At the centre of the broch we excavated a series of three hearths lying one on top of another. As the second hearth (detailed in our earlier post) became unusable, it was levelled with a thick deposit of ash and rubble and a third hearth complex was built over the top. This was composed of a huge central slab (now fractured and broken) surrounded by closely laid smaller flagstones. At 1.5m by 1.5m, this hearth was the largest of the three. Construction of this hearth was accompanied by another kerb revetment around the south-west quadrant of the hearth, this time with more substantial edge-set stones. These stones were set within a deep cut through the flooring around the previous hearth and packed in with a mix of re-deposited clay and large rounded cobbles.
To the south end of the hearth, the kerb terminated with a large vertical post stone, 0.75m in length, which was held in place with a large quantity of rounded cobbles, pebbles and a broken quern stone. Two similar post stones were uncovered at the north and east. All three were similar in size and shape, and appear to form a surround around the hearth complex. There is also tentative evidence for a stone kerb between these posts.
With the construction of this new level, the hearth complex was over 0.5m deep, with associated floor accumulations to a similar level. It is clear that this third hearth was the last one to be used in the broch: ash deposits spilled from its final use were found spilling onto the surrounding floor surfaces.
Immediately north-west of the hearth was a stone tank or setting measuring 0.7m by 0.8m and 0.55m deep, resting directly on the bedrock. This feature was still in use at the time of the abandonment of the broch. Tank features in other brochs have been interpreted as having been intended to store water, but this example showed no evidence for clay lining or other waterproofing. Alternatively, the stone box may have been lined with hide or other organic material to make it watertight. It was filled with fire-cracked stone, animal bone and shell in a matrix of silty grey clay. The character of this fill, coupled with the proximity to the hearth, suggests that the function of structure was related to cooking or food preparation.
Look out for next week’s post, which will look in more detail at one of the largest artefacts discovered on site: a knocking stone. Make sure you don’t miss a thing by signing up using the box in the right sidebar to get these posts straight to your inbox!