3. Maes Howe tombs
This type of tomb is unique to the Orkneys and, even there, only 12 of them have been identified— principally on the basis of their size and contents, which includes Grooved Ware instead of Unstan Ware. Of the dozen, seven have been excavated to some degree or other. In most of them, the internal chamber is rectangular with a high ceiling but in one case it is square and in another polygonal. They are also characterized by small openings in the walls that lead to cells. The superstructures are normally circular in plan and can be quite large.
There is considerable variation in the length of the burial chamber but normally the width is between 1.4 and 1.8 metres. The longest is Holm of Papa Westray South (ORK 22), which is 20.4 metres long and has no fewer than 14 cells. The walls were made out of larger slabs and blocks than the Orkney-Cromarty cairns. Some of those lining the lower parts of the walls can be quite massive. This is because they have to support heavy lintels over the entries to the cells and the passageway. Above that level, the slabs are long and thin and are laid in slightly overlapping courses, a technique known as corbelling, in order to reduce the span of the roof to something between 0.5 and 0.9 metres. A good example can be seen at Cuween Hill (left). The roof was undoubtedly composed of stone lintels laid crossways—at least that is the case with the two instances where some of the material survives, at Quanterness (ORK 43) and Wideford Hill (ORK 54). The height of the chamber could be anywhere from 2.4 to over 4 metres.
Overall, the level of craftsmanship is exceptional. The end and side walls are bonded into each other and, in some tombs, a good deal of care went into making the corbelling appear as smooth as possible. The interior layout of some tombs were clearly planned on principles of symmetry with a balance arrangement of chambers (Quoyness and Quanterness, for example).
The cell entries tend to be small (from 0.6 to 0.73 metres high and from 0.4 to 0.7 metres across). The cells themselves are irregular in shape—with the exception of Quanterness, where they are rectangular. They range in size from about 1.2 by 0.8 metres to about 3.4 by 1 metre at the base and can be anything from 1.7 to 2.2 metres high.
The layout was designed to be compact, so that they fit within the roughly circular cairn core of the superstructure. The latter consisted of one or more casings of loose stone, each held in place by a revetment wall. Today, there is a considerable amount of stone beyond the limits of the wall—but does it represent the original limits of the cairn or tumble from the superstructure? Davidson and Henshall believe the latter and hold the view that the outer revetment was also the outer wall of each cairn and that it stood almost as tall as the height of the chamber. On the other hand, Colin Renfrew who excavated at Quanterness believes the revetment was hidden beneath the slope of the cairn.
The entrance passage could be as much 10 metres long or more and ran at right angles to the main axis of the chamber. It was low and narrow, so that you had to stoop or crawl into the tomb as you crossed into another world. The stone blocks used for the walls were often quite large, as were the lintels used for the roof, and the outer part of the passage was often paved. Since they had to be reused repeatedly over the years, it was necessary to be able to close and reopen the tomb. There is evidence that some of them were walled across while at Maes Howe an enormous stone plug was used.