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Brochs are amongst the most spectacular of eroding coastal archaeology, and in the course of SCHARP, we have seen and recorded quite a few of them. Many thousands of these towers of the Iron Age would once have been an impressive sight along the coasts of Northern Scotland, Orkney, Shetland and the Western Isles.
They were generally built around 200BC (although some are earlier) in coastal locations (although not always), and were occupied for a very long time – in some cases for up to 1000 years.
The defining feature of a broch is a massive encircling double wall. This photo looking down into the broch of Mousa in Shetland, taken by Kieran Baxter, shows the classic double walled broch construction.
People re-modelled brochs over these long timescales. It looks like some of them were transformed into sort of super wheelhouses during their lifetime. Here are two great examples from Shetland at Scatness and Levenwick.
We think that the site, revealed in 2012 at Channerwick in Shetland has the form and dimensions of a broch with wheelhouse features inside the walls. Archaeologists have excavated a great many brochs and they have been studied intensively since the 18th century.
It is interesting to see ideas about their purpose and who lived in them change according to accumulating evidence and the shifting world views of our own society. Despite centuries of intensive research, two of our brochs – Channerwick in Shetland, and Lopness on Sanday are NEW discoveries.
This is where coastal erosion has such a dramatic part to play in the revealing of new information about our past. In fact, in both of these cases, the brochs must have been eroded more than once. The current erosion has stripped away vegetation and slumping to re-expose the remains, which may have been last seen too long ago to make it into historic records. Erosion also reveals new information about apparently well-known sites. In this scheduled ancient monument of Sna Broch on Fetlar in Shetland, the broch tower structure is long gone.
However, in the sea-sliced section through its monumental defensive banks soils that pre-date the construction of the broch have been buried and preserved.
In waterlogged deposits at the bottom of the defensive ditches, preserved plant material can be seen with the naked eye.
Deposits like these have the potential to contain very detailed information about the landscape and environment from when before the broch was built into its early use.
Later on in the summer, we hope to clean, record and sample the half-sectioned broch at Channerwick. In this extraordinary site, because the sea has exposed the broch and all its contents, we can quickly gain a good understanding of the relationships of the structures, and can access deposits from the very beginning of the site’s history to the very end.
Another good example of how coastal erosion can present opportunities for new discoveries and knowledge.