Stone 11 Shadow Effect

Stone 11 is the mysteriously half-height, half-width upright in the southern quadrant of the outer sarsen circle at Stonehenge.

Plan of Stonehenge indicating position of Stone 11

Stone 11 seen from the south

Several suggestions have been made to explain its curious dimensions - that the builders ran out of bigger stones, that it's a reused lintel, that it marks a division of the 30 uprights into three groups of 10 (the other marker being Stone 21) for calendrical reasons...

The 2012 Antiquity paper "Stonehenge Remodelled" (Darvill, T. et al. (2012) ‘Stonehenge remodelled’, Antiquity, 86(334), pp. 1021–1040. doi:10.1017/S0003598X00048225) offers:

...stone 11 (south) is narrower and shorter than the others perhaps to somehow mark the southern entrance (or it may even have been a later replacement).

None of those explanations have ever felt entirely satisfactory to me.

Recently I was watching Dr. Terence Meaden's video presentation to the 2024 Megalithomania Conference, on the topic of Pytheas the Greek's voyage to Britain and Thule.

Terence is always interesting and has had enlightening things to say about megalithic structures for decades. It was he that pointed out, for instance, that the Heelstone casts a shadow that penetrates into the centre of Stonehenge on the Summer Solstice (see "The Shadow of the Heelstone" on this site for more info).

While he was explaining his hypothesis that Stone 11 is of reduced height to represent "half" in the count of sarsens in the outer circle - ie that the circle conceptually held 29.5 stones rather than 30, and so could be used as a lunar calendar count, twelve times round it making 354 days then continuing the count on to Stone 11 would bring the day tally up to 365 and hence one solar year - he put up this diagram from his 2017 paper "Stonehenge and Avebury: Megalithic shadow casting at the solstices at sunrise":

Fig. 7 from "Stonehenge and Avebury: Megalithic shadow casting at the solstices at sunrise"
Journal of Lithic Studies (2017) vol. 4, nr. 4, p. 39-66 doi:10.2218/jls.v4i4.1920

Terence points out that the shadow of Stone 11 falls on Stone 40 at Winter Solstice Sunrise, and suggests that the male Stone 11 deliberately interacts with the female Stone 40 in this way.

Those familiar with his work will recognise this as a common theme in his research - phallic upright stones casting shadows onto recumbent receiving stones at key times in the year.

The next image in his presentation gave me goosebumps.

Stone 11 just after sunrise near Winter Solstice with the Sun at its rising azimuth of 2500 BCE

The shadow of Stone 11 can clearly be seen clipping the fallen Stone 14's right hand end (its upper end when erect), and Stone 40 (a bluestone) is directly behind this fallen sarsen lying prone in the turf - not visible in this shot, exactly under Stone 11's shadow. But that's not what grabbed me.

The shadow of Stone 11 continues across the ground and directly intersects with Station Stone 93! This contrast-enhanced closeup of Terence's image shows it well.

Stone 11's shadow hitting Station Stone 93

For this to happen, Stone 11 has to be a very particular height and width - any wider and its shadow will not match the width of Station Stone 93, any taller and the shadow will extend well beyond 93's peak.

We have to remember to account for the shift in the Earth's axial tilt from 24° to 23.5° since 2500 BCE. 

At winter solstice 2500 BCE, the Sun reached "full orb" over Coneybury Hill at an azimuth of 130° 20':

Full orb winter solstice Sun position, 2500 BCE

In our era, on the 27th December 2014 (when Terence's photo was taken), the Sun is at a higher altitude when it reaches this azimuth:

Sun's position on 27th December 2014 when it reaches azimuth 130° 20'

Its altitude in our era is 1° 6', back in 2500 BCE it was 0° 26' - a difference of 40' of arc. This difference puts the tip of Stone 11's shadow fractionally lower on Stone 93 now than it would have been then.

It seems likely that Station Stone 93 would have been completely and exactly engulfed by the shadow of Stone 11 cast by the full orb risen Sun at winter solstice in 2500 BCE.

Drawing this shadow line on the reference plan of Stonehenge from "Stonehenge in its Landscape" (Cleal et al, 1995), along with the secondary solstice axis identified originally by Gordon Freeman (see "The Secondary Solstice Axis" on this site) highlights their parallel nature.

Stone 11 shadow (black line) and the secondary solstice alignment (red line)

Zooming in on this, and incorporating the plan of the parchmarks for the missing stones 17, 18, 19 and 20 from "Parchmarks at Stonehenge, July 2013" (Banton, S., Bowden, M., Daw, T., Grady, D., & Soutar, S. (2014) Antiquity, 88(341), 733-739 https://doi.org/10.1017/S0003598X00050651) reveals an elegant aspect to this shadow line.

Closeup incorporating the plan of the parchmarks identifying the positions of Stones 17, 18, 19 and 20

... the shadow of Stone 11 (the black line) passes exactly through the gap where missing stone 18 and 19 would have stood (if indeed, they'd ever been erected - the jury's out on that one) - so it would not have been blocked by them.

In the end what does this mean?

It appears possible that Stone 11 was positioned and shaped to create a shadowplay effect at winter solstice when Stonehenge was built, one that targeted Station Stone 93 very precisely both in position and size.

If Stone 11 was fatter and taller, this wouldn't have worked so neatly.

All that remains to be explained is the leaning nature of Stone 11, because it is not perfectly upright.

Stone 11 leaning towards the south

... how does this affect things? Is it intentional? I'm looking at this picture and noticing that the right hand edge of the stone is almost perfectly vertical, compensating for the lean.

The investigation into that is a story for another day.

Many thanks to Terence for giving me permission to use his images.