The positions of the posts were recorded in a survey drawn up by Lt-Col Robert Cunnington of the Royal Engineers and according to his plans, the position of the first G-post was north.
If Lt-Col Cunnington did not take magnetic declination into account when drawing the plans, then all positions of the posts and stones should be rotated by 13 degrees so that the burial is actually facing east, rather than NE at approximately 80 degrees.
His plans are correct about the relationship of the posts and stones to each other, but possibly incorrect by 13 degrees with respect to True North.
If you use the plans as published, the G1 post is aligned north and it is possible to work out the positions of the other posts from their shadows at midsummer sun-rise and sun-set.
Imagine you were going to make a structure that embodied the directions of solstice (midsummer and midwinter) sun-rise and sun-set.
Raise the central post.
And then you use it to find North.
The Sanctuary was once five, concentric rings.
Constructed from timber posts. Latter, standing stones were added, and a further ring made entirely of stone encircled the monument. The addition of stone may have been contemporary with the closing off of West Kennet long barrow and the creation of a ceremonial way, to Avebury.
Today I want to consider one theory as to how the central wooden posts were given their positions.
The G ring is the central ring of The Sanctuary.
It consisted of six, fairly substantial posts. This ring was once considered to be the first ring because it contained the oldest pottery: 'Windmill Hill' and 'Ebbsfleet' (source English Heritage book on Avebury).
Ebbsfleet pottery is known as early Peterborough ware, so the time period is probably middle Neolithic approximately 3000 BC.
The G post holes were numbered from 1 to 6.
They were substantial post holes, big enough to each hold an oak post, one foot in diameter.
The G post holes are indicated on the ground at The Sanctuary by red-topped, concrete posts, but unfortunately these are no longer accurately positioned.
To get some idea of what they may have been like....
From M E Cunnington's notes.
Central post hole.
The central post hole was small, more like an F post.
On this plan (from ME Cunnington's excavation- link) the G holes are marked in green, and have been placed over a grid to give some idea of their relationship to each other.
In Lt-Col Cunnington's plan, the posts: G4. central post and G1 create a north-south line.
Why find North?
Because it is the place sun and moon never go.
That's kind of weird...
Because you wouldn't bother digging deep holes and hauling great weights of tree around unless there was something clever going on.
So, first task is to find North from the central post
The first post, North post G 1 (the green blob in the picture) is raised.
What time of year is this?
Midsummer.
You have almost a month to complete this task because the sun rise and set positions remain fairly constant for that long! I used to think it was something like three days...but nope, more like a month.
At midsummer, the sun rises behind the barrows at an azimuth of something like 50 degrees, but by the time it climbs the hill the azimuth has increased.
To what I couldn't tell you.
I filmed it at the time...
Not a long journey from the West Midlands down to Wessex chasing the full moon.
But it was so cold there!
I laid out the string to show the paths...
Finding my compass was out of the question.
Felt I was risking frost-bite when I took off my glove!
But what struck me was that it didn't work.
The sun didn't line up with the paths.
If Lt-Col Cunnington's plans are right it never worked...
If Lt-Col Cunnington's plans are wrong...the sun would have lined up with the paths...I shall probably never know!
But let's continue with the Lt-Colonels plan- if the plans are correct then the G posts could have been positioned using the longest shadows at the summer solstice.
Using the shadow from the North post, G 1 at sunrise
The position for post G6 is found.
As the diagram shows, the rising and setting sun could cast a shadow in the correct position.
Using the shadow from the center post, the position for the next two G posts is found.
The final post to be raised is G4, at the South.
These three posts are empowered with offerings.
Thereafter at every sunrise during mid-summer, for as long as the posts endure, the South East or the North-West is closed off when the shadows line up with the other posts.
And as the sun sinks, the shadows once more line up to close off significant directions.
The wooden posts, even though thick and heavy would decay and need to be replaced, and this I'm guessing would lead to the structure changing, evolving into something more complex.
Facing East. |
It consisted of six, fairly substantial posts. This ring was once considered to be the first ring because it contained the oldest pottery: 'Windmill Hill' and 'Ebbsfleet' (source English Heritage book on Avebury).
Ebbsfleet pottery is known as early Peterborough ware, so the time period is probably middle Neolithic approximately 3000 BC.
The G post holes were numbered from 1 to 6.
They were substantial post holes, big enough to each hold an oak post, one foot in diameter.
G ring . |
The G post holes are indicated on the ground at The Sanctuary by red-topped, concrete posts, but unfortunately these are no longer accurately positioned.
To get some idea of what they may have been like....
From M E Cunnington's notes.
- The G posts were numbered from 1 at the north, clockwise to 6.
- The posts were in a circle, 6 foot from the central post
- The average measurements of the post-holes- 24" 61 cm diam (bottom) x 60" 152.4 cm deep.
- G1-
- G2- Fragment red deer antler at bottom.
- G3- Pottery shards. "One ornamented with rows of deep grooves resembled the Woodhenge type".
- G4- Fragment red deer antler at bottom.
- G5-
- G6-
The central post hole was small, more like an F post.
- The base diameter of the hole was 10 inches/ 25.4 centimetres.
- The depth of the hole was quite deep, 3 foot, six inches-106.7 cm
- The post hole contained a few flakes of flint, some sarcen stone, some animal bone fragments and evidence of fire at some point, charcoal.
On this plan (from ME Cunnington's excavation- link) the G holes are marked in green, and have been placed over a grid to give some idea of their relationship to each other.
In Lt-Col Cunnington's plan, the posts: G4. central post and G1 create a north-south line.
Why find North?
Because it is the place sun and moon never go.
That's kind of weird...
Because you wouldn't bother digging deep holes and hauling great weights of tree around unless there was something clever going on.
So, first task is to find North from the central post
The first post, North post G 1 (the green blob in the picture) is raised.
What time of year is this?
Midsummer.
You have almost a month to complete this task because the sun rise and set positions remain fairly constant for that long! I used to think it was something like three days...but nope, more like a month.
At midsummer, the sun rises behind the barrows at an azimuth of something like 50 degrees, but by the time it climbs the hill the azimuth has increased.
To what I couldn't tell you.
I filmed it at the time...
Not a long journey from the West Midlands down to Wessex chasing the full moon.
But it was so cold there!
I laid out the string to show the paths...
Finding my compass was out of the question.
Felt I was risking frost-bite when I took off my glove!
But what struck me was that it didn't work.
The sun didn't line up with the paths.
If Lt-Col Cunnington's plans are right it never worked...
If Lt-Col Cunnington's plans are wrong...the sun would have lined up with the paths...I shall probably never know!
But let's continue with the Lt-Colonels plan- if the plans are correct then the G posts could have been positioned using the longest shadows at the summer solstice.
Using the shadow from the North post, G 1 at sunrise
The position for post G6 is found.
As the diagram shows, the rising and setting sun could cast a shadow in the correct position.
Angle and length of shadows at midsummer superimposed over G post holes, 1, 2 and 6. |
The final post to be raised is G4, at the South.
These three posts are empowered with offerings.
Thereafter at every sunrise during mid-summer, for as long as the posts endure, the South East or the North-West is closed off when the shadows line up with the other posts.
And as the sun sinks, the shadows once more line up to close off significant directions.
The wooden posts, even though thick and heavy would decay and need to be replaced, and this I'm guessing would lead to the structure changing, evolving into something more complex.
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