Rathnadrinna Research Project

Combined geophysical survey results overlaid onto aerial photograph of Rathnadrinna, Cashel, Co. Tipperary


Project: Rathnadrinna Research Project, Cashel, Co. Tipperary.

Year: 2009-2014

Client: Richard O’Brien, funded by the Heritage Council and the Royal Irish Academy.

View of three banks and ditches overgrown by trees at Rathnadrinna.


Rathnadrinna Fort is a multivallate hilltop enclosure in the townland of Lalor’s-Lot outside Cashel, Co. Tipperary. It is one of the most impressive of several hilltop enclosures surrounding Cashel. In 2009, a project lead by Richard O’Brien began to carry out extensive investigations of the fort in order to gain further understanding of the history of the site. These included documentary research, aerial photographs, geophysical surveys and LiDAR. Earthsound were involved in the geophysical and LiDAR investigations of the enclosure and surrounding lands. The results of this research led up to a series of  archaeological excavations lasting three seasons from 2012-2014.


Heather, Tom and Mick using the Jalopy to collect earth resistance data inside the enclosure

Community Engagement: 

The Rathnadrinna Research project engaged members of the public throughout many of it’s stages. Locals and volunteers from all across the country and abroad were invited to join in the excavation team and be part of the project. Earthsound carried out a number of demonstrations of various geophysical techniques on site and some of the digging crew and visitors were able to get some hands on experience in operating the equipment.

Darren demonstrating the magnetometer cart

Loughmore National School children learning about metal detection

Geophysics: In 2009 we carried out high resolution magnetic susceptibility, magnetometry, earth resistance and ground penetrating radar surveys within Rathnadrinna Fort and in a surrounding field. The magnetic susceptibility and magnetometry data suggest an absence of occupation and industry inside Rathnadrinna, which could suggest by default a ceremonial or ritual role for the fort. Evidence for a (presumably prehistoric) field system which pre-dates the construction of Rathnadrinna was also found. Parts of the field system may be fossilised in the extant field boundaries of today and also hint towards a larger outer enclosure, also partly preserved in the modern field boundaries. The earth resistance survey identified 3 further circular enclosing ditches within Rathnadrinna fort and 1 possible ditch beyond the fort in Field 1, as well as a pit-circle at the centre of the fort. These suggest that Rathnadrinna may have been comprised of 6 concentric ditches (3 of which are extant), and a possible 7th ditch on the exterior. Combining this data with a potential larger outer enclosure comprised of extant outer field boundaries surrounding Rathnadrinna, suggests that possibly up to 8 circular enclosing features may have been identified.

3D display of combined geophysics interpretation on top of LIDAR image

In 2010 further geophysical surveys were carried out including high resolution magnetic susceptibility, magnetometry and earth resistance and electrical resistivity tomography surveys. A number of linear and curvilinear ditches and possible ditches or gullies have been detected across the survey area. Many of these appear to be associated with relict field boundaries. 19th century activity was also identified in the form of two possible structural remains which match features on the 1st edition OS map. The hilltop of Rathnadrinna is surrounded by an enclosure ditch measuring 250m in diameter. This single ditch enclosed the top of the hillside and has influenced the arcing nature of some of the modern field boundaries. A large number of circular ring-ditches and arcing ditches have also been detected outside the known fort. These appear to fall into two distinct types based on their size and morphology. Small ring-ditches measuring 15m-19m in diameter may represent foundation slot-trenches or drip gullies surrounding (unrecorded) wooden structures. Larger circular features measuring 40m in diameter, similar to the upstanding remains of the known satellite fort beside Rathnadrinna. These anomalies may therefore represent possible ploughed-out ringforts. The magnetic susceptibility data suggests an absence of burning activity – like inside the fort – perhaps discounting a settlement role for the ring-ditches and ringforts indicating that they might be burial or ritual monuments.

Electrical Resistivity Tomography (ERT) line running S-N across the monument including all banks and ditches.




Three seasons of excavations, beginning in June 2012 and the final season concluding in August of 2014, were directed by Richard O’Brien. Earthsound’s Heather Gimson was part of the digging crew as archaeological supervisor throughout all of the excavations. Additional Geophysical data was collected and demonstrations of the survey techniques were carried out by our staff on several occasions during the excavation seasons.

Heather and Meaghan planning stones in Ditch B, Season One 2012

Some of the crew, Season Two 2013









Cutting 1C at its busiest, Season Three 2014

Liam, Heather and Mick after finishing cutting 1C, Season Three 2014









Milestone – Earthsound survey all 26 Counties!

Following the completion of last weeks survey on the Black Pigs Dyke, Co. Monaghan, Earthsound have now reached a milestone: we’ve carried out a geophysical survey in every county in Ireland – it has taken 12 years but we got there! Our survey in Co. Monaghan (statistically the county with the least amount of planning applications and research projects) was the last one we needed for our collection!

If anyone wants some surveys done in Co. Tyrone in Northern Ireland, let us know – then we’ll have the full set of 32, north and south. After that, we’ll go for every offshore island – not that many are there?

© 2014 Earthsound Geophysics Ltd.

Black Pig’s Dyke, Co. Monaghan

Project: Black Pig’s Dyke Research Project, Co. Monaghan.

Location: Corrinary, Co. Monaghan.

Year: 2014

Client: Kilkenny Archaeology

Funding: Monaghan County Council

Electromagnetic Data showing the ‘Black Pig’s Dyke’

Aim: The Black Pig’s Dyke constitutes a series of earthwork fortifications located along the border of Northeast Connacht, Southwest Ulster and a small portion of Northwest Leinster throughout the counties of Cavan, Fermanagh, Leitrim, Longford, Monaghan and Roscommon with some possible links to earthworks in Counties Armagh, Donegal and Down. The earthworks comprise a series of banks and ditches with the banks being on average 9 metres wide and the ditches being on average 6 metres in depth, and having at one point contained a substantial palisade structure.The earthworks are considered to have an Iron Age provenance and were theorised by antiquarians to comprise an ancient boundary wall demarking the area of Ulster from the south, in particular as a defence against cattle raids.

Earthsound were commissioned by Kilkenny Archaeology as part of their involvement in the larger Black Pig’s Dyke Research Project, to investigate a portion of the Dyke located within the townland of Corrinary in County Monaghan, near the Cavan border. An Electromagnetic survey was executed across the site and two ditches (a substantial one to the north and a smaller one to the south) were discovered along with evidence for a possible burnt palisade.

Outcome: The geophysical surveys undertaken for this project have successfully identified the exact location and composition of the Black Pig’s Dyke within the survey area. Confirmation has been gained for the presence of two ditches, one on the internal (southern) edge of the dyke and a more extensive one on the external (northern) edge. Additional features included a possible palisade and ditch.

Heritage Week 2014 – Part 1 – Carry out your own Geophysical Survey!

Mayfield Lake, Wetlands and its Archaeological Heritage.

Earthsound director Dr James Bonsall gave a talk and guided walk on the archaeological heritage of Mayfield Lake and Clare Lake, Claremorris, as part of Heritage Week, in the Mayfield Community Building, in Claremorris on the 28th August.

The local audience joined in and told great stories of old place names and memories of fishing in Mayfield Lake. After the talk, James led the audience out to McMahon Park to let them carry out their own archaeological survey.


© 2014 Earthsound Geophysics Ltd.

Heritage Week 2014 – Part 2 – Meeting the Minister at Archaeofest

Earthsound’s Dr. James Bonsall attended the Institute of Archaeologists of Ireland Archaeofest event in Merrion Square, Dublin for the official launch of Heritage Week.

James encouraged visitors to carry out a geophysical survey in the park whilst explaining how instruments are used to detect buried archaeological features.

Among those that collected data were Minister for Arts, Heritage and the Gaeltacht, Heather Humphreys TD, who was very interested in the use of geophysical data on Irish infrastructure projects.

© 2014 Earthsound Geophysics Ltd.

We’re snapped by Google Streetview!

Well they had to catch up with us sometime: Earthsound have been immortalised on Google Street View during our research at Portumna Castle, Co. Galway. The survey was carried out in March 2011 and the Street View images are now available which show Heather and Darren with the MSP40 (Jalopy) Mobile Sensor Platform – you can almost see the expression on their faces. To see the image for yourself, have a look at http://goo.gl/maps/6fz0b. 1558500_10152396214585159_542142536044512053_n

© 2014 Earthsound Geophysics Ltd.

Commercial Archaeological Geophysics Seminar, University of Bradford

Earthsound director James Bonsall attended the first Commercial Archaeological Geophysics Seminar (#CAGS2014), at the University of Bradford, UK this week. Earthsound were the only Irish representatives at the event which brought together commercial practitioners, consultants, government stakeholders, curators and archaeologists to discuss the development of commercial geophysical surveys.

James presented the Irish perspective on commercial geophysical surveys (watch the video below) in his paper Tales from Across the Water: Analysing the Irish Experience of Geophysical Surveys, which discusses the limitations of magnetic scanning compared to detailed surveys. The paper was co-authored with Dr. Chris Gaffney and Prof. Ian Armit (University of Bradford) and Rónán Swan, NRA Head of Archaeology.

© 2014 Earthsound Geophysics Ltd.

Lecture at the Athy Heritage Centre-Museum

Town Walls and Castles – Recent Geophysical Discoveries in Athy.

Earthsound director Heather Gimson gave a lecture in the Athy Heritage Centre-Museum yesterday, County Kildare. Heather presented the results of our research on the Athy Town Walls and Castles which we’ve been working on for a number of years. This year we focused on using Ground Penetrating Radar and Electrical Resistivity Tomography over the Town Walls and Black Castle Tower which are located under a number of gardens and yards. The lecture was well attended and the audience included the Mayor of Athy.

© 2013 Earthsound Geophysics Ltd.

Lecture in Athy – ‘What is Archaeological Geophysics?’

Earthsound director Heather Gimson gave a lecture in the Athy Heritage Centre-Museum yesterday, County Kildare. Heather is working in Athy this week looking for evidence of the Town Walls and Castles using archaeological geophysical techniques. Heather explained the aims of the research and how geophysical surveys actually work. Many of those that attended the lecture are part of the project – the work currently involves surveying a number of peoples back gardens and yards to trace the medieval archaeology.

Heather will return to Athy in November to present the findings of the research.

© 2013 Earthsound Geophysics Ltd.

Earthsound’s Geophysicist Presents a New 5-part Radio Show

Earthsound’s Darren Regan has written, presented, produced and directed a new 5-part radio show, The Lie of the Land, for Claremorris Community Radio (CCR FM).

CCR FM won a Broadcasting Authority of Ireland award, supported by the Sound & Vision III scheme, which funds high quality programmes on Irish culture, heritage and experience. CCR FM approached Earthsound to develop the project which examines the history of Mayo, both geological and archaeological. Darren, who studied Applied Archaeology at IT Sligo has been working as a geophysicist for Earthsound Archaeological Geophysics since 2010 and drew on his extensive experience working on a variety of archaeological sites across Ireland to research and produce The Lie of the Land.

Mayo’s geological landscape tells a story of our land’s connection with place and cultures, which today lie oceans apart. The long and turbulent geological history of the West of Ireland, which stretches back hundreds of millions of years, contains tales of colliding continents and the fusing of North America with parts of this island.

Croagh Patrick, Co. Mayo

Darren takes listeners on a journey via reports from the prehistoric landscape around Croagh Patrick, to Céide Fields, Ballintubber Abbey, Iron Age cashels in Kilmovee and Bronze Age burial tombs in Irishtown.

Claremorris Community Radio’s new five-part series, The Lie of the Land, exposes the history of Mayo, both geological and archaeological. The show features interviews with archaeologists Richard Crumlish, Chris Read and Michael Gibbons, geologist Matthew Parkes, Fr. Frank Fahey, Earthsound directors James Bonsall and Heather Gimson and many more.

Produced, written, directed and presented by Darren Regan, this informative and enthralling series will start broadcasting on Saturday August 13th, at 2pm on Claremorris Community Radio. If you miss the show, don’t worry, The Lie of the Land will also be repeated on Fridays at 5pm.

© 2013 Earthsound Geophysics Ltd.