Sunday, March 04, 2007

Re-Purposing Stonehenge

Some months ago, I posted an article about a Michigan man who had worked out a set of techniques that Neolithic people could have used to erect megalithic monuments like Stonehenge. That iconic ring of stone has been the subject of the wildest and most bizarre kinds of speculations for years:

The Wikipedia article referenced above provides a good overview of many of these wilder ideas, so I won't bother with trying to include any here. However, a few minutes of Googling and link-chasing will produce a dismaying number of other sites with views at least as bizarre as those suggested in the cartoon. (I found a totally new one just today, a suggestion that Stonehenge and other megalithic monuments were actually cosmic impact early warning systems.)

Still, the serious question remains: "Who built Stonehenge, and why?" Over the last decade or so I have occasionally spent a little time looking into this. The most comprehensive and sensible explanation I have found is given in archaeoastronomer John North's book Stonehenge: A New Interpretation of Prehistoric Man and the Cosmos. Prof. North (and doubtless several generations of trusty grad students) have done an enormous amount of research reconstructing orientations and alignments of hundreds of Neolithic stone and earthen monuments thoughout northwestern Europe. Briefly, North's research confirms that these monuments reflect the development of several different religious practices over the course of millennia:
  • a star-oriented cult that placed emphasis on the ceremonial observance of star risings and settings that occurred daily
  • a moon-oriented cult that placed emphasis on ceremonial observance of the complicated pattern of lunar risings and settings that repeats itself over an 18.6 year period
  • a sun-oriented cult that placed emphasis on ceremonial observance of the rising and setting sun at soltices and equinoxes that occurred annually
The many earthen barrow and ditch structures in England and surrounding countries mostly reflect the first cult. The megalithic structures reflect the second two cults. Stonehenge, in its final form, is best suited for sun ceremonies, but has strong features associated with the lunar cult as well. Of course, both cults might have been active co-temporaneously at different points, as well as a few star cults as well.

Some years ago English astronomer Gerald Hawkins caused a great stir with his well-publicized books claiming that Stonehenge was an astronomical observatory or 'calculator', used to predict astronomical events. Although there is certainly an aspect of prediction associated with the monument, North's interpretation points more to its religious uses. This can perhaps best be seen by considering the basic alignment of Stonehenge, which is oriented along a very precise northeast-southwest axis. You can see in the photo to the right the so-called 'avenue', outlined by ditches, leading in a southwesterly direction toward the center of the monument. Hawkins claimed, and supposedly demonstrated, that Stonehenge was oriented towards the rising sun on the day of the summer solstice. If you stand at the right spot in the ring at dawn on that day looking down the avenue, you can in fact see the sun rising over the 'heel stone'.

However, there are some problems with this claim in being the principal way to use Stonehenge for observations. One is that the avenue slopes downhill towards the northeast. Seeing the sun rise at a particular spot on the horizon is totally dependent on whether there are trees at the horizon line, and how tall they are. A change in height of these trees would cause the apparent point of first visibility of the sun to shift left or right.

An even more serious objection to this theory is that only a very small number of people could stand at the appropriate viewing spot to see this supposedly important event. While there are certainly antecedents in various world religions for events that only the high priests can observe, from a believer's point of view, it is much more satisfying to see the event for oneself.

Prof. North noted that one can turn the orientation around 180°. Standing on the avenue, looking southwest, uphill toward the monument, one can also see the setting sun at the winter solstice. This claim has a number of advantages. The first is that, since you are looking uphill, the stone ring forms an 'artificial horizon' which precisely defines the moment of sun's last visibility. There is no vagary depending on the presence, absence or height of distant trees. Moreover, there is room on the avenue for literally thousands of observers, all of whom could participate in watching this event. Finally, based on other archaeological evidence at many other sites, it was much more important for this ancient cult to pay attention to the setting sun at the winter solstice, because it effectively defines the end of the solar year. Sunrise on the next day begins a new year, with each day growing longer and more alive, as it were.

Stonehenge was built in stages, from 3100BC to 1930BC, with some evidence of wooden structures being used on the site as early as 8000BC. The builders were pre-literate, although obviously energetic and well-organized. Other sites in the general area show settlements big enough to house thousands of inhabitants, as well as many large farms. Although theses people lacked metal-working and writing skills, they must have had a robust social structure and a high culture. Building these monuments was important to them, considering how much work it took to cut and move the stones, and to dig the huge amounts of earth involved, all with stone handtools.

By the way, the Druids had nothing to do with building Stonehenge. They didn't show up until 300BC, over a thousand years after the last addition to the monument. And the 'neo-Druids' who dress up and do weird things in the stone circle on Mid-summer's Day are sadly mistaken, or just silly. Real druids tended to shun flat open spaces like the Salisbury Plain where Stonehenge is, and performed their rituals in groves or hilltops. Still, they might have used the monument some, since they were concerned with solar events like solstices.

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