A long-running question over the authenticity of a coastal dolmen in Cork harbour has been resolved by archaeologist Michael Gibbons.
As the Irish Examiner reports, experts had been split over whether a tomb-like monument in the harbour’s inter-tidal zone was prehistoric or a more recent 19th-century “folly”.
Gibbons now says there is conclusive evidence that the Carraig á Mhaistin stone structure at Rostellan in Cork harbour is a megalithic dolmen.
Gibbons has also discovered a previously unrecognised cairn close to the dolmen, which would have been concealed by rising sea levels, and which he is reporting to the National Monuments Service.
The Carraig á Mhaistin dolmen at Rostellan is listed by some guides as Ireland’s only inter-tidal portal tomb.
In fact, there are two such inter-tidal tombs, Gibbons says.
The Rostellan dolmen with a 25-metre cairn extending from it below the estuary surface Photo: Michael Gibbons
He says that doubt about Carraig á Mhaistin’s age meant that it was not included in the State’s survey of megalithic tombs of Ireland conducted by Prof Ruaidhrí De Valera and Seán Ó Nualláin over 40 years ago.
“At that time, it was suggested that it could have a folly or type of ornamental structure commissioned by local gentry at the nearby Rostellan Castle estate, and dating from the 19th century,” Gibbons says.
A recent field trip by him to Rostellan has thrown up additional details, including discovery that the small chamber at the tomb stands at the western end of the cairn, which is 25 metres long and 4.5 metres wide.
This is significant as portal and court tombs “occasionally have intact long cairns which are both intended to provide structural support to the chamber itself, and to enhance visual presence in the landscape,”he says.
The cairn is “partially entombed in estuarine mud”, and it is probable that a great deal more of the structure is concealed below the surface, Gibbons says in a report he has written on the monument.
He notes it is not known for certain when the area was inundated by rising sea levels, but levels at this part of the Cork harbour shoreline are believed to have been stable for 2,000 years.
Gibbons says that the island's only other known inter-tidal portal tomb is at “the Lag” on the river Ilen, between Skibbereen and Baltimore in west Cork.
Portal tombs or dolmens were often known as “Diarmuid and Gráinne’s bed”, being associated in folklore as resting places for the fugitive couple who were pursued by Fionn MacCumhaill, Gráinne’s husband.
Gibbons also says that recent extreme weather has destroyed Sherkin island’s sole megalithic tomb on Slievemore townland, just three to four metres above the high water mark.
Read more in The Irish Examiner here
