1.   A Tentative Suggestion That The Carvings Were Initially Inspired by Faces In The Clouds

In my Photographer's Statement I summarize the work of enlightened scholars by stating that "Avebury is a delightful paradox, a temple intended to honour the spirits and the natural order by creating static art works that "move" as the light around them changed."   The art was unusual, mainly invisible except to initiated members of the community who knew when to search for carved faces at specific times of the day and year when the light arrived at the right angle to reveal the sacred characters/faces.   The rough monoliths guarded their secret sculptures showing only apparently blank masses of stone most of the time, then the faces emerged briefly in the appropriate light to often startling effect, only to then vanish again, submerged into the inherent "noise" of the natural sarsen background.   I ask myself what could possible have suggested such an astonishing mechanism to the neolithic farmers of Avebury?

The answer lies in animism and pareidolia.   The neolithic people regarded nature and reality as being driven by innumerable spirits who lived in every part of their world (animism).   Every plant, animal, rock, stream, ocean, breeze, storm, rainstorm were occupied by spirits.   Most of the time these spirits hid their true nature (for example when you looked at water you wouldn't actually see the water spirit who underwrote that water's reality, you just saw the water), the existence of the spirits was therefore usually only deduced by the ancients, but in the clouds their bodies and faces could sometimes appear to be directly discernable.

I am sure that most modern people have also had the experience of lying down outside on a sunny day, and watching faces, figures and characters emerge from the inchoate clouds above - a totally subjective experience known as pareidolia (according to Wikipedia "Pareidolia is a psychological phenomenon in which the mind responds to a stimulus, usually an image or a sound, by perceiving a familiar pattern where none exists. Common examples are perceived images of animals, faces, or objects in cloud formations").   This process has driven art in our own time too, can you remember the classic scene in the film "The Agony And The Ecstasy" where Michaelangelo is inspired by seeing clouds in the sky trace out the iconic sky figures of God creating Man? - sacred pareidolia!

My belief is that to the neolithic mind the sky faces created by pareidolia "proved" the animistic nature of the world, and the temporary existence of these faces in the sky inspired the distinctively mobile and transient nature of many of the Avebury sculptures/carvings.

I suggest that in neolithic Wiltshire worshippers noticed that raw clouds sometimes reconfigured into apparently meaningful religions shapes<+>, magically portraying the animistic nature of the neolithic world, and then watched awestruck as nature slowly erased the apparent sky sculptures, leaving only the background noise of featureless clouds.   This apparent cycle of sacred revelation and subsequent erasure and concealment was then built into the religious sculptures of Avebury in order to honour the animistic spirits seen in the skies.

My thesis here is supported by the existence at Avebury of so many "zenith-seeking" sculptures that look straight up overhead, a zone of the Wiltshire skies that never hosts the sun or moon. Accordingly I believe these statues might be looking for faces in the clouds above.

Furthermove I can imagine that when neolithic people found drifts of unshaped white/grey sarsen stones lying in the forests and grasslands around the Avebury landscape, they may have mistaken these for clouds fallen from the sky.  The ancient people might then have felt it appropriate and pious to transport these "sky stones" to the holy precincts of Avebury henge itself to carve them there with celestial faces.   Speculation on my part I know.

In short - Here I have turned the usual pareidolia argument on its head.   Usually pareidolia is cited as a Rorschach explanation for falsely seen images in the stones, I say instead that pareidolia encouraged the neolithic people to see transient faces in the clouds, and then replicate the emotional and visual impact of these celestial characters in their actual/real stone carvings.

Footnote:

<+> Around the time that Avebury was finally coming to the end of its prehistoric life, (abandoned in favour of Stonehenge), in far away Babylon Hammurabi's famous laws were being inscribed on a four-ton slab of diorite stone. Strikingly the prologue to the laws refer to Anunnaki and Igigi, respectively (1) evil spirits visible in the black clouds of the heavens, and (2) kind spirits visible in the white clouds (per W W Davies, p17 in his book "The Codes of Hammurabi and Moses", Cosmo Classics, New York 2010, from Davies' original 1905 text). This imagery is strikingly akin to the kind of cloud animism I am suggesting was observed and worshipped at neolithic Avebury.

2.   A Tentative Suggestion That The Carvings Were Made At Night

In my Photographer's Statement note I refer to the academic work proving the existence of faces and designs among the Avebury stones.   These artifacts were typically created so that they would become visible to worshippers by catching the light at particular times of day and seasons of the year. This would have caused a problem for their sculptors - a problem of consistent lighting while they carved.

Sarsen is notoriously hard to work, and I imagine that even a small amount of carving would have taken days, if not weeks, to create.   During this extended period the sun would move across the sky repeatedly every day, casting light from continually changing directions all the time.   How would this moving daylight enable the sculptors to create work intended only to be read when illuminated from one specific direction?   To put it another way, any carvings intended to be concealed/revealed in this way could only have been made under the same lighting conditions they were intended to become activated by - and sunlight cannot consistently provide the sculptor with light from the right direction.

This leads me to suggest that the most precise carvings may have in fact been made at night, by the light of open fires or burning torches/lamps mounted on wooden stands.   These nocturnal lights would have been carefully placed at the specific position and/or height needed to cast light onto the stone being sculpted as if coming from the sun at the required time of day/season of the year.   The sculptors would have then taken as many nights as they needed to complete their carving.   Such work would have been particularly suited to the winter half of the year - lots of darkness allowing the artificial lights to show up the stones adequately, and the absence of farming activity potentially freeing up workers to shape the stones.  

I can imagine that the flickering light would have made the emerging carvings appear alive as they appeared under the sculptor's hand, an awe inspiring sight for anyone reverently watching the process.