I recently came across Rock Art and Ritual by Brian Smith and Alan Walker, (subtitled Interpreting the Prehistoric landscapes of the North York Moors. Stroud: History Press 2008. 38.). It tells the story: Following a wildfire,  thought ecologically devastating, of many square miles of the North Yorkshire Moors, those interested in its few decorated stones headed out to see how these antiquities had fared.


Fire had revealed many more stones carrying rock art or in organised groups. An urgent archaeological effort would be required before the inevitable regrowth of vegetation.

BrowMoor decorated 1 Negative

Figure 1 Neolithic stone from Fylingdales Moor | Credit: Graham Lee, North York Moors National Park Authority. From <this site>

A photo of one stone in particular attracted my attention, at a site called Stoupe Brow (a.k.a. Brow Moor) near Fylingdales, North Yorkshire. The archaeology has been written up (in Proceedings of the Prehistoric Society. Volume 77. London: 2011. A New Context for Rock Art: a Late Neolithic and Early Bronze Age Ritual Monument at Stoupe Brow, Fylingdales, North Yorkshire. Vyner, Blaise.) The Prehistoric Society has a website detailing its publications including their proceedings, events, grants and membership. There is an online description of Stoupe Brow at ERA: England's Rock Art. 

Stoupe Brow.8

According to Blaise Vyner, this stone was originally upright, 90 degrees clockwise from its present position, and there is some weathering on its left side which perhaps led to this assertion. If so, this decorated stone is similar to those at Gavrinis (Carnac, Brittany) in that (a) it's engraved art is of a similar style and (b) had signs of having been outdoors at different locations/orientations prior to being incorporated in some sort of assemblage. At Gavrinis, engraved stones had been reused  to build a chambered tomb  whilst at Stoupe Brow. Parts of a probably egg-shaped stone circle was made using reused engraved and plain stones, surviving as a partial kerb integrated with at least one standing stone.


I have re-erected the stone photo according to Vyner and done some counting of elements so as to interpret the monument, not according to a possible anthropological ritual meaning, but from the standpoint of astronomy as practiced by the megalith builders.

BrowMoor C

Figure 3 (#10 of Vyner 2011) rotated into its likely original presentation, in negative and with extended calibration.


There are three main panels and two other related regions:

  1. A top panel made up of lozenges which in reverse are triangles whose bases touch the panel border. There are six such triangles on the bottom, then also touching the left and right panels.
  2. The left panel is a two by three rectangle, crossed by diagonals. The above triangle is scored by twelve vertical lines whilst the below triangle is scored by thirteen vertical lines. The left triangle is filled by a single chevron whilst the right triangle filled by a double chevron.
  3. The right panel has chevrons arranged loosely into a fish scale pattern containing twelve scales, leaving a thirteenth region of the panel empty.
  4. Between the left and right panel and below the top panel there is a strip terminated above but not below (hence not a panel), containing four whole lozenges, each with central dots.  Alternatively, there are triangles running along the sides of the left and right panels. Between the fourth and fifth triangles of the top panel is a vertical line central to these vertical lozenges, perhaps indicating connection between the two rows of horizontal and vertical lozenges.
  5. The top panel also plays host on three of its sides to what appear to be thirty seven small holes/dots, terminating in the right panel.

These panels appear now to belong to an area of fine sandstone about one lunar month (of 29.53 day-inch counting, 75cm) wide and one megalithic yard high, in (native) megalithic units, if the 30 cm measuring rod in the photo is expanded to metre rods and applied to the photo.


One can see some kind of play between numbers twelve and thirteen within both the left and right hand panels, and the dots and repeated geometrical elements suggest a relationship to the counting of days and aggregation of such counts into larger units. These are significant astronomical numbers in units of lunar months, since twelve and thirteen months bracket the solar year. These two lunar year lengths are sometimes alternated to fit the Metonic cycle of 19 years equalling 235 lunar months. Wikipedia says:

The solar year does not have a whole number of lunar months (it is about 12.37 lunations), so a lunisolar calendar must have a variable number of months in a year. Regular years have 12 months, but embolismic years insert a 13th "intercalary" or "embolismic" month every second or third year (see blue moon). Whether to insert an intercalary month in a given year may be determined using regular cycles such as the 19-year Metonic cycle (Hebrew calendar and in the determination of Easter)…  <https://en.wikipedia.org/wiki/Intercalation_(timekeeping)>

If two years of 12 months are added to one of 13 months then the total "three year" period is 37 lunar months long, and this corresponds to the number of holes running around the top panel and into the right hand panel.

  1. The left hand panels usage of 12 and 13 scored lines is accompanied by two triangles containing chevrons, two on the right and one on the left, and this could have presented the formula of adding two twelve month lunar years to one thirteen month lunar year.
  2. The right hand panel contains thirteen areas, the twelve "fish scales" and a thirteenth "left over" area, and this could represent the twelve lunar months between the end of the Saros eclipse period of 223 months and of the Metonic 19-year period of 235 months, if counted from an eclipse. (Whilst the Saros is the strongest eclipse period known for similar eclipses to occur, the Metonic is also an eclipse cycle including just over 20 eclipse years to the Saros exact 19 eclipse years.)

These thoughts suggest an interpretation of the top panel, which links the left and right panels in an endeavour to count these two 18 and 19 year cycles and present how this is done on a flat-faced orthostat or standing stone, exactly as was done in the Carnac area with similar graphical elements. In this sense the attempt here, to interpret Stoupe Brow decorated stone 1, is to identify it as a teaching text for astronomical cycles, originally upright but then incorporated within a semi-circular kerb, on its side perhaps to store or conserve it.

The six triangular shapes within the top panel suggest that each triangle was an aggregate of 37 lunar months so that six of these equalled 222 lunar months, just one month short of the 223 whole months within the Saros period. In previous posts I have noted, at Carnac, engraved stones graphically presenting the counting of units of 37 lunar months in order to approach the Saros to within one lunar month. (We must remember that counting lunar months is especially appropriate since eclipses only occur at new and full moon).

BrowMoor B 2

Figure 4 Interpretation of Stoupe Brow Decorated Stone 1 as a counting left to right of periods 37 lunar months long, to arrive within one month of an exactly similar eclipse to one just occurred.

It appears likely that the Phaistos disk found on Crete, and due the Minoan civilization, counted 222 lunar months, but then using the 364-day year of the Mediterranean prior to the Late Bronze Age Collapse in 1200 BC, for reasons also visible on this decorated stone in the line between triangles four and five, which appear to "give rise to" the vertical column of lozenges/triangles. If we divide 37 lunar months of 29.53 days = by the lunar orbit of 27.32166 days the result is 39.99 lunar orbits within 37 lunar months. It is therefore the case that each unit of 37 months can equally be viewed as 40 orbits, and I believe that (by explanation at the time) it was useful to build in four vertical units that would equal the four horizontal time periods. But these are shown as smaller to bring out the fact that the lunar orbital period is smaller than the lunar month. In the Phaistos article I came to realise that the 12.368 lunar months of our solar year of 365.2422 days (being the earth's orbital period), was usefully shortened to the twelve and one third lunar months within the 364-day year so as to count three such years to give the 37 whole lunar month aggregate unit.

This 364 day year was called the Saturnian year and it had other calendrical benefits such as 13 months of 28 days (4 times 7) and exactly 52 seven day weeks, the Saturn synod having 54 seven day weeks. But here, the idea of mixing twelve and thirteen month units prefigures that scheme, perhaps without a 364-day week. However, in terms of the 364-day aggregate unit, four times 37 months equals 148 lunar months, 160 lunar orbits and twelve 364-day years. The interpretations above can now be viewed graphically:


This stone probably reveals to us that 37 lunar months was known to equate to 40 lunar orbits, so that the Moon's month of phases is 40/37 of its orbital period; and finding such new relationships through the rock art increases the likelihood that the stone's subject was astronomical.

  1. It is numerically obvious that the 223 lunar month period of the Saros is exactly one month longer than six periods of 37 months (or 40 orbits), thus being a perfectly normalized triangle, normalized by the lunar month. N = 222.
  2. The Saros and Metonic are also perfectly normalised by the twelve months between those two periods, that is they are normalized by the lunar year. N = 18.583, slightly less than 18.618 since the 223 to 235 relationship is not exact.
  3. Added to this the Eclipse and Solar year are normalised by the time taken for the lunar nodes to travel on DAY in angle, that is they are normalized by 18.618 days. N=18.617.
  4. The differential length of three solar years and three lunar years gave the megalithic their "yard" of 32.625 day-inches, a unit by which both periods were normalized by 32.625 days. N = 32.585, the length of the astronomical megalithic yard in inches.


This stone, decorated without having a unified mathematical culture exactly like ours, had knowledge that solar-lunar periods (counted in day-inches) tended towards being unified through their differential lengths, such as the megalithic yard. If so, their astronomy could predict eclipses and other cyclic events without modern calculation or observation of exact celestial positions within a system of coordinates. Instead, observable events could be "counted on" to arrive at future events.