Our previous post examined evidence for the construction of the broch. Today we move onto evidence relating to the earliest phase of occupation of the broch.
At the centre of the broch were the remains of three successive hearths, layered on top of one another. The earliest surviving hearth had been constructed on a thin layer of flooring deposits which most likely comprised organic materials such as rushes, reeds and grasses laid down as flooring. Lain directly onto this early floor was a flat sandstone flag hearthstone 1.35m in length and 0.75m wide; the stone was heavily heat-affected, leaving it fragmentary and fragile. It was retained in place on the east side by a large, fragmentary edge-set stone, similarly heat-damaged. It is likely that this first hearth was replaced as it became fragmented through use and as the surrounding floor deposits accumulated to the extent that they began to envelop the hearth.
The composition of the floors themselves was difficult to determine during the excavation since, for the most part, they were represented by highly decomposed organic silts and clays, typically containing frequent charcoal flecks and fragments of burnt bone as well as patches of inorganic sand, clay and lenses of orange/yellow peat ash. However, flooring was well preserved in some places, with woody fragments and fibrous organic material surviving. The floors were apparently refurbished repeatedly: ash from the hearth was spread across the floor, probably on an ad hoc basis whenever the surfaces were deemed too wet or foul to be serviceable. Analysis of samples collected from the floor sequences will provide more information about these processes in due course.
At some point, either during the use of this hearth or during the early use of the secondary hearth, a flagstone path was constructed between the northern edge of the hearth complex and the entrance passage, covering a narrow drainage channel. The floor at this time had built up to a depth of around 0.15m of layered organic matting, peat ash and clay. It is possible that waterlogging and puddling of this build-up led the requirement for better drainage, especially across the frequently traveled route to and from the entrance. Although this drain did not have any clear path for outflow, it did prove useful during the excavations, efficiently draining the water from the surrounding floor deposits while we worked. This feature does not appear to have been in use for long, though, since it was overlain by the frequently replenished floor deposits.
Our next post will look closely at a drystone-lined lower passage tentatively interpreted as a souterrain or storage chamber. Check back next week for more on this intriguing feature, or use the box in the right sidebar to sign up to receive blog posts straight to your inbox!