Origins of Stonehenge - A Season/Weather Forecaster

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A Season/Weather Forecaster

Contents -

(5) A Possible Primary Function of the Stonehenge Site

(6) Progression of the Sunrises

(7) A Clock of the Seasons

(8) ~ 8000 BC, Pine Post Holes

(9) ~ 3100 BC, Aubrey Holes

(10) ~ 2600 BC, Q and R Holes

(11) ~ 2400 BC, Sarsen Stones

(12) ~ 1600 BC, Y and Z Holes

Further Work

(13) Personal Thoughts

(14) Further Investigations and Other Ancient Stone Structures

Sources (bibliography)

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(5) A Possible Primary Function of the Stonehenge Site
( worship the Sun God and make sacrifices ! ?)

A very simple way to mark the passage of time is to observe the position of the sunrise, which moves across the horizon in an annual cycle. When the sunrise position stops and reverses direction then it is either midsummer or midwinter.

A number of sources on the Internet describe the Stonehenge site as a rural calendar, but I don't think that was it's primary function - rather a secondary function arising from the primary. I think the primary function was a rural clock - or season/weather forecaster - as in a measuring instrument that measures time not in hours or minutes but in the basic seasons of the year. Eventually this could have developed into a formalised calendar of the rural season, which may have numbered twelve.

Clock -

"An instrument other than a watch for measuring or indicating time, especially a mechanical or electronic device having a numbered dial and moving hands or a digital display"

Calendar -

"Any of various systems of reckoning time in which the beginning, length, and divisions of a year are defined"

I have discovered Joseph Norman Lockyer's Stonehenge Astronomically Considered, 1906, Chapter 3, Wikipedia's description, and a number of modern writers, who do give Stonehenge the functions of a clock, and calendar, among others.

The position of the Stonehenge site is interesting as the area around the intersection of the tributary to Stonehenge bottom (which appears to have been a river - now dry) to the East of the site was likely to have been marshy or at least liable to flooding. Hence this was likely to have been relatively clear of forest enabling the viewing of the horizon and the sunrises. It would also be accessible via the waterways and thus easy to find and travel to and from.

(6) Progression of the Sunrises

The sunrises on the earth's horizon moves towards the North for summer and the South for winter. Thus it moves backwards and forwards over an arc for one complete cycle and it's position and direction of movement indicates the time of the cycle.

For a dynamic illustration go to Sun's Position on Horizon

or copy and paste and search Sun's Position on Horizon (unl.edu)

Note, click on the yellow button at the bottom right hand side of the picture.

Please refer to Figure 6.1 - a static illustration.

Figure 6.1 Progression of the Sunrises

360° Compass Bearings

Any particular point on the earth’s horizon from a fixed observation point can be located by the standard trigonometric 360° clockwise circle with the North at 0°.

Thus the position of a sunrise can be noted as the number of degrees clockwise from grid North.

Please refer to the figure 6.2 below

Figure 6.2

There are three ‘norths’ commonly in use in Great Britain:

1 True North: the direction of a meridian of longitude which converges on the North Pole.

2 Magnetic North: the direction indicated by a magnetic compass. Magnetic North moves slowly with a variable rate and currently is west of True North in Great Britain.

3 Grid North: the direction of a grid line which is parallel to the central meridian on the National Ordinance Survey Grid. The difference between grid north and true north is very small and for most navigation purposes can almost always be ignored.

In the following diagrams, unless otherwise specified, the Grid North is used.

The sunrise point for a specific date has moved by approximately 1˚ since 2000 BC. That is 1˚ to the North for midsummer and 1˚ to the South for midwinter. For the purpose of this article this is considered to be negligible.

The sunrise point in the diagrams are defined by the first glimmer of the sun. However the sunrise can the defined as one of 3 positions - the first glimmer, half the sun visable, or the whole of the sun. As the difference between the 3 is only a few degrees it is consider negligible for a general analysis of stone structures. Other factors such as the displacement of stones over 4500 years cause a far higher error margin.

Intervals of the Sunrises Progression’s Arc

An arc of fixed markers, such as stones or pits, evenly spaced can be used to note the position of the sunrises and the expected weather. If the direction of the progression of the sunrises is noted the future weather, or season, can be predicted.

Unequal Intervals -

The movement of the sunrises progression across the horizon’s arc is not linear, but slows down towards the point of movement reversal (midsummer and midwinter) Thus for equal time periods of the annual cycle, as in weeks, the points for the periods will not be equally spaced. Please refer to Figure 6.3 below.

Figure 6.3 Equal Time Periods (i.e. weeks)

Note - the angles are approximate and used for the illustration of the point.

Equal Intervals -

So if the sunrises progression movement is divided into equal intervals, the annual cycle will not be divided into equal time periods. But the time of the cycle and the expected weather at that time will be constant over the continuous annual cycles.

Thus an arc of fixed markers at regular and equal intervals can be used as a practical calendar, and a season/weather forecaster.

Please refer to Figure 6.4 below.

Figure 6.4 Unequal Time Periods (evenly spaced fixed markers)

Comparison Between Equal and Unequal Intervals -

The difference between the equal and unequal (variable) interval division of the progression is not that significant., especially if the only interest is the prediction of the future seasons and weather. Please refer to Figure 6.5 below.

Figure 6.5 Comparison Between Equal and Unequal (Variable ) Intervals

(7) A Clock of the Seasons

By accurately marking the positions of midsummer and midwinter sunrises and dividing their interval into appropriate time intervals, a clock of the seasons can be made. As an apprenticed farmer of the early 1960s, it seems to me that these ancient people would have used four basic season intervals of spring, summer, autumn, and winter, as these are usually the most obvious from the weather and plant growth; usually - but not always.

These could be divided into early or late, or early, mid, and late. This gives three possible intervals of four, eight, or twelve. Six intervals over one movement of the sunrise progression would be a reasonable division, giving 12 over one forward and backward movement for a complete cycle - as in one year, and may explain our present system of twelve months to a year.

An arc of six or seven stones that covers the sunrises progression will give a 12 interval annual cycle based on natural agricultural seasons as in Figure 7.1 below.

hot, cold (summer, winter)

midsummer, midwinter (important for nomads)

spring, midsummer, autumn, midwinter (important for farming)

early/mid/late spring, early/mid/late summer, early/mid/late autumn, early/mid/late winter

(important to more efficient farming and an evolving settled social order)

Figure 7.1 Annual Cycle Seasons

Hence the fixed points of the structure are the display, and the rays of the sun are the hands of these 'clocks'.

(8) ~ 8000 BC, Pine Post Holes

These are - to date - the first known structures at the Stonehenge site. Although I could not see how these could be used as fixed reference points for the sunrises they could be used as a fixed observation point for known natural ground points - which would be a natural early development of a very simple season/weather forecaster.

I visited Stonehenge at dawn, midsummer, 2014, and personally observed from the pine post holes that the sun rose over the intersection of the horizons of two low hills. Refer to figures 8.2 to 8.5 below. Magnetic compass readings {that may have a high error margin) indicated the spring and autumn sunrises were marked by the brow of a distant hill. The midwinter sunrise was on the horizon of a low hill with no obvious natural marker but at the site of Stonehenge itself - a coincidence, or was a fixed marker first erected here leading eventually to the Stonehenge ?

Pine post holes: A ~ 8275 BC, B ~ 7036 BC, C undated, WA9580 ~ 7890 BC

Figure 8.1 Four Pine Post Holes

The size of the holes could be an indication that there was regular replacement as each time the post was dug out, and a new one rammed and packed in, the hole size would tend to increase. Eventually a new hole would have to be dug. This would explain the different dates of the holes, although the time intervals seem rather long. However it may be that other holes have yet to be found.

Some 16th century North west American native Indians - a stone age culture as per the Neolithic cultures - had posts as ‘totem’ poles that served non-practical ceremonial functions. It may be that originally they had a practical ‘clock’ function too, that enabled a simple prediction of future seasons and weather - useful to a hunter gatherer nomadic culture that followed a regular route following the food sources as well as vital to a settled farming culture.

Figure 8.2

24 June 2014, midsummer sunrise, observed from a pine post hole sight line.

Figure 8.3

24 June 2014, dawn. Intersection of two hills, observed from a pine post hole sight line.

Figure 8.4

29 December 2014, winter sunrise over the Sarsen stones, observed from a pine post hole sight line.

Although the date is seven days late from midwinter, the movement of the sunrise point is less than 0.5 degrees to the North - the movement is very slow at the ends of the sunrise progression. The old road embankment height has delayed the sunrise, causing a displacement to the South. Without this the sunrise would be close to the centre of the Sarsen stone structure.

Figure 8.5

29 December 2014, winter dawn.

Note the obstruction of the Sarsen stones of which only the tops are visible. This is caused by the built up embankment of the old road, now defunct. This sight line is slightly to the north of the pine post sight line to avoid the builders equipment.

(9) ~ 3100 BC, The Aubrey Holes

This consists of a circular earth bank and ditch with a circle of posts holes inside the bank. It is unclear as to how the Aubrey holes could be used as a season/weather forecaster since the full cycle of the sunrises progression covers 26 intervals or every two weeks, which is impractical for a farming purpose. This does show that it is not possible to make an accurate season/weather forecaster out of any ring of fixed points.

However it may not have been realized that the sunrises progression is regular and cyclic as any previous system using natural horizon features would be quite crude and of a coarse resolution - especially with the irregular observations due to cloud and morning mist cover.

The building of an entire ring would enable the observation of not only the sunrises but also the sunsets and the moon’s movements, which seem to have been important to humanity throughout human history. With this ring of fixed points the sages should of been able to observe and realize the regular cyclic movement of the sunrises and most importantly their association with the seasonal weather patterns - and hence the development of an annual clock and, perhaps, simple measurements of the movements of the planets and stars.

Refer to Figure 9.1 below.

Figure 9.1 The Aubrey Holes Orientation to the Sunrises

(10) ~ 2600 BC, Q and R Holes

Although often described as a double ring there is no evidence for this that I could find other than by an assumption from the arc. There is some evidence that it was not a double ring in the absence of holes as shown in Figures 10.1 and 10.2. In 'Stonehenge, Exploring the Greatest Stone Age Mystery' by Mike Parker Pearson 2012 (a good read and well worth buying) it is described as an arc. Any information on this would be very gratefully received by the author.

Please refer to Figures 10.1 and 10.2

Figure 10.1 Q and R Holes

Figure 10.2 Q and R Holes

It is very noticeable that the arc shows a particular interest in the sunrises progression and being built of stone forms a more permanent and stable structure.

Figure 10.3. Q and R Holes Orientation

(11) ~ 2500 BC, Sarsen Stones

The Sarsen stones forming the outer ring are so huge and complex it seems inconceivable that they were built only as a season/weather forecaster, important as that function would be. However the fact remains that they can be used as such and with surprising accuracy. It could be that they replaced a far simpler smaller structure of an arc design with the large holes for the Sarsens obliterating the smaller ones - leaving no trace.

Please refer to Figure 11.1

Figure 11.1 Outer Sarsen Stone Orientation in Seasons

It would be possible to develop the concept of an annual calendar from this structure, although obviously the names of the intervals would not be as today’s !

Please refer to Figure 11.2 below.

Figure 11.2 Outer Sarsen Stone Orientation in Months

The inner horse shoe shape of even larger, massive stones actually block the view of the late and early winter season sunrises although it is still possible to use the structure as a season/weather forecaster. But it is clear that this structure was far more than this. The stones are truly awe inspiring.

Figure 11.3 Outer and Inner Sarsen Stones Orientation in Seasons

(12) ~ 1600 BC, Y and Z Holes

At present the references books do not believe that anything was erected in these holes as excavations have not found any evidence for wooden or stone inserts. So they seem to have been just holes.

The centre of radius of holes Y1 to Y7 and Z1 to Z7 indicates an awareness of the point necessary for the observation of the progressions of the sunrises. This point gives a six interval progression for a twelve interval annual cycle. Thus this centre of radius seems to be of some importance.

However if the holes had continued on this radius they would have coincided with the outer Sarsen stones, but the remaining holes are centred on the Sarsen ring centre hence giving a double arc structure symmetrical to the Sarsen stones. This does not coincide with the holes (Y1 to Y7 and Z1 to Z7) that are centred on the observation point.

Please refer to Figure 12.1

Figure 12.1 Y and Z Holes Orientation

It is interesting to note that hole Y8 is located such that it lines up with the notched Sarsen S58 for the midwinter sunrise, although this could be a coincidence.

For further information on this refer to -

community.novacaster.com/showarticle.pl?id=11160

The midwinter sunset is already marked by the Sarsen stone’s orientation towards the midsummer sunrise, but the two observation times increases the chances of seeing the midwinter time through the winter clouds. The observation through the narrow gap between the inner Sarsens S51 and S52 is difficult and easy to miss.

Note, the date for the Y and Z holes is given as approximate, as dates are assumed from the presences of organic material. So an earlier smaller hole structure regularly dug out to remove debris from the winter storms would be completely lost - and the Y and Z holes could date back far further than has been assumed and could predate the stone structures. i.e. 4000 BC. This would explain their irregular and poor standard of build compared to the stones. For the dating of the holes please see Dating of Y&Z Holes

Thus they may have been as shown in Figure 12.2 below.

Figure 12.2 Y and Z Holes Orientation in Seasons

It is possible that there was an earlier hole structure consisting of the arc from Z1 and Y1 to Z7 and Y7, with the circle being completed at a later date, but with a misplaced center of radius. This center then formed the center of the later stone structures. The arc does seem to have been built with better regularity than the remaining circle.

Please refer to Figure 12.3 below.

Figure 12.3 Y and Z Holes Orientation in Months

The holes could be used to locate a movable marker as the sunrises progress and act as a visible season/weather forecaster for the community. As the marker's position would signify the direction of the progression there would not be any confusion between the seasons due to the irregularity of the weather.

Hence the Y and Z holes may have been a development from a simple monitoring of the changes of the seasons to an established twelve interval agricultural season calendar, with a marker to clearly indicate the position in the annual cycle. In the above diagram each interval has been given a modern name of a month to illustrate the point although the time of the month is not accurate due to the equal spacing of the fixed points.

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Thus the Neolithic nomad, equipped with the knowledge of a constant regular annual cycle of seasons and the means of predicting them, could establish successful and reliable farming leading to a settle community with an expanding population and technology...

And so with the first flush of sunrise came the first flush of settled civilization.

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Further Work

(13) Personal Thoughts

(the germination of agricultural science)

I have not considered the political, cultural, religious, ceremonial, etc. functions at all and leave this to far more knowledgeable historians and archaeologists. Nor have I considered the centre of learning and knowledge and University aspects, but have only considered a possible originating practical agricultural functionality with respect to obtaining a reasonable prediction of the weather through measurements and an understanding of the cyclic seasons on an annual basis.

But the final purpose of the Sarsen stone and Blue stone structures (Stonehenge) remain today a mystery that may never be solved, according to leading archaeologists and historians, and at present the stones stand silently awaiting an Archimedes revelation - eureka !

(14) Further investigations and Other Ancient Stone Structures

Evidence for a settled agricultural Neolithic tribe would be a season/weather forecaster, a livestock pen/corral enclosure and market place, and a hill fort. In addition there should be a field system and habitats indicating a population of at least hundreds - but time, weather, and human developments may have removed these.

A season/weather forecaster to enable successful cropping and livestock management, and reliable agriculture on a long term basis, a vital first for a settled culture.

A livestock pen/corral enclosure and market place to provide a safe place for livestock and crops in winter and to trade in summer.

A hill fort for a warrior group (gang !) to organise, manage, and protect (?) the tribe; as in recorded historical accounts of knights and castles.

According to Internet sources there are around 900 ancient stone structures in Britain although it is thought that originally twice that number existed, and thousands on a world wide basis. As I am now retired and free, I shall spend my remaining few years in checking the orientation of as many as possible to see if, as an East facing arc, they could be used as a season/weather forecaster, and irrefutable proof via an arc of six or seven fixed markers with a marked observation point that follow the sunrises progression in an area that shows populous Neolithic inhabitation and field systems.

Please refer to "Neolithic Structures - UK" ( Neolithic Structures - UK ) for the analysis of other British ancient stone structures.

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Neolithic Sunrise Calenders - UK (Evidence of Sunrise Orientation)

Appendix A - Calculations for Sunrises Angles

Appendix B - 'Stonehenge and Other British Stone Monuments Astronomically Considered'

Chapter 3, by Norman Lockyer, 1906

Appendix C - Dating the Y and Z Holes

Sources (bibliography)

Stonehenge, Exploring the Greatest Stone Age Mystery
Mike Parker Pearson 2012

Stonehenge, The Story So Far
Julian Richards 2007

Stonehenge, The Biography of a Landscape
Timothy Darvill 2006

Henge Monuments of the British Isles
Jan Harding 2003

Archaeology and Environment
Michael J Allen

The above books are interesting, beautifully illustrated, and well worth buying.

Stonehenge, in its landscape
R M J Cleal, K E Walker, and R Montague 1995

Britain's Prehistoric Achievements
Alan H. Grundy 1985

'Stonehenge and Other British Stone Monuments Astronomically Considered' Chapter 3,
Joseph Norman Lockyer 1906

The above books are rather heavy but a must for a serious in-depth study of the archaeology of the site.

Photographs - Google Images

Diagrams - Wikipedia and author's own work

Please make any comments to - degray1982@gmail.com

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