The heatwave has been described as “critical” in the discovery of a henge, or circular enclosure in the UNESCO World Heritage Site close to Newgrange in county Meath.
The henge, which could measure up to 200 metres in diameter, is believed to have been built some 500 years after Newgrange which dates from 3,000 BC.
The drone that captured the image revealing its presence, belongs to historian and author Anthony Murphy who has been recording and writing about the Boyne Valley for many years.
He said “the weather is absolutely critical to the discovery of this monument. I have flown a drown over the Boyne Valley regularly and have never seen this.”
He said the bit of moisture left in the soil “lodges in the archaeological features a little bit more than it does in the surrounding soil and the crop that is growing out of the soil is greener in the archaeological features and drier outside of them.”
“So when that crop is harvested all surface traces of this monument will vanish and we may not see this monument again for 2 or 3 decades depending on when we get another prolonged dry spell like this.”
Archaeologist Dr Geraldine Stout, who has written about henges, said, “I believe Newgrange is just the centre of a much larger sacred landscape and I think there was a whole series of facilities built for the pilgrims coming to Newgrange in prehistory.”
“Generally we believe these henge monuments were built up to 500 years after the main use of Newgrange and in a lot of cases they actually enclose the area of monuments.”
In a statement today, the National Monuments Service said it will carry out “further technical work to help determine the nature of the site, but from the drone images visible on social media, it is a very significant find which fits within the knowledge of large prehistoric ritual enclosures and associated ritual landscapes as at Brú na Bóinne. The National Monuments Service would like to thank Anthony Murphy for reporting this discovery to us.”