The National Roads Authority has revealed how it is excavating the controversial new national monument at Lismullen on the route of the €850 million M3 motorway.
Senior archaeologist with the National Roads Authority (NRA), Mary Deevy, admitted that so little evidence remains that "forensic archaeology" will be used to try and reveal exactly what it was used for.
The monument consists of two circular enclosures made of arcs of stake-holes and what appears to be an east-facing entrance; the diameter of the outer enclosure is 80 metres, the inner 16 metres.
Radio carbon dating has dated sample material to the middle Iron Age or around 400 BC.
The site occupies what will be part of the northbound lane of the motorway but it is currently home to four teams of archaeologists and their supervisors and a team of archivists.
The monument is being preserved by record, as directed by the Government and yesterday Ms Deevy, who gave a guided tour of the excavations to a small group of reporters, said "we don't downplay archaeology as we find it so exciting."
It appears the site was used for one phase of activity but whether this took place over a day, a year or decades is unclear and what that activity was also remains a mystery.
The archaeologists are taking regular samples of the soil for geo-chemical analysis.
"At this stage we don't know what it is going to tell us. We are really throwing all the scientific analysis at it because there is so little archaeology here. On a site like this you are essentially down to forensic archaeology.
"We are not finding materials you can hold in your hand, we are essentially looking for trace elements that can be analysed under a microscope chemically. Hopefully we will get results," she said.
Asked whether the radio carbon dating had tied the site into nearby Tara, Ms Deevy said: "There are so many individual sites on Tara that no matter what period this site was we would find some correlation. Before we had the date we had said it had similarities to a phase of Rath of the synods and that still holds to some extent."