Stonehenge Solved Its Three Observatories, Who built them, How and Why

As we will see in chapters 7, 8, 9, 21 and 23, at the time of the Early henge, the apparent paths of the Moon, as seen in the British Isles, were not as we see them today. For several centuries the paths included passages overhead and to just either side of this. The prevailing low level of technology limited observations to these high angles of elevation anyway, although to a far lesser extent, some were directed at low angles towards the horizon.

The Early henge was for observing changes in the apparent paths of the Moon. The methodology employed was observation of the shadow of a near-vertical pole, the butt end of which was stably secured with backfill, or packing, in a pit Fig 5. When first set the pole was angled to cast nil shadow at a fleeting instant when the Moon passed overhead, or nearly so. At lunar month intervals thereafter, if a change in the path occurred, shadow of the pole's free end appeared on the surface of the backfill at the pole's foot. After another month, continuing change would have seen the shadow lengthen at this point. However, 28 days, or more appositely nights, was too long for observers to wait, so more than one of these arrangements, or 'stations', was in use at any one time. For example, 7 stations could result in waits of only 4 nights to discover if change was occurring.

When a setting ceased to be workable, as an example, when the line of the minimum shadow had become too blurred, a pole could be reset by nudging it to a new angle and retamping the packing. But after a few such resets the arrangement became unstable and the pit had to be emptied of packing and reset from scratch; an outcome of this activity was progressive enlargement of the pit. This methodology was widely used in the British Isles in the absence of hard rock in the terrain, and commonly so on free draining sub-strata, notably gravel and chalk. Upright stones were used when hard rock prevailed, the minimum shadows being marked by small stones, (although an alternative arrangement was sometimes used: that of placing upright stones at the shadow extremities of the tops of uprights placed in a circle and subsequently removed (i)).

There were several reasons for the particular location of the Early henge: the ground on underlying chalk was well drained, the site was elevated and free from flooding, and it was flat and sloped only very slightly downwards to northeast. It was also close to its initiators' possible settlement at Durrington Walls 3km (1.5m) distant to northeast along way SU 1543-1 (see Fig 60) (ii). Lastly, but by no means least, it was at the intersections of several ways and thus widely accessible in the district, Fig 6. Prior to construction there was one distinguishable man-made feature on the site; this was a waymarking pit on the south margin of way SU0637-1 (iii). Its spoil is speculated to have been utilised for the creation of a unique waymarking mound some 500m (550 yds) to northeast, down a slope and on the same side of the way. An accompanying, lesser feature, was a patch of insecure ground about 2m (7ft) east northeast of the pit, but its cause and nature are not known.

Later on in the henge's life it would seem that some visitors to the site from the southwest and travelling along way SU0637-1, unwittingly passed through it. To remedy this, a termination pit was dug on its line a few metres northeast of the waymarking pit. Shaped like half a pear, its cut face upwards and level with the ground, it was about

1.2m (4ft) deep. People walking along the way walked into its neck and were quickly brought to a halt. This could be taken to imply a state of trance, if not nocturnal difficulties, or vegetation obstructing vision. Later in the narrative it will be seen that all three of these features: waymarking pit, unfirm ground , and the termination pit, led to profound consequences.

Creation of the henge was founded upon an annular ring of about 310 degrees. Its outside diameter was about 118m (130 yds), its width 12m (13yds). It consisted of an exposed clean chalk surface, the gap between the 'horns' being orientated towards northeast, and left untouched. The underlying chalk was revealed by scraping off the thin topsoil and turf, in an outward direction. This resulted in a bank of spoil around the circumference, the extent of which for a few metres to south southeast was constrained by the north margin of SU0340-1. An entrance, or access from the way, was to be situated here. Today this bank is conventionally called the 'counterscarp'. The purpose of the ring was to ensure that stations dug on it were of completely uncontaminated chalk throughout their operational lives.

The stations appear to have been dug in groups of four or five in straight or slightly curved lines positioned between the outer circumference and the ring's centre-line; thus the spoil, or packing of the pits, could be placed inwards to remain uncontaminated on clean chalk fig 5. When, because of cleaning after successive resets, the stations became too large for ease of use, the operators commenced another group of pits elsewhere on the ring. Between the horns of the ring and a little to southeast of SU0637-1 was a pair of upright Chilmark stones about 8m (28ft) apart, aligned within a degree or so east-west. Their function is not obvious but it is speculated they were direction reference markers, perhaps relating to an astronomical event perceived at the horizon.

It would appear that when there was no space left around the ring for more pits, the operators were so reluctant to discontinue, or restart elsewhere, they managed by working with larger and larger pits until, inevitably, these broke into one another, Figs 7 and 8. When this occurred the intervening feathered edges were removed with the result that irregular trenches were formed. Stations were made to function on the bottoms of these, even when they were of uneven heights as the consequence of adjacent pits having different depths. The original pit diameters are speculated to have been about 1.25m (4ft) hosting the butts of poles, say 2m (6ft) long, whereas the trenches were nominally 3m (10ft) wide at ground level. This surprising scenario may have been because the operators noticed the flanks of the trenches served to reduce the level of ambient light, thus improving the sharpness of the observed shadow. The persistence in continuing to use the site, not withstanding its inconveniences, and also the importance of the putative direction reference markers, are demonstrated at the horns. Here, without first bothering to scrape off the topsoil and turf, as the initiators had done, the stations were extended between the two upright stones into the gap of the horns, to terminate at the margin of SU0637-1. This also suggests the latter's continuing use. The stations on the opposite horn were also extended but only by a single pit, this also serving to terminate SU0435-1 from the northeast.

Thereafter the site was abandoned with some 80 worn antler picks left behind in the half of the ring excavated. Nothing else and no vestiges of poles have been found; after allowing for erosion, one supposes anything of possible use was carried away. The site must have quickly become verdant and it lay derelict and ignored for about 700 years, when it was seen to be an ideal site for something much grander, as will soon be shown.

The evidence for the five ways, at the intersections of which the Early henge was created, is secure (iv). For many centuries ways were the infrastructure that linked settlements, including those of the very much later Iron Age. While remaining incomplete, the analysis already yields the following related Iron Age monuments, the following list using the Early henge as the reference base.

SU0340-1 to west: Yarnbury Castle
SU 0435-1 to NE: Sidbury Hill; to SW: Grovely Castle
SU0637-1 to NE; Fosbury; to SW: Stapleford Castle
SU1543-1 to NE: Durrington Walls
SU1142-1 to west: tumulus at Tilshead Down

One might conclude that while the creators of the henge may have lived at Durrington Walls, people at Yarnbury Castle were major users.