2 miles West of Brinian, Rousay, Orkney, Scotland.
The Knowe of Yarso is situated just over a mile to the West of Brinian on the island of Rousay, along a stretch of the B9064 which is teeming with ancient monuments, including the Broch of Midhowe, and the cairns of Midhowe, Blackhammer, and Taversoe Tuick. Unlike the latter two, it is not located immediately off the road but requires a modestly demanding climb of about half a mile up to some 300 feet, although my memories of its severity may be somewhat coloured as I was encumbered with a bicycle at the time, and it is not at all easy to push one up the narrow path.
Originally thought to be a Broch, its excavation in 1934 revealed the Knowe of Yarso to be a stalled cairn aligned on a South-West to North-East axis, broadly rectangular in shape with rounded corners. It has been dated to around 2,900 BC, but may have been in use for a further millennia before being sealed. Like many of its neighbours, Yarso was robbed of most of its original roofing material over the centuries, causing much stone and soil debris to collapse into the chamber, which was gradually overgrown with a mound of grass and heather measuring 62 x 32 feet. Clearing this away, the excavators found that the cairn was originally 50 x 25 feet, and consisted of an inner and outer wall laid on a plinth of flat stones which protrudes about 3" beyond the extremities of the latter. The outer wall is more or less 3 feet high around the circumference with the entrance passage cutting into the centre of the South-Eastern face. To the left of the entrance the dry stone walling slopes at an angle of 15° from top right to bottom left, with the stones to the right of the entrance mirroring them. The inner wall is situated 2½ feet inside the outer and stands about 5 feet high with its stones laid flat.
A protective concrete dome has since been built over the remains of the cairn to protect it from the elements, with a grassy mound laid on top and skylights set into it to illuminate the interior. Passing through the fairly large door at the South-Eastern end, vaguely reminiscent of an air-raid shelter, one is immediately confronted with the outer wall and its sloping stonework either side of the entrance. The passageway is 13 feet long, and although the roof is now missing it would have originally been about 3 feet high. Beyond this is a 24 x 6 feet long chamber divided into four equally sized compartments by means of three sets of flanking uprights. Another pair of uprights sit against the near side of the chamber wall to divide it from the passageway, and these together with the next two sets are between 4 and 6 feet tall. The western-most pair are less than 2 feet high with two small stones set between them, forming a sort of step. This last compartment, which features an end slab set against the far wall, is probably not a compartment in its own right, but a sub-division of the previous one.
The cairn was found to be rich in human remains, with no less than 17 skulls, almost all of which had been separated from the skeleton, and the bones of at least 29 adults being identified. The passageway and all of the compartments contained some fragments, but the overwhelming majority and all of the skulls, neatly arranged and facing inwards, lay in the western-most compartment. A considerable quantity of wild and domesticated animal bone was found, above all fragments of 36 red deer, but also oxen, sheep, limpets and a large dog. Many of the human and animal bones had been scorched, and as there were traces of ash and soot, and many of the wall stones were reddened and cracked from heat, it is clear that fires had been lit inside the chamber. This may have been a practice of some later people, however, as what few pottery fragments were found in the cairn were not of its period. Finally a number of tools were discovered, largely in the form of flint scrapers, but also there were three flint knives, two arrow heads, and several pointed tools fashioned from animal bone.
Archaeology Data Service - Excavation Report