Introduction

The Chambered Cairn of Bookan is located on central Mainland, Orkney on the ridge about 1km north-west of the Ring of Brogar, overlooking the Brodgar peninsula. The site lies within the Inner Buffer Zone of the 'Heart of Neolithic Orkney' World Heritage Site.

The site has always seems a bit of an enigma. The apparent simplicity of its layout and similarities to some early forms of chambered cairns led Audrey Henshall to use the site as the type-site for a sub-group of her 'Orkney-Cromarty' group of chambered cairn. The Bookan-type of tomb was seen as a local adaptation of the early tripartite style of tomb, and considered to be early Neolithic in date. Henshall however noted that the description of the pottery recovered from the tomb in the 19th century was more characteristic of late Neolithic Grooved ware than early Neolithic styles of pottery.
The assignment of Bookan to the early Neolithic is further called into question with the discovery and excavation of the nearby late Neolithic settlement at Barnhouse by Dr Colin Richards in the early 1990's. The angular nature and symmetry of the archietecture of the chamber at Bookan bears strong similarities to House 2 at Barnhouse.

Ring of Brodgar from Bookan

Petrie's plan of Bookan of 1861

Petrie's sketch of Bookan

Excavation starts with high expectations...

Excavation started with high expectations and a feeling of excitement. We hoped that Farrer and Petrie had left some unexplored deposits that would supply dating material and other evidence they had overlooked. Trenches were laid out over the mound in order to provide cross-sections through the mound, and examine some of the chambers Petrie had noted, and also the passage and the make-up of the surrounding cairn material. Although mainly dry, the wind on site in such an exposed position, even in the middle of an Orcadian summer, made work unpleasant at times. We soon however had the remnants of turf removed from the trenches and started cleaning up the exposed deposits. In Trench A, a wall was uncovered running across the site from E-W in roughly the area were Petrie had planned the outside end of the passage. This caused great interest, as it appeared that in fact it continued across the end of the passage, so it seemed that some of the lintel stones of the passage would still be in place. Further north in the area of Petrie's central chamber a loose stony fill was encountered. This had to be part of Petrie's backfill of the site. That was confirmed with the discovery of some beer bottle glass and fragments of a clay pipe. During removal of this backfill, other upright stones, as planned by Petrie, started to appear and also part of a large flat slab at the presumed end of the passage. This was initially interpreted as the remnants of blocking to the passage, but was later to reveal itself as a single large flat slab covering the passage floor. At the south end of Trench A, another wall was uncovered running across the trench near the edge of the extent of the cairn material. This was interpreted as a revetment wall to help stabilise and keep the cairn material in place, and was presumed initially to relate to the construction of the tomb. How wrong we could be!!
After planning and photography we started to remove some of the cairn material in front of the presumed wall forming the end of the passage, expecting to find the bottom of the lintel and hopefully the entrance to the passage. Instead we found that the 'lintel' stone was only the upper course of a stone wall that seemed to sit on top of the passage. This discovery implied that 'Petrie & Co' had not excavated as far as their plans implied. They must have just uncovered the top of this wall and mistaken this for the end of the passage. As more of the cairn material was removed another wall was found running across the trench. This would again seem to be another revetment.

In Trench B work in the vicinity Petrie's NW side chamber started to reveal a very mixed yellow clay that rose up to the north of the cairn. If Petrie's plan was right this was obviously his backfill again. It didn't take long to carefully remove this and the edge of what we presumed would be the back wall of the chamber started to be uncovered. Katie and Sarah, two of the Manchester students then became very excited, as a group of bones were uncovered. Were they human; were they still in situ or had Petrie left them in place? It was known that at another site Petrie had excavated on the Holm of Papa Westray, that when Anna Ritchie re-excavated the site she discovered Petrie had left bone behind and appeared to have been only interested in skulls. Although the teeth Sarah and Katie found appeared human the rest of the bone was very fragmentary and needed confirmation that it was human. Daphne Lorimer, a local human bone specialist (and chairman of OAT- very handy!!) was called and kindly quickly confirmed they were human and probably represented the remains of a single individual, possibly female. Careful cleaning around the bone exposed their limited extent, before they were photographed and carefully lifted. These bones should be able to provide us with a radio carbon date for the use of the tomb.
Further to the west in Trench B Colin and Angus started to clean back down the cairn material in the hope of finding revetments equivalent to those found in Trench A. At first nothing really showed up apart from various mixed deposits that appeared to be spoil deposits from the 1861 excavations. However, although not as well preserved as the walling/revetments found in Trench A, two stone alignments were found which seemed to correspond with those in Trench A. By 'joining up the dots' we were able to estimate what we thought at the time was the original size of the cairn as being c.17m in diameter.

Trench locations

Recovery of human remains

Revetements

Excavation goes on...

Back in Trench A the continued removal of Petrie's backfill within the tomb revealed the remnants of possible flag-stone flooring that may have originally covered the central chamber. On the whole though most of the chamber floor appeared to be in situ natural boulder clay. Three features however were noted dug into the natural. Their positions suggested that they might be the cuts made for the insertion of orthostats, partly defining the east side chambers. These orthostats were missing from Petrie's sketch and plan. On excavation these did in fact turn out to be slots for orthostats that confirmed that the E side of the tomb was a mirror image of the better preserved W side. Careful excavation revealed not only the slots but also the packing stones in situ. The slot on the N side of the trench also revealed in the trench section a very neat cross section of the way the NE chamber, had been constructed, and by implication the construction sequence for the whole tomb. The section showed that basically the site had first been cleared of topsoil down to natural; cuts were then made for the insertion of the main upright stones; the orthostats were then inserted and packed around; the side chambers were then paved and then finally the outer wall was built, partly overlying the paving. There was however one slight complication in that Petrie's plan also showed smaller orthostats, between the main ones. Audrey Henshall had interpreted these as threshold slabs at the entrance to the side chambers. There was however no sign of a cut for one between the central chamber and the SE side chamber. This problem was to be neatly resolved by the excavation back in Trench B.
In Trench B with the removal of the human bones work continued in the NW side chamber. It was now clear that the bones had in fact been left on top of a very large slab which had originally been part of a flagged floor in this chamber. There was however no sign of the neat back wall of this chamber as Petrie had shown, only a rather rough pile of stones. It would appear that Petrie had used a little 'artistic license' in his sketch! The removal of the remains of Petrie's backfill however did confirm the presence of 3 revetments and very freshly quarried looking cairn material much like that in Trench A. A wall line was also found to the E of the innermost revetment just behind the flagging to the NW side chamber. Suddenly it all seemed to make sense. This new wall line was in fact the outer wall face of the inner skin of the tomb and the inner wall face forming the back of the tomb had been robbed out sometime in prehistory. The "rough pile of stones" mentioned above was part of the wall core. This did however question the relationship between the inner skin of the tomb and the revetments. This was resolved back in Trench A. The question of the missing orthostat/threshold cut was resolved in the NW side chamber. Here this threshold stone was still in place and excavation revealed only a very shallow cut for its insertion. A similar cut for the missing threshold stone in Trench A was probably obliterated during the 19th century excavations or in prehistory when the stone was removed. The shallow cut coupled with the close fit of the remaining threshold stone between the two uprights may suggest that this in fact was not a threshold stone and not meant to be permanent but rather was inserted as a removable 'doorway' or blocking stone for access into the side chamber, as at Maeshowe.
Back in Trench A the relationship of the inner wall and the revetment was resolved. Removal of the innermost revetment, (the one which Petrie had thought of as the outer end of the passage) revealed that this in fact had been built on top of a thick clay levelling layer, which in turn obscured the actual inner wall of the tomb and also the entrance passage. It now appeared that we were in fact not dealing with a single structure but at least two major phases of construction!!!! It was now clear that the revetments were later additions to quite a small tomb/structure. The revetments had also only been built after the original tomb had either fallen into disrepair or perhaps been deliberately slighted. The removal of the clay foundation for the inner revetment also revealed the full extent of the passage, c.2m long by 0.5m wide. Petrie had obviously not fully explored the passage and had based his measurements on the inner end of the passage. The east wall of the passage was beautifully built and remained intact for 8 courses high. The west wall was in a less well preserved state partially we think because it was built on the very edge of the large slab which formed the passage floor. The east wall was built sitting squarely on this floor slab. The removal of most of the later cairn material (between the later revetments) beyond the passage entrance revealed collapse from the original tomb wall that covered a small area of paving just outside the entrance.
Only at this stage could we then piece together a full history of the site. At this initial period of analysis it seems that the phasing for the site is as follows -

• Stripping of topsoil under the tomb down to natural
• Excavation of slots for main uprights, followed by erection and packing of orthostats
• Excavation of shallow slots for, shaping and erection of removable entrance slabs to side chambers
• The floors of the side cells were levelled and paved
• Laying of large flag to form the floor of the entrance passage
• Paving of central chamber
• Yellow clay deposited to form foundation/ damp proofing for the construction of the outer wall
• Construction of passage and outer wall around the chambers. The back walls of the side chambers being built off the flagged floors of the side cells. Provided the symmetry of the structure is replicated throughout the structure, the original tomb would have been slightly oval in plan, and measured c.6.6m N-S by c.5.2 E-W (figure 6).
• Presumed construction of roof.

With the end of the excavation the painstaking work of post-excavation now begins with various specialists looking at the material and samples recovered from the site. No doubt the final phasing of the site will be refined and with the possibility of absolute dates being obtained from the different phases it is very exciting to see how the site will fit into the overall scheme of the Neolithic in Orkney. One of the obvious questions is will the dates still assign the primary tomb to the early Neolithic or will it indeed be later. My feelings are at present that it will be later. In many ways the layout of the tomb would seem to reflect the later Maeshowe type tomb rather than the earlier Orkney - Cromarty style of tomb. Access to side cells from a central chamber and the use of possible removable doorways would seem to reflect the Maeshowe style of architecture, however the use of upright slabs is also seen in earlier styles of tomb. Are we in fact seeing at Bookan a transitional style of tomb in the evolution between the two styles. . . only time and further analysis will tell !!!!!!

Cut for lost orthostat

Passageway with central chamber beyond

Final planning