Thornborough Henges and the Ure-Swale Monuments
Assessing Evidence of Geospatial Intelligence in the Neolithic


Jan. 17, 2007 - Inquiry into the geospatial relationships of the Thornborough Henges (to each other and to other Neolithic monuments in the greater viewscape and surrounding landscape) evidences a large regional pattern of monument placement and knowledge of the true scale of the earth. Additional evidence implies accurate astronomy and heliocentric understanding of celestial motions. Results are discussed in greater detail below, after description of the major monuments considered in the study. Study is ongoing and updates follow below.

Google Earth Placemarks kmz file: neolihic_calc.kmz

Oct. 12, 2006 - Thornborough Henges are foci in the struggle to defend and preserve ancient sites and their environs from destructive modern developments. Quarrying at Thornborough has already destroyed adjacent areas to the west and north of the henges, and quarry expansion is again sought. Because the immediate landscape around the Thornborough Henges remains threatened, I've renewed focus on the Ure-Swale Neolithic monuments, acquired more accurate coordinate data, and expanded study with additional monuments.

The large henges on the Vale along the Ure and Swale Rivers were included in my preliminary study, The Possible Geodetic Properties and Relationships of Neolithic Monuments of the British Isles (2000). Herein, I describe the complex of late Neolithic henges and related placemarks and discuss their geodetic relationships and new findings. A previous page, neolithic.html, provides additional introductory materials as do my Archaeogeodesy pages.

Thornborough Henges
Among the Late Neolithic henges constructed about five millennia ago,
the complex of the three large henges at Thornborough is pre-eminent.
The immediate environs destroyed by quarrying are dark shaded.

Sites Considered

Thornborough Henges. Between Thornborough, Nosterfield, and East Tanfield, a complex of three late Neolithic/early Bronze Age, almost identical, Class IIa henge monuments (an embankment between two ditches) form a mile-long, approximate alignment roughly northwest to southeast. As part of the Thornborough Henges NMP project, the henges were surveyed at 1/2,500, and the features mapped. The henges are sub-circular enclosures, with two opposed entrances. Details of the infilled ditches are visible as cropmarks and/or shallow earthworks. Excavations identified phased construction, the outer ditches with an external bank were constructed first while the larger, more-impressive inner bank and ditch is a second phase. Excavation revealed white, gypsum-covered banks. Thornborough Centre's inner ditch measured 17.7 m wide and up to 2.1 m deep, similar to the dimensions of the North and South henges, and the up-to-18m-wide banks were deliberately leveled along the outer boundary. Cursuses, pit alignments, post moulds, and burial sites accompany the henges.

  • Thornborough North is situated in dense woods and remains best preserved.
  • Thornborough Centre has the highest embankment, reaching to near 5 m. The widest external diameter is 238 m. The inner ditch has squared terminals. The outer ditch is segmented and narrower. The two entrances, located to the northwest and southeast, are not perfectly aligned. The cursus is visible within the overlain earthwork. Aerial image.
  • Thornborough South is most damaged, by agriculture and bulldozing. A 350 m long double pit alignment was discovered near to and west of the henge. Aerial image.

Hutton Moor Henge, with an external diameter circa 240-254 m, represents one of the largest of henges, and the largest in the region. The 45 m wide embankment, with entrances at bearing 172 and 348°, is 173 m across, and remains to 3 m high. As at Thornborough, the ditch terminals were squared at the entrances. While quite reduced and denuded by agricultural tillage, the inner ditch, visible as a slight depression 5 m wide, was circa 10-18 metres wide with a 93-96 m internal diameter range. The wide external ditch was traced around the entire earthwork except at the entrances.

Nunwick Henge is situated on the axis of Thornborough North and Centre. Nunwick was located on aerial photographs and, while reduced and denuded by modern ploughing, remains visible as a cropmark with two opposed north and south entrances, bearings 129° and 350° from north. A shallow internal ditch and low bank remain with a slight, wide, traceable external depression up to 210 m in diameter. Excavation in 1961 by D. P. Dymond determined the bank was 18 m wide and the ditch was 14 m wide and 1.80 m deep with a 9 m wide berm between the bank and ditch.

Cana Barn Henge, much reduced and obliterated by cultivation, is visible as cropmarks. The earthwork has a ditch and outer bank up to 174 m wide with opposing entrances 40 m wide at 169 and 354° from north. Soilmarks on aerial photographs indicate internal features. Both the Hutton Moor and Cana Barn henges are located on a ridge.

File thornborough.xls has an additional scatterplot. Placemarks thornborough.kmz.

Tenlands Henge is about 58 m wide and survives as a cropmark near Cana Barn Henge.

Devil's Arrows Stone Row at Boroughbridge currently consists of three immense, standing stones, 6.9, 6.7, and 5.5 m tall and 5.5 to 6.7 m in circumference. Only one menhir in the British Isles is taller; 7.8 m Rudston Monolith is located due east, at 0.634 degrees arc distance. The Devil's Arrows form a 174 m long, approximately-straight line on an axis 26 degrees west of north. In 1538, Leland described a fourth center stone, with the center menhirs only six to eight feet apart. Alternate names include the Devil's Bolts, the Three Greyhounds, and the Three Sisters.

Castle Dykes Henge is a well-preserved oval bank to 82 m in diameter, over 1 m high and 9 m wide, with an internal ditch 10 m wide and 1 m deep. An eastern entrance faces the highest viewpoint. The earthwork is situated on a hill spur, about 30 km WNW of Thornborough.

Yarnbury Henge consists of a rock-cut ditch 3 m wide and 0.50 m deep, and an external bank of turf-covered stones up to 35 m in diameter, 0.50 m high and 4 m wide. Near the entrance (on the south-east) a 10 m section of the bank and ditch were destroyed by recent quarrying. The henge is situated on a slight rise, about 30 km SW of Thornborough.

Newton Kyme Henge is visible as cropmarks and survives as a slight earthwork. The henge, a sub-oval enclosure with three ditchs and a 1 m bank between the inner and middle ditches, has a maximum diameter near 250 m. The inner ditch has opposed entrances at 170 and 350 degrees, while the middle and outer ditches are irregular and segmented. Ground survey in 1979 reported a wide, oval inner ditch visible as a slight hollow and widely separated from the outer ditches (ditch diameters about 210, 180 and 90 m). The Class IIA henge has close parallels with the regional group of Late Neolithic/Early Bronze Age Yorkshire henges. Newton Kyme is south of Devil's Arrows over 20 km.

Ferrybridge Henge has the typical circular bank with concentric inner and outer ditches. Ferrybridge Henge overlays smaller circular monuments—hengi-form monuments and circles of possible post pits—dated between 3500- 3000 BCE. This southernmost of the Yorkshire henges is located about 58 km SSE of Thornborough Henges.

Catterick Henge was lost to quarrying. A pit cluster was closely associated with the henge. A 38 m wide cairn incorporated into the embankment may predate the henge monument.

Thornborough Cursus, visible as a cropmark, is overlain by the southern sections of Thornborough Centre and is visible between the ditch and bank. The rounded south-west end and most of the monument west of the henge was destroyed by gravel quarrying, during which a stone burial cist was discovered . Excavations were undertaken in the 1940s and 1950s. No north-eastern terminus was determined. The 44-55 m wide cursus runs roughly NE-SW for a known length near 1200 m. Fill from the up to 3 m wide by 1 m deep ditches was banked on the inner sides. OSGB Grid Reference SE 2808 7899 to SE 2884 7958.

Scorton Cursus destroyed by gravel quarrying.

Initial findings widened the area under study. Some of the more distant sites are not yet described here, such as Hastings Hill and West Agra. Site coordinates follow below.

2007.01.11 - Other projects and research keep distracting from this writing, so I'm posting terse results for now, in the Results and Observations table below.

2007.01.16 - The builders at Thornborough have taught me a lesson, forcing me to consider a new viewpoint on eclipses, the heliocentric perspective. Lunar orbit and lunar phases are geocentric, so, as the earth and moon orbit the sun, solar illumination rotates 360 degrees and there is one less full moon cycle than lunar orbit per solar orbit. Both heliocentric and geocentric motion ratios determine eclipse and lunar phase periods, and heliocentric geometry underlies the mathematics. The Thornborough results focused my attention on a specific arc module underlying eclipses and provoked questions about builder knowledge and archaeocosmology.

The Thornborough arc distances focused my attention on a module, termed S22 for convenience, defined as degrees solar orbit per lunar nodal period. To picture the S22 module, imagine the series of lunar nodal crossings from the solar perspective with the moon inscribing a wave pattern on the celestial backdrop, steadfastly passing the earth and being passed in turn while moving up and down, above and below the earth's plane of orbit, the "ecliptic." S22 is a tick of the eclipse clock, the length of the lunar nodal wave from heliocentric perspective, one of the two intervals determining eclipses. The arc distance is earth's somewhat steadfast orbital motion, the S22 module is defined by the mean arc per the moon recrossing the ecliptic. Knowing about eclipse timing is one thing. Knowing how many degrees of solar orbit motion a nodal period equates to is an entirely different, advanced order of understanding. Evidence of the module implies possible knowledge of the actual cosmology.

Previously, I introduced two equivalent astrogeodetic modules, S27 and S29, in an Astronomy and Astronomical Modules discussion. In quick summary, counting periods counts motion and I employ the motion quantities in analyses. Study results pointed out the S22 module (see results table below), due to the value's approxiation to the S27 module.

Does the S22 module at Thornborough evidence heliocentric knowledge? In ArchaeoGeodesy, I added an eclipse calculator to facilitate this exploration. It uses the vlookup feature; you type in the variable code from the adjoining list and the calculator uses the correct value automatically. During the Neolithic, in Universal Time (UT1) the modules had the following values:

Module Code
Distance/Time, Degrees of Orbit
Motion and Period
Solar orbit per lunar nodal period
Solar orbit per lunar orbit
Solar orbit per lunar synodic period

Selected Results and Observations

The site coordinates are shown below and integrated in archaeogeodesy.xls using the vlookup feature. You can input the site codes, such as "thorn" for Thornborough North, and the application employs the appropriate latitude and longitude. The calculator returns arc distance in degrees, km, miles, radii, circumference, and astrogeodetic modules. It also returns site-to-site bearings in degrees and displays illumination declinations for solstices and lunar extrema using a user-specified date. You can examine the cited relationships further using the application.

Results and Observations

Regarding the shorthand code, the terms and values key is in the archaeogeodesy.xls spreadsheet. The module noted at Thornborough is heliocentric and eclipse related, S22 or degrees of earth orbit per nodal month. S22 represents the frequency of the lunar nodal period. S22 is angular measure from heliocentric reference of the lunar nodal period on the ecliptic ( = 26.82059°).

thorn - thors = 0.00050 S22
thorn - thorc = 0.00025 S22
thors - thorc = 0.00025 S22
thorc - nunhe = 0.0020 S22
thorn - thorc - nunhe = 179.96°
thorc - nunhe - devar3 = 179.92°

thorc - hashi arc = 0.02501 S22
thorc - hashi N-S = 0.02499 S22 

humoh - rudmo = 0.02500 S22
humoh - hahib = 0.02498 S29 

Devils Arrows and Rudston Monolith
Two tallest menhirs in England
devar - rudmo = E-W line
devar - thorc = cir/2400

Silbury Hill and Marlborough Mound
Two largest mounds in Europe
silhi - marmo arc = cir/4800
silhi - marmo long E-W = cir/3000

2007.07.07 - Newark Circle, the largest earthen henge in the Americas, resembles the Thornborough henges. The arc distance from Thornborough South to Newark Circle equals 2.0 S22. The S22 spacing of the Thornborough henges repeats in the latitude and longitude differences between Newark Circle and Newark Octagon (nocp). The arc distance of the hypotenuse at Thornborough equals the latitude and longitude differences at Newark (0.0005 S22). From Thornborough South, the arc to Newark is 8,000 times the distance to the central henge.

Thornborough's lunar major alignment is noteworthy. From Thornborough South, the lunar major northerly set extrema aligns with the other henges. Assuming zero degrees apparent altitude, the center-to-center line from the south to the center henge matches lunar major during the epoch with 24 degee obliquity, about 2758 BCE. At an altitude of about 0.82 degrees, the north and south henges match the alignment. Between these two with altitude of zero, the lunar major alignment points to Ben Nevis, the highest point on the British Isles. Given these initial findings, the lunar extrema alignments may merit field study considering actual horizon altitudes and other monument alignments.

2008.03.12 - Newark and Thornborough present similar evidence inferring geodetic knowledge of their local latitude to longitude ratios. The Thornborough North and Thornborough South henges form a 3:4:5 triangle and their longitude difference in degrees equals their arc distance. The Octagon to Newark Circle N-S and E-W degree differences are equal, and these arcs are also equal to the Thornborough hypotenuse (data below). The Octagon azimuth nearly matches the local latitude:longitude angle, and one octagon side is an exact match. Reinforcing the inference on a large scale, Newark Earthworks and Marietta Earthworks, downstream at the Ohio River, are situated 1/365th the circumference of the earth apart. Their longitude difference is equal, also cir/365. (More discussion of Newark and Marietta archaeogeodesy and archaeoastronomy.)

2008.06.12 - Thornborough presents the same arc distance as that from Stonehenge to the West Cursus terminus. The arc distance from Stonehenge to the Cursus W terminus (0.01336° = 0.00050 S22) matches the thorn-thors spacing. More at:

Landscape Geometry of the 'Cursus' and Stonehenge

ArchaeoBlog, an archaeology web log by James Q. Jacobs

ArchaeoBlog - 2007.01.14

2007.01.14 - The Thornborough Page is updated with a study results summary. The results caused me to contemplate a new perspective on eclipses, a heliocentric model. In the results, an eclipse related module termed S22 is prominent. S22, my AeGeo programming term for solar orbit per lunar nodal period, equals 26.820613 degrees. We think of eclipses from a geocentric perspective for the obvious reason. However, eclipse frequency is a function of two motions, earth orbit of the sun and lunar orbit of the earth. The planes of these two orbital motions do not match, they incline 1/70th of a circle, sufficient to limit eclipses to when full moons and new moons coincide with the moon crossing the illumination plane of the earth. The lunar orbit nodes with the ecliptic are the points where the moon crosses the earth's orbit plane.

Full moons and new moons are a geocentric phenomena. Except during lunar eclipses, half of the moon is always lit by the sun. Lunar orbit around the earth determines when we see the illuminated half. Earth's heliocentric orbit factors in determining how often we have a full moon. If the earth were stationary, of course each lunar orbit would equal one full moon cycle. Instead, due to the earth and moon orbiting the sun, solar angle changes 360 degrees each solar orbit, or one less full moon than lunar orbits for each solar orbit. Heliocentric perspective is integral to eclipse timing, and a heliocentric cosmovision underlies the geometry and math. Knowing about eclipses and predicting their timing is one thing. Knowing how many degrees in solar orbit a nodal period equates to is an entirely different order of understanding. Regarding the Thornborough builders, I wonder, "How much did they know, and when did they know it?" And, "How precise was their knowledge?"

As I'm writing about Thornborough and thinking about the past (and future) at the henges, I'm wondering also if something important related to eclipses is going on with geometry of the larger regional complex. Maybe the import of the heliocentric perspective is all that escaped me. Eclipses are, after all, the astronomer's cosmic clock, important at least from our humble and fragile geocentric sphere. To ancient astronomers, all counts and measure may have hinged on these precise displays of cosmic geometry. For ancient geodesy, lunar eclipses may have enabled accurate longitude finding, while half the world briefly sees the same clock and each person sees the moon at a different location in relation to the celestial backdrop.

In prose, what is S22? Try to imagine from the solar perspective the frequency wave of lunar nodal crossings, the moon inscribes the wave on the celestial backdrop, passing the earth and being passed in turn, quickening and slowing while moving up and down above and below the earth's orbit path. S22 is a tick of the eclipse clock, the length of the moon's nodal wave from a heliocentric perspective as the moon orbits us. Enjoy the surfing.

Further Results and Observations

ncec - thors arc = 1.99999 S22 = 53.6410°
thorn - thors arc = 0.0005 S22 = 0.01347°
ncec - nocp   N-S = 0.0005 S22 = 0.01366°
ncec - nocp   E-W = 0.0005 S22 = 0.01319°

nocp - macam = 0.9863° = cir/364.995
nocp - macam E-W = 0.9864° = cir/364.963

Lunar orbit : Earth rotation = 0.03650 : 1.0

2012.08.06 - A few deep decimal changes were made to this page while reviewing results with updated astronomy formulas and with Universal Time conversions.

Thornborough Henges, the Ure-Swale, and Surrounding Neolithic Monuments




Coordinate Source


Hasting Hill Enclosure



English Heritage NMR


Hasting Hill Barrow


54.88353 1:2,000


Dora's Seat


54.69388 1:4,000


Devil's Stone


54.28770 1:1,000


Addlebrough Cairn


54.28873 1:1,000


Stony Raise Cairn


54.27792 1:1,000


Castle Dykes Henge



English Heritage NMR


West Agra




Catterick Henge



English Heritage NMR


Great Crakehall Barrow


54.29875 1:2,000


Cowling Lane Round Barrow


54.29255 1:2,000


Pickhill Moated Mound


54.24779 1:4,000


Three Hills Tumuli


54.21574 1:2,000


Thornborough North A



English Heritage NMR


Thornborough Cursus NE



English Heritage NMR


Thornborough Centre B



English Heritage NMR


Centre Hill Round Barrow


54.20692 1:2,000


Thornborough Cursus SW



English Heritage NMR


Thornborough South C



English Heritage NMR


Rush Wood Tumulus


54.20306 1:2,000


Hallikelds Tumuli


54.17648 1:2,000


Hallikelds Tumuli


54.17454 1:2,000


Hallikelds Tumuli


54.17347 1:2,000


Nunwick Henge



English Heritage NMR


Burtree Hill Tumulus


54.16362 1:2,000


Hutton Moor Henge



English Heritage NMR


Hutton Moor Tumulus


54.15625 1:2,000


Harlands Plantation Barrow


54.15334 1:2,000


Low Barn Tumulus


54.15127 1:2,000


Low Barn Tumuli


54.14946 1:2,000


Low Barn Tumuli


54.14839 1:2,000


Blois Hall Round Barrow


54.14632 1:2,000


Cana Tumulus


54.14301 1:1,000


Cana Barn Henge



English Heritage NMR


Tenlands Henge



English Heritage NMR


Devils Arrow N



English Heritage NMR


Devils Arrow C



English Heritage NMR


Devils Arrow S



English Heritage NMR


Yarnbury Henge


54.08464 1:1,000


Twelve Apostles


53.90160 1:2,000


Newton Kyme Henge



English Heritage NMR


Ferrybridge Henge


53.71248 1:5,000


51.44209 1:5,000
Silbury Hill
51.41571 1:5,000
Marlborough Mound
51.4166 1:2,000
Mont Blanc

Ben Nevis


56.79685 1:3,000


2007.12.22 -  Winter Solstice and Long Barrows  
Astronomy Constants and the Avebury Landscape?  Perhaps

Thornborough Area Monuments: thornborough.xls  |  thornborough.kmz

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© 2007 by James Q. Jacobs. All Rights Reserved.

Sources and Further Readings

  • AF Harding, with GE Lee 1987. Henge monuments and related sites of Great Britain: air photographic evidence and catalogue, BAR British series 175.
  • Aubrey Burl 1993. From Carnac to Callanish: the prehistoric stone rows and avenues of Britain, Ireland and Brittany Dymond, DP 1963. The "henge" monuments at Nunwick, near Ripon. 1961 excavation. The Yorkshire Archaeological Journal 41:88-107.
  • Harding, Jan The Neolithic Monument Complex of Thornborough, North Yorkshire Maps and index to site.
  • Harding, Jan and Ben Johnson The Mesolithic, Neolithic And Bronze Age Archaeology Of The Ure-Swale Catchment,  See also:
  • Henges NMR Monument Report, English Heritage March 9, 2006 (personal communication).
  • Ruggles, CLN and AWR Whittle 1981. Astronomy and Society in Britain during the Period 4000-1500 BC, BAR Series vol 88.
  • Thomas, N 1955. The Thornborough Circles, near Ripon, North Riding. The Yorkshire Archaeological Journal 38:425-45.
  • Vatcher, F. 1960. The Yorkshire Archaeological Journal 40:169-182.
  • Ladybridge Farm, North Yorkshire - The case against quarrying.
  • RESCUE's letter of objection to the extension of quarrying.



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