Broch
|
|
The Broch is an Iron Age round tower fortification type unique to Scotland.
The origin of brochs remains a mystery. Some archaeologists believed the brochs were built by an influx of broch builders who had been displaced and pushed northward during the Roman invasion of Britain. However, this theory has been largely disproven and current thought is that they were built by itinerant (travelling) craftsmen since so many were built to almost the same exact design. The youngest surviving broch at Mousa dates from 100BC to 100AD with most being older. The distribution of brochs is centred on north west Scotland although isolated examples occur in the borders and near Stirling.
Early in the use of a broch (from the middle of the 1st millennium BC until the early 3rd century AD) they would be used purely as defensive structures, places of refuge for communities and their livestock. As the Iron Age slowly gave way to the early Medieval period, however, it seems the defensive value of the broch design was lost. They became the Stately homes of their time, objects of prestige and superiority for rich merchants.
A typical broch is 20 metres in diameter, with 3 metre thick walls. On average, the walls only survive to 4 metres. More often than not, the walls are hollow, containing flat storage spaces (called galleries or cells) and steps to higher floors. Beside the door, it is normal for there to be a cell breaking off from the passage into the central space; this is known as the guard cell although there is no evidence it had any defensive value. However, it has been found in some Shetland brochs that guard cells in entrance passageways are close to large door-check stones.
On the Orkney and Shetland Islands there are very few cells at ground floor level. However, brochs in this region have scarcements (ledges) which would have allowed the construction of a very sturdy first floor.
Scotland_Glenelg_broch.jpg
Brochs were always placed in locations which were easily defended, close to arable land and a source of water (many have deep wells or natural springs rising within their central space). They are often built beside the sea and on the site of previous dwellings such as roundhouses.
Some good examples of brochs on Shetland are Mousa Broch (the walls here are fully intact, standing some 18m high), at Clickimin in Lerwick, at Levenwick and in Culswick. Elsewhere, in Glenelg (a galleried dun can also be seen here) and at Doune Carloway on Lewis. The best brochs in the Orkney Islands are at Gurness and Midhowe.
The Shetland Amenity Trust list about 120 sites in Shetland as candidate brochs.
The skills involved in broch building are currently being explored by drystone dyker Irwin Campbell (http://www.brochbuild.co.uk/).