-public.tim-daw.workers.dev/stonehenge-change/

How it started

Since 2000 most of the arable land in the Stonehenge part of the World Heritage Site has gone back to grass. The National Trust stopped arable farming on its holding that year, and by 2019 more than 526 ha was in permanent pasture (National Trust; National Trust 2019). Map 3 of the 2009 WHS Management Plan dates the reversions field by field from 2000 to 2011. Map 4 of the 2015 plan adds further fields reverted by 2015, without dates (WHS Management Plan 2015).

Two Environment Agency lidar surveys bracket the change. The first was flown on 8 December 2001 (survey P_2053, 1 m last-return DTM), while much of the land was still under the plough. The second is the National LIDAR Programme survey of 4 April 2021. The aim was modest: to see whether faint earthworks had begun to reappear once ploughing stopped. They had not. A search of the reverted ground found five patches of new relief, and all of them are modern, the largest being the turning circle for the visitor buses at SU 1207 4236. The barrows, however, did something else.

The oddity

Each mound was measured the same way in both surveys: a plane fitted to the ground beyond the mound was subtracted, leaving the mound's height above its surroundings. Seven mounds in fields reverted between 2003 and 2007 were on average 0.06 m lower in 2021. Eight mounds in grass since before 2000 had not changed, and nor had 27 that were still arable in 2008. The worst cases were a group of three bowl barrows (NHLE 1009620, −0.15 m), the 2 m bowl barrow north of Springbottom Farm (1009625, −0.11 m) and the long barrow north of Normanton Gorse (1008953, −0.06 m).

Figure 1. Normanton Down, reverted to grass 2003–2007. Left: December 2001. Centre: April 2021. Right: change in local relief, 2021 minus 2001; red = relatively lower now. 1 m grid, σ = 1 m smoothing, hillshade from the NW at 35°.

Figure 2. The control: Old King Barrows and the Avenue, grassland by 2000. Same processing and scale as Figure 1. No systematic change.

A few centimetres is well inside the ±15 cm absolute accuracy quoted for the older Environment Agency surveys, and close to the 0.10 m scatter of a single featureless test point. Before asking what happened to the barrows, the first job was to establish that anything had happened at all.

Ruling out the instrument

Levels. The whole 2021 surface sits higher than the 2001 surface: the median difference on tarmac roads in tile SU1040 is +0.083 m (n = 8,008). Each tile was levelled to its own road offset. Horizontal misregistration is under 0.5 m.

Stripes. The levelled difference map (Figure 3) shows north–south bands with a dominant east–west period of 417 m, the fingerprint of mismatched 2001 flight strips, plus 5–10 cm steps at field boundaries. The 2001 files contain no strip outlines, so the bands were removed empirically. Within each 1 km block of northing, the median difference was taken down each column of stable ground, smoothed over 51 m and subtracted. The correction spans −0.17 to +0.15 m (1st–99th percentile). Stable ground was defined in two ways, long-term grass only and all open fields, to check whether the choice drives the result.

Figure 3. Co-registered difference, 2021 minus 2001, tiles SU1040 and SU1035, 5 m smoothing, ±0.10 m; red = higher in 2021, blue = lower. North–south flight-strip banding and field-shaped steps dominate; woodland and built areas saturate.

Neighbours. Each mound top was compared with a ring of ground 10–30 m beyond its foot, in the same field and within 25 m of the mound in easting, so that any leftover striping affects mound and ring alike.

Decoys. Random points away from monuments, measured the same way, show no change in the reverted fields: −0.002 m (n = 58) and −0.004 m (n = 26).

More barrows. Adding OpenStreetMap tumuli to the scheduled monuments gives 157 measurable mounds in classed fields. After destriping and pairing:

Field history	n	Mound minus ring, mean change (m)	Lower / higher	p
Grass by 2000	58	+0.007	23 / 35	0.15
Reverted 2000–2011 (dated)	47	−0.055	38 / 9	0.00003
Reverted 2008–2015 (undated)	10	−0.007	7 / 3	0.34
Arable throughout	40	0.000	18 / 22	0.64

Two-sided binomial sign test. Long-term grass used as stable ground; using all open fields gives the same −0.055 m (38 / 9) and shifts no other class by more than 0.003 m.

The loss survives every step almost unchanged, and the control classes stay flat. Something real distinguishes the barrows in the early reversions. The later, undated reversions show nothing.

A second site. The best independent coverage is around Avebury, with a 0.5 m survey of May 2006 and National LIDAR Programme cover from winter 2018–19. Only three measurable mounds there lie in fields mapped as reverted, and those reversions are undated. All three are lower, by 0.024 m on average (p = 0.25), which is consistent with Stonehenge but not evidence. Cranborne Chase, the South Downs and the RSPB's Winterbourne Downs offered no field-located reversion, dated after an early survey, with enough mounds to test. Winterbourne Downs began reverting in 2006, after an October 2005 survey (Farm Wildlife 2020), but holds only four barrow listings.

The suspects

Sheep, rabbits and weather. Soil worn from the mounds should end up in the ring ditches. It has not: ring ditches in the 2000–2011 reversions are, if anything, 0.016 m deeper (n = 13, p = 0.58).

Settling fill. On the analogy of a Victorian well, loose ditch fill might compact and sink under grass. There is no sign of this at 1 m resolution, in ring ditches or in 188 transects across linear ditches (+0.006 m, p = 0.94).

Slumping plough soil. Soil heaped at barrow margins by ploughing would drop at the edge, not the top. The loss is greatest at the centre: −0.075 m within half the radius, against −0.024 m at 10–30 m.

Visible vegetation in 2001. The 2001 last-return surface sits about 6 cm above the DTM on mound tops, but equally on grassland mounds that did not shrink and on reverted ones that did. In the reverted classes it does not predict the size of the loss (r = −0.10, p = 0.51), and nor does 2001 ground roughness (r = −0.06, p = 0.68).

The 2001 processing. The striping shows that the 2001 processing left systematic errors, and the metadata name neither the sensor nor the ground filter. The neighbour comparison cancels anything that varies over tens of metres, but not an error that depends on surface type.

Grazing. In December 2001 many of these barrows were uncultivated islands in arable fields. Since reversion the National Trust has run "a tightly managed grazing regime", with many barrows mown or strimmed (National Trust). Island mounds that went to grass lost 0.044 m relative to their surroundings (34 down / 12 up, p = 0.002). Island mounds that stayed in arable did not (+0.005 m). No per-field grazing dates have been found.

The theory

The measurement compares a mound with the ground around it, and only in the early reversions did that contrast change between the flights. In December 2001 the mound carried rough, ungrazed grass and the ground around it was cultivated soil. By April 2021 both were short sward. A mat of dead grass and litter on an ungrazed island would hold the lidar ground surface a few centimetres above the soil on the mound but not on the field around it. The 2001 DSM-minus-DTM test cannot detect such a mat, because the last return and the filtered ground both land on top of it. Grassland mounds (grass all round at both dates) and arable mounds (the same island contrast at both dates) cancel out. Only mounds whose surroundings changed character should change, and that is what the table shows. On this reading the barrows have not shrunk at all. What has gone is the thatch.

Two pieces of evidence point the same way. On Normanton Down (Figure 1) the loss forms halos that enclose groups of mounds along the line of the former uncultivated strips, rather than circles round each mound. In 2021 the point cloud classes fewer returns as vegetation on these mound tops (3.3%) than on long-term grassland mounds (10.5%).

A witness

The barrows in Fargo Plantation, just south of the Cursus, are an independent test outside the reversions. In April 2009 the trees there still prevented a full earthwork survey (Bishop & Amadio 2010). Between the flights the plantation was thinned but left standing, and the vegetation was cleared from the barrows alone, a clearance I witnessed. Every one of those barrows is lower in 2021. Vegetation was removed from the mounds and not from their surroundings, and the lidar records it as lost height.

Loose ends

The later reversions show no loss, possibly because their mostly low mounds were ploughed over rather than kept as islands, or because some of that ground was still cultivated close to 2021: one field mapped as reverted by 2015 carries tramlines 20–25 m apart in 2021. The 13 named barrows of the Normanton Down group lose 0.034 m on average but split only 7 down / 6 up. In a small subsample, mounds reverted in 2007 lost more (−0.106 m, n = 3) than those reverted in 2003 (−0.025 m, n = 3).

Something else in the difference map

The same map holds a second, unrelated signal. West of Stonehenge, the field between the former A344 and the A303 is lower overall in 2021, but narrow strips within it have not changed (Figure 4). They run westward from the stones for a considerable distance, opening into a V, along the lines of former tracks to the monument. Ground compacted by long use as a trackway would settle less than the loosened plough soil around it. The old routes to the stones are recorded in how the ground has settled.

Figure 4. Co-registered difference, 2021 minus 2001, west of Stonehenge; red = higher in 2021, blue = lower, ±0.10 m. Pale east–west strips within the lowered field between the former A344 and the A303 mark ground that has not changed.

The verdict, for now

The signal is real and repeatable. Barrows in fields reverted between 2000 and 2011 measure about 5 cm lower relative to their surroundings in 2021 than in 2001, while barrows in long-term grass and long-term arable do not. The most economical explanation is that the barrows are intact. On the uncultivated islands, the surface the laser took for ground in 2001 lay above the soil, and grazing and clearance have since removed it. This is not yet proven, and an error in the 2001 processing that depends on surface type has not been excluded. Four checks would close the case:

1. Sensor and ground-filter details for the December 2001 flight from the Environment Agency, and from Bewley, Crutchley & Shell (2005), who describe the early lidar survey of the WHS.
2. Aerial photographs from 2000–2003, to map the uncultivated islands and test whether the loss stops at their edges.
3. Per-field grazing and mowing histories from the National Trust, the RSPB and Natural England.
4. A probe measurement of thatch depth on an ungrazed barrow and a grazed one nearby, the cheapest test of the missing 5 cm.

Methods

Environment Agency DTM, 8 December 2001 (P_2053, 1 m), and National LIDAR Programme DTM, 4 April 2021 (1 m), on a common grid with Gaussian smoothing (σ = 1 m). Mound centres were refined on the 2021 survey. A plane fitted beyond radius + 8 m was removed, and values were taken from azimuthally averaged radial profiles. Field histories come from the hand-georeferenced plan maps (15–50 m accuracy). Outside the WHS, Priority Habitat Inventory and CROME 2020–21 were used. Monuments are NHLE scheduled monuments plus OpenStreetMap tumuli.

References and data

• Bewley, R.H., Crutchley, S.P. & Shell, C.A. 2005. New light on an ancient landscape: lidar survey in the Stonehenge World Heritage Site. Antiquity 79(305), 636–647. doi:10.1017/S0003598X00114577
• Bishop, S. & Amadio, L. 2010. Stonehenge World Heritage Site Landscape Project: The Cursus Barrows and Surrounding Area. English Heritage Research Department Report Series 85-2010. Historic England
• Stonehenge and Avebury WHS Steering Committees 2015. Stonehenge, Avebury and Associated Sites World Heritage Site Management Plan 2015. PDF
• National Trust. Our work at the Stonehenge Landscape. nationaltrust.org.uk
• National Trust 2019. Written Representation, A303 Amesbury to Berwick Down (TR010025). PDF
• Farm Wildlife 2020. Case study: reversion of arable land to lowland chalk grassland. farmwildlife.info
• Environment Agency / Defra lidar. Defra Data Services Platform; LIDAR DTM Time Stamped Extents
• Historic England, NHLE scheduled monuments. Data downloads
• Natural England Open Data (Priority Habitat Inventory); RPA Crop Map of England. naturalengland-defra.opendata.arcgis.com
• OpenStreetMap contributors (ODbL), via the Overpass API.

LiDAR Lens for Wiltshire

This post has a companion short film A LiDAR lens for Wiltshire, which shows the Lens at work in two minutes: the sun turning over the field banks in Great Ridge Wood, six ways of drawing the same ground, Stonehenge, and What's here? on a barrow beside it.

Anyone who has walked Wiltshire for long knows the ground is full of lumps and dips that the aerial photographs don't explain. Crops, hedges and trees hide a great deal. LiDAR takes the vegetation away and leaves the bare earth, and the Environment Agency has kindly flown most of the country and made the results free. The snag has always been getting the best from it without a GIS degree and a lot of patience.

So I have built something to make it easier, and it is now open to anyone: the LiDAR Lens for Wiltshire. It is free, there is no login, and it works on a phone as well as a desktop.

What it does

It covers all of Wiltshire and Swindon, about 3,800 km², using the Environment Agency's 1 m LiDAR composite terrain model laid over Esri aerial imagery, with OpenTopoMap as a background map.

The idea is simple. A circular lens sits on the aerial photo, and you drag it about and resize it to see the bare ground underneath. Inside the lens you can choose how the ground is drawn:

• hillshade, lit from a single direction or from several
• slope
• local relief model
• sky-view factor
• red relief

There are controls for sun angle, vertical exaggeration and colour, so you can tease out the faint stuff. Low sun, a bit of exaggeration and a slow sweep across a field is surprisingly addictive.

What’s here?

Click a spot and the "What’s here?" panel gives you plain measurements: local relief, size, elongation and edge slope. It also lists nearby recorded sites from Historic England's open data (scheduled monuments, listed buildings and aerial investigation mapping) and from OpenStreetMap, with links to the records.

Other bits

• Historic OS maps from the National Library of Scotland (25-inch, six-inch and one-inch, roughly 1880s to 1920s) as overlays, handy for comparing old field boundaries and tracks with the ground today
• Wiltshire Council public rights of way
• Go to a grid reference, place name or postcode, or "Use my location" when you're out in the field
• An elevation profile, share links, keyboard shortcuts and a help panel

Please use it responsibly

The public version contains no county Historic Environment Record data but a link to where the data can be obtained from is provided, observing uncertain copyright restrictions. Please respect landowners and stick to rights of way. Never dig or metal-detect on sites; scheduled monuments are protected by law. If you think you have found something new, report it to the Wiltshire HER at archaeology@wiltshire.gov.uk. They would much rather hear about it than have it dug.

Other counties welcome

There is nothing special about Wiltshire here, apart from it being the best county. The code is on GitHub under the MIT licence, and PROTOCOL.md walks through, step by step, how to build the same thing for your own patch. If you fork it for another county, do let me know.

I built it with a good deal of help from Grok Bot, and it is hosted on Cloudflare. It will have bugs and rough edges, so please leave a comment below with feedback, ideas, or anything interesting you spot.

Credits

• LiDAR: Environment Agency, Open Government Licence
• Aerial imagery: Esri
• Recorded sites: Historic England, Open Government Licence
• Historic maps: National Library of Scotland, CC-BY. Reproduced with the permission of the National Library of Scotland
• Public rights of way: Wiltshire Council, Open Government Licence; contains OS data. This is not the legal Definitive Map
• Map data © OpenStreetMap contributors
• Background map: OpenTopoMap, CC-BY-SA

Notes on the film

Every shot is a screen capture of the public LiDAR Lens, made frame by frame with the viewer's own controls, so what the film shows is what the site shows. Places: Great Ridge Wood (field banks under the trees), West Woods near Lockeridge, Stonehenge, and the disc barrow 220 m south-west of Stonehenge (NHLE 1012385). The background throughout is the National Library of Scotland's six-inch Ordnance Survey map (one-inch for the county view), reproduced with the permission of the National Library of Scotland (CC-BY). LiDAR: Environment Agency LIDAR Composite DTM 1 m (OGL). Music: original.

81 degrees at Stonehenge

This post is the companion to the short film 81 degrees at Stonehenge. It sets out why two stones at the centre of the monument are turned off the solstice axis, how far, and how the angle can be laid out with a single straight line. The evidence, numbers and caveats follow.

The axis

Stonehenge's main axis runs from the midsummer sunrise in the north-east to the midwinter sunset in the south-west, through the entrance gap between Stones 30 and 1. The reference value used here is the geometrical axis of the trilithon horseshoe, 49.95° true (49.81° on the National Grid; Thom et al. 1974), which Ruggles takes as the best estimate (49.8° ± 0.2°). Most of the stones at the centre are set square to it. Two are not.

Plan of the standing stones with the solstice axis. Stone positions from T. Daw's 3D model; Stone 56 from the Rees 1989 survey.

The Altar Stone

Atkinson (1956) noted that the Altar Stone, the recumbent green sandstone slab at the centre, does not lie at right angles to the axis. Gordon and Phyllis Freeman (2001) observed that its twist lines it up with the midwinter sunrise. Simon Banton later ran the same line through a tooled notch in Stone 58 and along the edge of Stone 53, and found it ran along the centre line of the Altar Stone. Parker Pearson et al. (2024) describe its long sides as "aligned approximately on the midwinter sunrise".

Most of the Altar Stone lies under the fallen Stone 55 and lintel 156, so modern surveys show only small exposed patches. The two plans that draw its whole outline, Petrie's (1880) and Atkinson's plan of his cutting 53 (Cleal et al. 1995, Fig. 286), put its long axis at about 82–83° to the solstice axis, each to about ±1.5°. The film calls it "near 81°".

The Altar Stone against a square-set line. Outline schematic.

Stone 56 and the Great Trilithon

Stone 56, the tallest stone at Stonehenge and the surviving upright of the Great Trilithon, is turned the same way. The twist was first noted on sarsen.org in June 2012 and published in 2015 as "about 80°" to the axis, a skew of about 10° (Daw 2015). Stone 56 was leaning badly in 1901, and William Gowland excavated around it while it was straightened. His record shows it was reset in its original position, and his excavation of the socket of the fallen Stone 55 showed how its partner had stood:

"If set back in its place thus indicated the 'recumbent stone' would be exactly in line with the 'leaning stone.'" (Gowland 1901)

The recumbent stone is 55; the leaning stone is 56. The whole trilithon, not one stone, was set on the twisted line.

W. Gowland, "Plan of the excavations around the stone", Archaeologia 58 (1902), Fig. 7. Public domain.

Three surveys of Stone 56

Stone 56 is wedge-shaped at ground level. Its inner (north-east) face is rough and stands roughly square to the axis; its back (south-west) face is straight, and it is the back face that the midsummer sun sets along. The back face was measured on three independent surveys, each outline digitised and a straight line fitted to the middle 60–70% of the face:

• Gowland's 1901 excavation plan (1902, Fig. 7), oriented by its drawn north arrow: 80.0–80.7°.
• M. J. Rees & Co. for English Heritage, 1:200 on the National Grid, 1989: 82.0°.
• The English Heritage laser scan of 2011 (Abbott & Anderson-Whymark 2012, Fig. 1): 80.1°.

The mean of the three is 80.8°, each figure good to about ±1–1.5°. Two further plans, not independent of these, give 80.5° (Cleal et al. 1995, Plan 2) and 81.4° (Field et al. 2015, Fig. 2). A stone set square to the axis would read 90°.

The three independent outlines of Stone 56 and their back-face lines. Gowland's outline is placed nominally on the Rees centroid; its angle is unaffected.

Stone 56 as surveyed in 1989, its back face extended, at 81° to the axis

Not just two stones

Other features at the centre follow the same twisted line (Daw 2015). Two postholes north-east of the Altar Stone, 3362 and 3364, mark a pair of wooden posts set on it. At the south-western end of the inner bluestone horseshoe, the pair of bluestone pillars 66 and 68 (68 now pushed over, its original position known from Gowland's records) define the end of the horseshoe on the same alignment. The outer bluestone circle, badly damaged near the axis and largely unexcavated, appears to be twisted the same way. None of these on its own proves the twist was deliberate; together they show it was not confined to one stone.

The sky in 2500 BC

The direction of sunrise at a solstice depends on the latitude and on the tilt of the earth's axis, which changes slowly. For Stonehenge (51.18° N) in 2500 BC, with the obliquity of the ecliptic at 23.973° (Vondrák et al. 2011), the midsummer sun rose at 49.6° and the midwinter sun at 130.4°, on a level horizon. The two sunrises were 80.8° apart. The same angle separates the two sunsets, and so the main axis (midsummer sunrise to midwinter sunset) and the second solstice line (midwinter sunrise to midsummer sunset) cross at 80.8°. A horizon altitude of 0.6° changes this by only 0.02°. The angle depends mainly on the date: it was 80.6° in 2000 BC and is 78.8° today. Simon Banton's figure for 2500 BC is 80° 49′ 25″.

The Altar Stone and Stone 56 lie along the second line. Seen from inside the circle, the midsummer sunset runs down the back face of Stone 56; it was photographed there in 2014, 2015 and 2022. The midwinter sunrise no longer reaches that direction, so Banton (2026) photographed the major-standstill moonrise of 2024–25 in its place, through the notch in Stone 58 and along the Altar Stone.

The four solstice directions at Stonehenge, 2500 BC. Diagram, level horizon.

 

Midsummer sunset beside Stone 56. Photo: T. Daw, 2015.

The clock face

The outer sarsen circle had 30 uprights and 30 gaps. Taking the centres of both gives sixty equally spaced marks round the circle, like the minutes on a watch (Daw 2024). Set the main axis from 12 (midsummer sunrise) to 6 (midwinter sunset). The entrance gap is at 12, so the stones fall on the odd minutes and the gaps on the even ones.

A straight line from the 15-minute mark to the 42-minute mark crosses the axis at exactly 81°. The geometry is simple: a chord between marks a and b is perpendicular to the radius through their midpoint, so it lies at 3(a + b) + 90 degrees to the axis, modulo 180. For 15 + 42 = 57, that is 81°. Any chord whose ends add to 57 is parallel to it.

The sixty-mark circle, the axis from 12 to 6, and the 15–42 line at 81°. The Altar Stone and Stone 56 are drawn parallel to the line: schematic.

The gaps matter. Chords between stone centres alone come out in steps of 6°, so the nearest to 81° are 78° (15 to 41) and 84° (15 to 43). Only with the gaps counted does 81° fall out. A sixty-mark circle can make any multiple of 3° with one chord, so 81° is easy to set out rather than forced by the circle; the case is that it is easy and it matches the sky.

Stones only: 78° and 84°. Stones and gaps: 81°.

The Bush Barrow lozenge

The gold lozenge from Bush Barrow (Wilsford G5), on Normanton Down about a kilometre south-west of Stonehenge, was dug by William Cunnington for Richard Colt Hoare in 1808 and is now in the Wiltshire Museum, Devizes. It is a sheet of gold 184 × 156 mm, from a burial of about 1950 BC, some five centuries after the sarsens went up. Thom, Ker and Burrows (1988) measured the acute angles of its diamond at 81° and noted that this was the angle between the midsummer and midwinter sunrises at the latitude of Stonehenge (MacKie 2009). The Wiltshire Museum's own page gives 80°.

The Bush Barrow gold lozenge, Wiltshire Museum, with its acute angle marked "about 81°" (the published figure; the photo is taken at an angle through display glass and is not a measurement). Photo: Pasicles, CC0, via Wikimedia Commons.

Caveats

• The Altar Stone may once have stood. Atkinson (1956) and Cleal et al. (1995) left open that it was a fallen upright. Burl (2006) and Parker Pearson et al. (2024) favour a deliberate recumbent; Burl put the chance of a fallen upright landing on the solstice line at about 1 in 165. It is not settled by excavation.
• Precision. Ruggles (1997) warns that Stonehenge's near horizon does not justify alignment claims finer than about 1°. The angle here is a ground layout, not a horizon sighting, and Stone 56's back face is measured to about ±1–1.5° on each survey. The Altar Stone is near 81°, not measured to a degree.
• The lozenge is later. A shared angle on a craft object of c. 1950 BC is suggestive, not proof of shared knowledge.
• Sixty marks is a circle, not a number system. There is no evidence of base-60 counting in Neolithic Britain. That the builders used the 15–42 chord is a hypothesis; the geometry and the sky angle are not.
• Not the same as the calendar theory. Darvill (2022) proposed that the sarsens encode a solar calendar; Magli and Belmonte (2023) rejected it. The clock-face reading here is about angles, not days.

Notes on the film

• The plan of the standing stones comes from T. Daw's 3D model of Stonehenge. The orientations of Stone 56 and the Altar Stone in that model were set from the Twisted Trilithon paper, so they are not used as evidence: Stone 56 is drawn from the Rees 1989 survey outline, and the Altar Stone is marked as schematic.
• On the clock-face diagrams the Altar Stone and Stone 56 are placed at their plan positions and drawn parallel to the 81° line, as an illustration.
• Sun positions are for 2500 BC on a level horizon, for the centre of the disc.

Sources

• Abbott, M. and Anderson-Whymark, H. 2012. Stonehenge Laser Scan: Archaeological Analysis Report. English Heritage Research Report Series 32-2012.
• Atkinson, R. J. C. 1956. Stonehenge. London: Hamish Hamilton.
• Banton, S. 2026. The secondary solstice axis at Stonehenge: using the Moon as a proxy for the ancient Sun. Journal of Skyscape Archaeology, 133–141. doi:10.1558/jsa.33686
• Burl, A. 2006. Stonehenge: A New History of the World's Greatest Stone Circle. London: Constable.
• Cleal, R. M. J., Walker, K. E. and Montague, R. 1995. Stonehenge in its Landscape: Twentieth-century Excavations. English Heritage Archaeological Report 10.
• Darvill, T. 2022. Keeping time at Stonehenge. Antiquity 96: 319–335. doi:10.15184/aqy.2022.5
• Daw, T. 2015. The Twisted Trilithon of Stonehenge. Wiltshire Archaeological and Natural History Magazine 108: 15–24.
• Daw, T. 2024. Sexagesimal Stonehenge: the geometry of the Stonehenge sarsen trilithons. doi:10.13140/RG.2.2.16275.86560
• Daw, T. 2025. The geometry of the horseshoe stones at Stonehenge. doi:10.13140/RG.2.2.23505.65127
• Field, D. et al. 2015. Analytical surveys of Stonehenge and its environs, 2009–2013: Part 2, the stones. Proceedings of the Prehistoric Society 81: 125–148. doi:10.1017/ppr.2015.2
• Freeman, G. R. and Freeman, P. J. 2001. Observational archaeoastronomy at Stonehenge: winter solstice sun rise and set lines accurate to 0.2° in 4000 BP. In J.-L. Pilon, M. W. Kirby and C. Thériault (eds), A Collection of Papers Presented at the 33rd Annual Meeting of the Canadian Archaeological Association, 200–219.
• Gowland, W. 1901. The recent excavations at Stonehenge, with inferences as to the origin, construction, and purpose of that monument. Abstract of a report presented to the Society of Antiquaries, 19 December 1901. Man.
• Gowland, W. 1902. Recent excavations at Stonehenge. Archaeologia 58: 37–118. doi:10.1017/S0261340900008882
• MacKie, E. W. 2009. The prehistoric solar calendar: an out-of-fashion idea revisited with new evidence. Time and Mind 2: 9–46. doi:10.2752/175169709X374263
• Magli, G. and Belmonte, J. A. 2023. Archaeoastronomy and the alleged "Stonehenge calendar". Antiquity. doi:10.15184/aqy.2023.33
• M. J. Rees & Co. 1989. Stonehenge survey, 1:200, drawing AS16/1, for English Heritage. Historic England Archive MP/STO0861.
• Parker Pearson, M. et al. 2024. Stonehenge and its Altar Stone: the significance of distant stone sources. Archaeology International 27: 113–137. doi:10.14324/AI.27.1.13
• Petrie, W. M. F. 1880. Stonehenge: Plans, Description, and Theories. London: Stanford.
• Ruggles, C. 1997. Astronomy and Stonehenge. In B. Cunliffe and C. Renfrew (eds), Science and Stonehenge. Proceedings of the British Academy 92.
• Thom, A. et al. 1974. Stonehenge. Journal for the History of Astronomy 5: 71–90.
• Thom, A. S., Ker, J. M. D. and Burrows, T. R. 1988. The Bush Barrow gold lozenge: is it a solar and lunar calendar for Stonehenge? Antiquity 62: 492–502. doi:10.1017/S0003598X00074597
• Vondrák, J., Capitaine, N. and Wallace, P. 2011. New precession expressions, valid for long time intervals. Astronomy & Astrophysics 534: A22.

Earlier posts on sarsen.org: Twisted Stone 56 (2012); The Twisted Trilithon of Stonehenge (2015); Sexagesimal Stonehenge (2024); Stonehenge clockface solstitial alignments (2025); Visualising the secondary solstice axis (2026).

The Boles Barrow bluestone

This post is the companion to the short film The Boles Barrow bluestone: a 400 kg exotic in Salisbury Museum, the claim that it came from a long barrow older than Stonehenge, and why every link in that claim breaks.

An exotic, not an erratic

The stone at the British Museum, 2022 · T. Daw

The boulder is Preseli spotted dolerite (Thomas, in WAM 1924; Thorpe et al. 1991), now Salisbury Museum SBYWM:1934.68. On Salisbury Plain it is an exotic: a rock lying far from its geological source, however it got there. An erratic is an exotic moved by a natural agent, usually glacial ice; every erratic is an exotic, but not every exotic is an erratic. Whether this one is an erratic depends on how it reached the Plain, and the evidence for that is where it was first found: in a long barrow older than Stonehenge, or at Stonehenge itself.

Why it matters

Boles Barrow, Environment Agency LiDAR 1 m (2022), silver hillshade, low sun from the north-west · OGL v3.0

Boles (Bowls) Barrow, ST 94204 46771, is a long barrow 18.6 km west of Stonehenge. Five of its thirteen primary burials have been dated, the latest to 3760–3630 cal BC (Parker Pearson et al. 2015). Stonehenge's first bluestones were set up about 3000 BC. A bluestone buried in the barrow would put bluestone on the Plain centuries before Stonehenge, and since Thorpe et al. (1991) the stone has been cited as evidence that glaciers, not people, carried the bluestones east. In 2015 Parker Pearson and colleagues thought a Boles Barrow origin "highly probable"; in 2020 Parker Pearson and Richards concluded it "cannot be the Boles Barrow stone". The British Museum's 2022 label hedged: "Boles Barrow or Stonehenge".

The dig is in the archive

Colt Hoare, Ancient Wiltshire I (1812), Heytesbury Station III · photo T. Daw

William Cunnington opened the barrow in 1801. His letter to H. P. Wyndham of 18 July 1801, known from a copy in his daughter Elizabeth's hand, describes "a ridge of large stones and flints" over the burials; a footnote in his own hand gives their weight: "from about 28lbs. to 200 lbs." The letter calls them "of the same species of Stone as the very large Stones at Stonehenge … what the Country people call Sarsens". No bluestone is mentioned, and Colt Hoare's account (1812, pp. 87–88) has none either. The digs of 2023 and 2024 found no bluestone (The Past, 27 May 2023).

Too big

Salisbury Museum, 2012 · T. Daw

Wyndham, writing to Colt Hoare in 1802, described the same stones as "from 28lbs. to 200lbs. in weight", "similar in substance to many at Stonehenge and … often found peeping out from the turf or just under it, in the vallies of our downs like those near Abury". These are local sarsens of 13 to 91 kg. Published weights for the bluestone boulder run from 340 kg (Williams-Thorpe & Thorpe 1992) to 611.64 kg (Salisbury Museum label, 2012); the film says "around 400 kg".

An undated note

The only link is a second footnote in Cunnington's hand on the copy of the letter. As printed in 1924: "Since writing the above I discover among them the Blue hard Stone also, ye same to some of the upright Stones in ye inner Circle at Stonehenge." The first printing, in 1922, reads "I discovered amongst them the Blue hard Stone, ye same as the upright Stones in ye inner Circle at Stonehenge", and its editor, B. Howard Cunnington, thought it "possible that after the letter to Mr. Wyndham was sent, the foregoing note was added as a memorandum". A second copy of the letter carries the footnote mark but no note. The note gives no date and no size.

Matched in 1923

Salisbury Museum, 2016 · T. Daw

The boulder was connected to the note 122 years after the dig. In 1923 B. Howard Cunnington searched William Cunnington's old garden in Heytesbury and found three sarsens and a Dartmoor granite block, "but no 'Blue Stone'". Lord Heytesbury then found a bluestone under a beech tree at Heytesbury House. His aunt, the Hon. Mrs Hamersley, recalled that "the stone was removed from the late Mr. Wm. Cunnington's garden at Heytesbury to its present site at Heytesbury House before 1860. It was called the 'Stonehenge Stone'." On that account and Dr H. H. Thomas's identification of the rock, B. Howard Cunnington concluded that "there can be little doubt" it was the Boles Barrow stone, explaining its name as arising "from its similarity to the Blue Stones". An 1864 family letter records that another stone in the same garden had been wrongly "supposed … a stone brought from Stonehenge".

Where Colt Hoare did find bluestone

Colt Hoare (1812), p. 127

Colt Hoare did record bluestone when he found it. Amesbury No. 16, near Stonehenge, was "a mutilated flat barrow, 76 feet in diameter", a round barrow whose primary burial was a cremation in a cist with "a spear head of brass in fine preservation, and a pin of the same metal": a Bronze Age burial, later than Stonehenge. Over the cist "we found a large piece of one of the blue stones of STONEHENGE", which, he wrote, "decidedly proves that the adjoining temple was erected previous to the tumulus". On the same page he noted that the sarsen pieces in the barrow were "chipped off, (I am sorry to say) like those now daily knocked off from the great fallen trilithon".

(Boles Barrow) Stonehenge Bluestone 2016 by Adam-Stanford - ASGS on Sketchfab

Notes on the film

Every link between the boulder and Boles Barrow breaks: it was not recorded at the dig; it is several times heavier than the stones that were; the note that mentions a "Blue hard Stone" is undated and gives no size; and the boulder was matched to the note only in 1923, at another house, where it was known as the Stonehenge Stone. It is much more likely to have been obtained from Stonehenge, by whom and when is not known: it may have left the monument centuries before Cunnington, when stone was being taken from it. If so, it is no evidence for glacial transport of bluestones to Salisbury Plain. Accounts of its surface differ: "certainly has been dressed" (1924), "appears unworked" (1992), parts "worked down with metal tools" (Parker Pearson & Richards 2020). The note is quoted from its printed versions; the manuscript has not been re-examined. Photographs: T. Daw. Map: contains OS data © Crown copyright and database right 2026 (OS Terrain 50, Open Rivers, Open Names). LiDAR: contains Environment Agency data, © Environment Agency copyright and/or database right 2022, Open Government Licence v3.0. Music: original. Earlier posts: The Bowls Barrow Bluestone in Salisbury Museum (2012), The Bowls or Boles Barrow Bluestone – a Red Herring (2016), The Boles Barrow Bluestone (2022), Colt Hoare's description (2022), Did Cunnington find any bluestone in Boles Barrow? (2024).

Sources

British Museum 2022. The world of Stonehenge, exhibition label and large-print guide, p. 38.

Colt Hoare, R. 1812. The Ancient History of Wiltshire, vol. I, pp. 87–88, 127.

Cunnington, B. H. 1922. "Blue hard stone, ye same as at Stonehenge," found in Boles [Bowles] Barrow (Heytesbury, I.). Wiltshire Archaeological and Natural History Magazine 41, 172–174.

Cunnington, B. H. 1924. The "Blue Stone" from Boles Barrow. Wiltshire Archaeological and Natural History Magazine 42, 431–437.

Parker Pearson, M. et al. 2015. Antiquity 89.

Parker Pearson, M. and Richards, C. 2020. The Stonehenge bluestones. In M. Parker Pearson et al., Stonehenge for the Ancestors, Part 1. Leiden: Sidestone, p. 174. doi:10.59641/x8a4u5v6w7

The Past 2023. The latest from the past: Re-excavating Boles Barrow. 27 May. the-past.com

Thorpe, R. S. et al. 1991. Proceedings of the Prehistoric Society 57.

Williams-Thorpe, O. and Thorpe, R. S. 1992. Geochemistry, sources and transport of the Stonehenge bluestones. Proceedings of the British Academy 77, 133–161.

Is Stonehenge a henge?

"Did you know Stonehenge isn't actually a henge?" By the archaeological definition, that's correct. The more interesting question is where the word came from. This page is the companion to the short film Is Stonehenge a henge?

The definition

T. D. Kendrick coined "henge" in 1932 as a class name, taken from Stonehenge. As an archaeological type, a henge is a round earthwork "in which a ditch was dug to make a bank, which was thrown up on the outside edge of the ditch" (Pitts 2001, 26–28): ditch inside, bank outside. Stonehenge's own neighbours fit it. Durrington Walls is "surrounded by a ditch up to 17.6m wide and an outer bank", and Woodhenge has an outer bank "up to 10m wide" (Historic England, List entry 1009133).

Stonehenge reverses it. "The ditch of the enclosure is flanked on the inside by a high bank and on the outside by a low bank, or counterscarp" (Encyclopaedia Britannica). The monument that gave the class its name fails the class's test.

A henge: ditch inside, bank outside. Diagram, not to scale. 

Click pictures to embiggen

Stonehenge: main bank inside the ditch, low bank outside. Diagram, not to scale.

The name

The earliest record is Henry of Huntingdon's, c. 1130, listing the wonders of England: "Secundum est apud Stanenges; ubi lapides mirae magnitudinis in modum portarum elevati sunt, ita ut portae portis superpositae videantur". In translation: "The second is at Stanenges, where stones of wonderful size are raised like doorways, so that doorways seem set on doorways."

The usual reading splits the name into Old English stān, "stone", and hengen, "something hung": a gallows, or stones hung in the air. Stukeley (1740, ch. II) took both views: "Stonehenge is a stone gallows, called so from the hanging parts, architraves, or rather imposts", and "pendulous rocks are now called henges in Yorkshire… Stonehenge in Saxon signifies the hanging stones."

John Hines (2025) takes hengen in its dominant Old English sense. The Dictionary of Old English records one instance meaning "hanging"; the rest refer to "the cross or rack used for torture", and the word glosses ergastulum, a house of correction. He reads the name as "stone prison".

A hanger?

A third candidate is the downland word for a wood on a slope. Old English hangra is "a wood on a hill-side" (Bosworth–Toller), and it survives as hanger. Gilbert White's Selborne had "a long hanging wood called the Hanger. The covert of this eminence is altogether beech" (White 1789, Letter I). The same word gives Hanger Hill and Hanger Lane in Ealing. Related words across the North Sea mean "slope": Middle Low German hanc and Middle Dutch hangende.

The obvious objection is spelling. The early forms (Stanenges, Stanheng, Stanhenge) have no r. But Old English also had henge-clif, "a steep, precipitous cliff; præruptum" (Ælfric's Glossary; Bosworth–Toller), a henge- word for steep ground with no r at all.

Stonehenge sits on the brow of a gentle slope, with the hanger wood of Luxenborough plantation beside it. Read as a "stone hanger", the name describes where it stands, as the hanger woods of the Downs are named for where they grow (Daw 2016). That remains a suggestion. Hengen, in one sense or another, is the usual reading.

Stonehenge with the hanger wood behind.

Caveats

• "Henge" as a class is a 20th-century convention; the builders did not share it.
• The film's section diagrams are schematic and not to scale.
• The cognates come from Wiktionary's etymology for hangra and still need checking against a printed etymological dictionary.
• Music: original.

Sources

• Bosworth, J. & Toller, T. N. An Anglo-Saxon Dictionary: hangra; henge-clif.
• Henry of Huntingdon, Historia Anglorum (c. 1130). Latin as quoted in S. Ferguson, "On a passage in the Historia Anglorum of Henry of Huntingdon relative to Stonehenge", Proceedings of the Royal Irish Academy 9.
• Hines, J. 2025. Anglo-Saxon Stonehenge. Early Medieval England and its Neighbours 51. Cambridge Core
• Historic England, List entry 1009133: Henge monuments at Durrington Walls and Woodhenge.
• Kendrick, T. D. & Hawkes, C. F. C. 1932. Archaeology in England and Wales 1914–1931. London: Methuen.
• Pitts, M. 2001. Hengeworld. London: Arrow.
• Stukeley, W. 1740. Stonehenge, a Temple Restor'd to the British Druids. London.
• White, G. 1789. The Natural History and Antiquities of Selborne. London.
• Encyclopaedia Britannica, "Stonehenge".

Earlier post: Stonehenge – What does "Henge" mean, why is it a "Henge"? (9 December 2016)

The road under the rampart: a Roman road, Bokerley Dyke and Pitt-Rivers' Section 5

This post is the companion to the short film The road under the rampart. A recent claim holds that the Roman road across Cranborne Chase, locally called Ackling Dyke, began as a prehistoric route. Despite the name it is a road on a raised bank, not a boundary dyke; the dyke in this story is Bokerley Dyke, which cuts across it. The film tests that against the 1 m LiDAR and against the section General Pitt-Rivers cut where the road meets Bokerley Dyke in 1888–90. The evidence, with the quotations in full, follows.

The claim

In a series of 2026 posts on prehistoric-britain.co.uk, R. J. Langdon argues that Ackling Dyke, as the road is locally called, is "a multi-phase transport network rather than a single Roman construction", possibly a water-assisted corridor from a time of higher prehistoric water levels, which the Romans rebuilt and resurfaced. He accepts that "we cannot yet say that the earliest Ackling feature was definitely a prehistoric canal". The argument rests on changes in the size and form of the bank along its length, on its relation to palaeochannels and pits, and on a reading of Pitt-Rivers. A second post, on Puddletown Forest north-east of Dorchester, makes the general point that "metalling is a construction technique, not a chronological marker", and that "the Roman-road interpretation still needs proof".

The road on the downs

The road from Old Sarum to Badbury Rings runs on a raised bank, the agger, which the RCHME recorded as 40 to 50 ft wide and 4 to 6 ft high where best preserved (RCHME 1975). On the Environment Agency 1 m terrain model, north-east of the Dorset Cursus, the bank stands 0.4 to 1.25 m above the ground beside it along 93% of a 4.1 km trace.

The Roman road (Ackling Dyke) north-east of the Dorset Cursus. EA LIDAR Composite DTM 1 m, silver-sun shading. 

Click pictures to embiggen

The bank goes up and over the chalk. Traced along its crest from the point where it crosses the Dorset Cursus, it rises from 77.6 m OD to 115.4 m on Bottlebush Down within 1.1 km, falls to 87.1 m at 2.35 km and climbs again to 117.4 m at 4.1 km. A bank that rises and falls by 30 to 38 m across interfluves cannot have carried water along its length.

Crest of the road bank from the Dorset Cursus north-east for 4.1 km. Height exaggerated as marked.

The road is younger than the barrows it crosses. On Oakley Down the agger "cuts two disc barrows (Wimborne St. Giles (106) and (111)) on the edge of a large group there" (RCHME 1975). On the LiDAR the ring ditch of one stops at the bank, which runs on unbroken. That places the road after the Early Bronze Age, which is a weak bound on its own, but it is the clearest superposition visible from the air.

Oakley Down: the road bank and the edge of the barrow cemetery. Ringed: a disc barrow whose ditch stops at the bank.

Pitt-Rivers at Bokerley

Between 1888 and 1890 Pitt-Rivers cut a series of sections at Bokerly Junction, where the road meets Bokerley Dyke, and published them in the third volume of Excavations in Cranborne Chase (1892). The key to his plates states that "the position of each object was fixed with a spirit-level". He dated the dyke by the coins in and under it, and concluded that it was "thrown up no earlier than the reign of Honorius, a.d. 395-423" (p. 20).

View of Section 1, Bokerly Dyke, looking south-west towards Woodyates. Pitt-Rivers 1892, p. 73.

His Section 4 across the road, away from the Romano-British settlement at Woodyates, shows the road "in its most perfect state": six courses on the old ground surface, "(1) surface mould, 5 inches; (2), gravel with rounded pebbles … 6 inches; (3), rammed chalk rubble, 6 inches; (4), tertiary gravel again, 10 inches; (5), rammed chalk, 6 inches; (6), a single layer of nodular flints, laying on the old surface line. The total height from the old surface line, to the top of the road was 3 feet" (p. 74).

The six courses of Section 4. Diagram from Pitt-Rivers 1892, p. 74.

Section 3, beside the settlement, is different: "The fragments of New Forest ware, and of nails, and a glass bead in the bank of Section 3, shows that the ground must have been occupied to some extent before the road was made" (p. 74). New Forest ware is late Roman. On Pitt-Rivers' own reading, the road bank there was built, or rebuilt, late in the Roman period.

Section 5

Section 5 was cut "across Bokerly Fore and Rear Dykes, along the line of the centre of the Roman Road" (Plate CLXXI). Read from the bottom up:

1. An earlier line of the dyke, the Rear Dyke, was dug and then filled in. In the filling, below the road, lie a coin of Carausius (AD 287–293), a coin of Valens (AD 364–378) and red Samian ware.
2. "The lowest strata, consisting of a pavement of nodular flints, is shown overlaying the filling of the Rear Dyke behind" (p. 91). The road surface here was laid after AD 364. In Pitt-Rivers' words, this was "proving that the Roman Road was used after the Rear Dyke was filled in" (p. 21).
3. Above the road lies a layer of black mould with coins of Helena, Constantius II, Septimius Severus and Gratian (AD 375–383).
4. The later Fore Dyke, the second line of Bokerley Dyke, cut the road, and its rampart was thrown over the road's three lowest courses: "The Roman Road must have existed before the Dyke was made, and must have been cut through to form the ditch of the Dyke, and the earth thrown up over the road to form the rampart" (p. 70).

Section 5 across Bokerly Fore and Rear Dykes, along the line of the centre of the Roman road. Pitt-Rivers 1892, Plate CLXXI (University of Michigan copy).

Langdon quotes Pitt-Rivers' caution that "it does not follow that the Roman Road was made after the Rear Dyke was filled in, as it may have been dug across, and the road afterwards laid again over the filling of the ditch" (p. 21). In context the sentence allows the road to be older than the Rear Dyke, itself a late Roman work. It says nothing about a road before the Roman period.

The order of events

Pitt-Rivers called the two lines of Bokerley Dyke at the junction the Rear Dyke (the first) and the Fore Dyke (the later). Read from the oldest:

1. Bronze Age disc barrows on Oakley Down: the road bank cuts two of them (RCHME 1975).
2. The Roman road: built after the barrows; when is not tested by these sections.
3. The first line of Bokerley Dyke (Rear Dyke): dug and later filled in; the latest coin in the filling is of Valens, AD 364–378. Whether its ditch cut an existing road is left open by Pitt-Rivers ("it may have been dug across", p. 21).
4. The road resurfaced: its flints laid over the filled ditch, after AD 364.
5. The later line of Bokerley Dyke (Fore Dyke): its ditch cuts the road and its bank covers the road's lower courses; Pitt-Rivers dates the dyke no earlier than Honorius, AD 395–423 (p. 20).

The Dorset HER's later phasing of Bokerley Dyke (after Rahtz 1961) appears to describe the same sequence: a "B" Dyke, shortly after AD 364, "cuts through the Badbury–Old Sarum Road" and "the road was restored over it very soon afterwards"; a "C" Dyke, after AD 393–5, cut the road again, "and this time remained cut" (MDO5932).

Conclusion

Every dated relationship puts the road in the Roman period: it cuts Early Bronze Age barrows; beside the Woodyates settlement its bank contains late Roman pottery; at Bokerly Junction it was resurfaced across a ditch filled after AD 364 and then cut by a dyke later still. No dated layer places any phase of the road before Rome. The sections date the road's use and repair, not its first construction, and they come from the Bokerley end; the LiDAR trace covers 4.1 km of the downs. A prehistoric origin would need a dated deposit sealed beneath the primary agger. None has been reported.

Langdon is right that metalling alone dates nothing. Section 5 is the kind of evidence his argument asks for: road metalling with coins sealed beneath it. It answers for the Old Sarum–Badbury road at Bokerley. The stretch he examines in Puddletown Forest, on the road from Badbury Rings to Dorchester, has no dated finds in the Dorset HER (MDO47865): a section at Thorncombe Wood found gravel laid on the old ground surface, wheel ruts and no side ditches. There the road's date rests on its line and form, and dated sections would settle it.

Notes on the film. The LiDAR images use the Environment Agency LIDAR Composite DTM at 1 m (2022), shaded with a low north-west sun. The profile is traced along the crest of the bank on the same data. The diagrams of Section 5 and of the road's courses are redrawn and simplified from Pitt-Rivers' Plates CLXXI and CLXIII and p. 74, with heights exaggerated as marked. Plates from the University of Michigan copy of the 1892 volume. The code is in the film's folder on GitHub (make_assets.py). Music: original.

Sources

• Langdon, R. J. 2026. Ackling Dyke Part II: Puddletown Forest; Ackling Dyke at Woodyates: Part III; Ackling Dyke – Facts and the Archaeological Fiction. prehistoric-britain.co.uk.
• Pitt-Rivers, A. H. L. F. 1892. Excavations in Cranborne Chase, near Rushmore, on the borders of Dorset and Wilts, vol. III: Excavations in Bokerly and Wansdyke, Dorset and Wilts, 1888–1891. Privately printed. archive.org.
• Rahtz, P. A. 1961. Excavations on Bokerley Dyke in 1958, in advance of road widening. Archaeological Journal 118, 65–99 (as cited by the Dorset HER; title not checked).
• RCHME 1975. An Inventory of Historical Monuments in the County of Dorset, Volume V: East Dorset. HMSO.
• Dorset Historic Environment Record: MDO5932 Bokerley Dyke; MDO5591 Ackling Dyke, Gussage All Saints; MDO5640 Ackling Dyke, Gussage St Michael; MDO47865 Roman road from Badbury Rings to Dorchester.

LiDAR: Environment Agency LIDAR Composite DTM 1 m, 2022. © Environment Agency copyright and/or database right 2022. Open Government Licence v3.0.