AN ABERDEEN University archaeology researcher has found what could be the remains of a rare Iron Age broch on a small island in a loch near Whiteness, on Shetland mainland.

Michael Stratigos, a researcher from the University of Aberdeen studying for his PhD, found the remains on one of the three Holms of Hogaland islets in the Loch of Strom.

Scotland is the only country in the world to feature brochs – drystone towers dating from the period 100BC to 100AD – and scientists disagree as to how many there may be.

Shetland has possibly the largest concentration, with perhaps a hundred or more, but the new find is exciting archaeologists because of its location on a small islet in a loch, similar to a crannog. It could provide the missing link between brochs and crannogs, according to its finder.

Stratigos runs the Scottish Crannogs blog on which he revealed the discovery that appears to blur the accepted differences between brochs and crannogs – artificial islands on which timber or stone forts and houses were constructed for centuries.

He said the majority of the islet is covered by a large mound around 3m high and 16x14m across, with a small circular depression in the centre which is believed to be the internal space of the broch.

Stratigos wrote: “I was tipped off by Claire Christie – who is working at the Shetland Amenity Trust using high-resolution aerial photographs to map Shetland’s Sites and Monuments Record – that there may be a causeway out to the island.

“There were obvious structural features, including coursed stonework and potentially the remains of orthostats or piers, internal divisions within the former structure.

“On the west side of the island, and most exposed to the weather, there appears to be some active erosion, although the rate and extent of this is difficult to know.

“Bedrock can be seen at the edges of island, so it is clear that this islet is not completely artificial, however, it seems likely that a significant portion of the current islet underwater is composed of material transported to the site.

“While not a crannog in the classic sense, it may well prove that sites like this are assuming similar roles as crannogs in Iron Age Scotland.”

In an interview with Shetland News, Stratigos added: “It is difficult to say how well-preserved the site is without taking back some or all of the vegetation, something that would undoubtedly speed up the decay of the site.

“What was clear though is that the south-west side of the island appears to be eroding, as there may be some stonework that relates to internal divisions of space that is now opening up to nothing, the loch having claimed most of whatever structure it related to.

“Return visits over a number of years carefully recording what changes would be the best way to quantify how quickly the erosion is taking place, if any.

“The archaeology team at Shetland Amenity Trust, the group Archaeology Shetland and a national research programme at St. Andrews, Scape, are keenly aware and focused on this kind of work on brochs and all other kinds of heritage at risk of coastal erosion.”

Shetland Amenity Trust archaeologist Val Turner said: “If it’s not a broch and is an Iron Age house, then it’s still significant.”

The island of Mousa in Shetland has the best-preserved broch, which features in Norse sagas and dates from 300 BC.

She added: “The dimensions of this one are roughly comparable with the Mousa Broch, which is always said to be the smallest broch.

“If we’ve got another one which has similar dimensions, then that’s also quite exciting.”