Tuesday, 8 May 2012

The Broch Project at Strathyre 2004

Hidden away at the end of the track through the Forestry Commission car park at the South end of the village of Strathyre within The Loch Lomond and Trossachs National Park is the result of an ambitious project to find the answers to some serious questions regarding the structures known as Brochs.

The location of the Broch in Strathyre is adjacent to the Strathyre suspension bridge (above) and the famous Strathrye 'Beach' alongside the River Balvaig (below).

The Broch is a totally Scottish Phenomenon not found anywhere else in the world. Built principally from Devonian Sandstone 450 million years old some of the finest examples exist on Shetland.  In 1925 a storm revealed the Skara Brae village on Orkney and it's associated ancient stone 'furniture' - it is from this time that Broch's dominated.

The above is an amazing example of preserved 2000 year old craftsmanship on the islet of Mousa part of the Shetland Isles. It stands fully 10 metres high and 8 metres in diameter.  The walls are 5 metres thick - 2m for the outer, 2m for the inner with a 1 m cavity between. The structure is huge and sophisticated in construction containing stone spiral stairs within the walls, ventilation, and window openings, as well as facilities to support internal wooden beams and flooring. Much has been written on Brochs about the who, what, where and when, and the common view is that  they were built as defensive structures. However, nobody has really shown HOW they were built.
Other examples are Clickimin on Shetland and Dun Carloway on The Isle of Lewis.

In 2004 Irwin Campbell, ex- paratrooper and erstwhile master craftsman and member of the Dry Stone Walling Association http://www.dswa.org.uk/ persuaded the Forestry Commission, Loch Lomond and Trossachs National Park and Stirling County Council to agree to build a section of a Broch in Strathyre in order to answer some key questions:

What was the method of construction ?
How much stone was required ?
How many people would it take to build one ?
How long would it take to complete the job ?

With the aid of 20 people, members of the Dry Stone Walling Association and some villagers Irwin set out to answer these questions - and the segment of the Broch that was built is still there to view today.  As is a DVD on the project The Broch

It seems then that round buildings were preferred to angular ones due to the ease with which they could be set out via a central post and a length of string for alignment. The immense walls not only being 5 m thick with a 1m staircase built-in, but the stones were sloped down and outwards to avoid rainwater ingress - to create a 'Batter' with the diameter reducing the higher the structure. No modern tools or materials were used - but Hammer Stones - simple beach cobbles - used as is likely the original builders had access to such implements.

What transpired was an involved and testing project for the participants particularly when the central post which was delivered by the Forestry Commission proved too huge for 12 able persons to lift - and it had to be reduced by a third.

The workmanship of the stone is obvious for anyone who cares to pay a visit, the carefully selected stones were shaped and placed individually and the spaces between packed with 'Harting' - thought usually done by the women and children of the village, so it was a truly communal effort.

The section of Broch that was built is barely 2 m high and is made up of 60 tonnes of stone and took the combined efforts of 20 people.  Thus it was concluded that a complete 8 m high Broch would have consumed over 2500 tonnes of stone and taken 20 people a whole year to build, that is excluding the amount of time taken to quarry and transport the stone - which would probably have taken another year to complete.

Irwin states that this implies a period of stability, and therefore declares that the Broch was not intended as a fortress but as an ostentatious symbol of a Chieftains wealth.

This is a similar conclusion to that arrived at by the archaeologist's who uncovered and rebuilt The Crannog in Loch Tay. . . . .perhaps the subject for another blog . . . . . . .  .