18 July 2025 The Future is the Product of the Past

A Mysterious Partially Submerged Structure in Ireland is a Prehistoric Tomb, archaeologist says

New research has revealed that a mysterious structure found many years ago on the eastern shore of Cork Harbor in the Rostellan Woods, north of the small village of Rostellan in Southern Ireland is a prehistoric tomb.

Archaeologists had disagreed over whether Carraig á Mhaistin, which is located on the eastern side of Cork Harbour, was a prehistoric tomb or a 19th-century “folly,” but now, according to Connemara-based archaeologist Michael Gibbons, there is unambiguous proof that the structure is a megalithic dolmen.

A small chamber on the west side of an unknown cairn, a man-made stone stack marking a burial mound, measures 82 feet long by 15 feet wide. The cairn was previously concealed due to rising sea levels.

During the 18th century, Murrough O’Brien, 1st Marquess of Thomond, built “Siddons Tower,” a mock medieval tower on the former estate of Rostellan Castle. This led to the interpretation that the structure was another of the Marquess’s follies, which is partially submerged during the day by tidal changes in the harbor.

The monument was not included in the State’s survey of megalithic tombs in Ireland, which was conducted over 40 years ago by Professor Ruaidhr de Valera and Seán Nualláin.

Connemara-based archaeologist Michael Gibbons now says there is conclusive evidence the Carraig á Mhaistin stone structure at Rostellan on the eastern shore of Cork Harbour is a megalithic dolmen. Photo: Michael Gibbons

A new study by archaeologist, Michael Gibbons, has now concluded that the monument is a megalithic dolmen. Gibbons has also found a previously undiscovered cairn close to the dolmen and is reporting the discovery to the National Monuments Service.

Gibbons also discovered that the tomb’s small chamber is located at the western end of the cairn, which is 25m long and 4.5m wide.

According to Gibbons, monuments like this sometimes have intact long cairns intended to provide structural support to the chamber itself. The cairn is partially buried in the estuary mud, with most of the structure likely hidden beneath the surface.

It is unclear exactly when sea levels in the area rose, but they are believed to have been stable for the last 2,000 years.

The Carraig á Mhaistin dolmen is one of only three intertidal tombs in the nation, and there is only one other intertidal portal tomb on the island.

Portal tombs or dolmens were often referred to in Irish folklore as Diarmuid and Gráinne’s bed—a final resting place for the fugitive couple pursued by Gráinne’s husband Fionn mac Cumhaill.

Many of these structures were built near the coast; however, many have not survived due to movement in the Atlantic Ocean, including Sherkin Island’s sole megalithic tomb on Slievemore townland.

Cover Photo: The Carraig á Mhaistin stone structure at Rostellan on the eastern shore of Cork Harbour, Ireland. PHOTO: MICHAEL GIBBONS

Related Articles

Unprecedented 1800-year-old marble bathtub recovered in Turkey

23 April 2022

23 April 2022

The 1800-year-old marble bathtub, which was seized when it was about to be sold by historical artifact smugglers in Aydın’s...

Artificial intelligence is Detecting New Archaeological Sites in the Arabian desert

5 October 2024

5 October 2024

A team of researchers at Khalifa University in Abu Dhabi has developed a machine-learning algorithm to help them trawl vast...

Four-face ivory dice found at Keezhadi excavation site in India

18 February 2022

18 February 2022

The Tamil Nadu Archaeological department along with the Archaeological Survey of India has unearthed rectangular ivory dice,  in the excavation...

Could the Kerkenes Settlement be Gordion the Second?

1 August 2022

1 August 2022

Although the settlement on the Kerkenes mountain, located within the borders of Sorgun district of Yozgat, has been known and...

Early Roman Aqueduct Discovered in Turkey’s Aydın Province

27 May 2021

27 May 2021

In the Kuşadasi region of western Turkey’s Aydin, archaeologists and scholars unearthed an approximately 2,000-year-old ancient Roman aqueduct. Experts believe...

High-status Macedonian tomb discovered in ancient Aegae, Central Macedonia

2 April 2024

2 April 2024

In the ancient city of Aegae (present-day Vergina) in Imathia, Central Macedonia, during the construction of the sewerage network, tomb...

The 6,000-year-old settlement found in island of Corsica

2 May 2023

2 May 2023

Archaeologists in a French municipality recently excavated the slopes of Punta Campana (island of Corsica) in preparation for a construction...

A unique tomb decorated with amber was discovered near Petrozavodsk

26 August 2021

26 August 2021

According to a press release from the Petrozavodsk State University a unique tomb was discovered on the western shore of...

2,700-Year-Old Pre-Roman Iron Age necropolis Unearthed in Naples, Italy

8 May 2024

8 May 2024

An approximately 2,700-year-old Pre-Roman necropolis was discovered by archaeologists during excavations conducted in advance of a planned electric power plant...

Scientists recreate Stone Age cave lighting

17 June 2021

17 June 2021

For early hunter-gatherer societies that were lucky enough to live near caves, these natural underground homes provided ideal protection from...

A rare Byzantine gold coin discovered in Norway, probably brought from Constantinople

9 December 2023

9 December 2023

A metal detectorist exploring the mountains in the municipality of Vestre Slidre in southern Norway discovered a rare histamenon nomisma...

Human blood proteins were found in the red paint on a 1,000-year-old gold mask from Peru

27 October 2021

27 October 2021

Traces of human blood have been discovered in the red paint that decorated a gold mask found on the remains...

Ground-penetrating radars reveal hidden passages, described in Leonardo’s drawings

16 January 2025

16 January 2025

As part of a PhD thesis, an innovative technological investigation conducted by the Politecnico di Milano, in collaboration with the...

A rare medieval Christogram Tattoo from Ghazali, Sudan

22 October 2023

22 October 2023

A Polish-Sudanese research team investigating the medieval African monastery of Ghazali discovered a rare medieval religious tattoo in a tomb...

2,400-year-old unearthed flush toilet in China

18 February 2023

18 February 2023

According to a China Daily report, the lower parts of a flush toilet estimated to be 2,400 years old have...