New techniques reveal more hidden treasures on the Hill of Tara

New techniques reveal more hidden treasures on the Hill of Tara

5 Nov 2002

Elevation map of the Hill of Tara, Co. Meath, with geophysics imagery (black and white) overlaid. One of the most stricking features exposed by the geophysics data is a circular enclosure (a 'henge enclosure') equivalent to the size of Croke Park (170m North to South), which is believed to date from around 2500 BC. It comprises a 4m wide ditch, possibly up to 3m deep, on either side of which are great 2m wide pits. These pits probably held around 300 wooden poles between them.

At least 100 new monuments have been discovered on the Hill of Tara, thanks to the deployment of non-invasive exploratory techniques. Geophyscial survey allows archaeologists to record the magnetic properties or electrical resistance of the soil, which is permanently altered by human activity, therefore proving that people once inhabited the area. For example, a bonfire or a burial will permanently enhance the magnetism of the soil around it. Similarly, a buried wall will act as a barrier to the movement of electric current passed through the soil and therefore significantly increases its electrical resistance.

Mr Conor Newman and Mr Joe Fenwick of the Department of Archaeology at NUI, Galway and the Discovery Programme, which is funded by the Heritage Council, have been researching Tara since 1992. The earliest monuments at Tara date from around 4000 BC. Close to 30 monuments had been recorded prior to the deployment of geophysical survey, which has greatly aided the research process and facilitated the discovery of approximately 100 additional monuments.

In three field seasons since 1999, the team at Galway has increased the geophysical survey area on the Hill of Tara by more than 13 hectares, making this by far the most extensive geophysical survey ever undertaken in Ireland. Plans are in place to survey the rest of the state-owned part of Tara in the next few years.

A host of new and interesting features have been revealed in the work so far. One of the most spectacular finds is a huge oval enclosure, equivalent to the size of Croke Park (170m North to South), which is believed to date from around 2500 BC. Referred to as a henge (see illustration), it comprises a 4m wide ditch, possibly up to 3m deep, on either side of which are great 2m wide pits. These pits probably held around 300 wooden poles between them. This oval enclosure encircles Ráith na Senad or Rath of the Synods and takes in the whole of the present day churchyard. It also includes a passage tomb known as the mound of the hostages. Like most of the monuments on Tara this is a temple or sacred compound of some sort.

A full report on this monument and others found in the course of the survey has just been published in the 6th volume of the Discovery Programme Reports and is available from the Discovery Programme and the Royal Irish Academy. The Discovery Programme has produced a detailed map of all of the monuments on the Hill of Tara using a combination of the geophysical survey finds and topography.

Aerial view of the Hill of Tara

The topography map is in digital format, which means it is fully interactive. It can be interrogated and manipulated in order to reveal features that are otherwise barely visible. These techniques have confirmed that many of the monuments built on the Hill of Tara incorporated older monuments into their fabric. This allowed some of the ritual and historical importance associated with the older monument to be included in the new structure.

"Every new monument discovered at Tara adds to our understanding of the development of the complex," said Mr Newman. "For the most part, the monument builders of each generation observed, preserved and accommodated all of the older ones in a way that contributed positively and sensitively to the developing authority of Tara as a place apart," he added.

Close to half of the State-owned land on the Hill of Tara has been examined using geophysical survey so far and plans are in place to continue with this research and to survey the rest of the hill. However, much concern has arisen lately about the proposed route of the M3 motorway, which if approved, will pass right along the eastern foot of the Hill of Tara, crossing an area intimately connected with the great royal complex. This area also boasts an impressive concentration of archaeological monuments. "It is a reckless dereliction of our role as guardians of our common cultural heritage to drive a motorway through it," said Mr Newman. "If you disassociate a society from its past, it becomes rootless. Tara is a national treasure and a massive tourist attraction for Co. Meath. It should be managed not simply as a hilltop site but rather as a cultural landscape, just has been the case with places like the Boyne Valley," he added.

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