Kilfinnane Motte – Adopt A Monument

Project: Kilfinnane Motte – Adopt A Monument

Location: Kilfinnane, Co. Limerick

Year: 2017

Client: Kilfinnane Community Council

Funding: The Heritage Council – Adopt A Monument

At the start of November Earthsound headed down to the village of Kilfinnane in Limerick. This quiet village hosts one of the most impressive monuments to be seen in the Irish landscape – a lofty motte, rising to 12m in height, surrounded by a series of imposing banks and ditches.

Standing atop the motte, sweeping views are given of the surrounding landscape – taking in Keale Mountain to the south, the Ballyhoura Hills to the southwest, the Galty Mountains to the east, and a rolling countryside to the north.

View looking south from on top of the monument – Galty Mountains on the left, Keale Mountain on the right and Ursula with the EM cart (Photo: C. Hogan)

This monument has been adopted by a community council and Tommy O’Sullivan acted as liaison for us. He, along with other enthusiastic locals, were able to fill us in with a great amount of detail of ‘The Moats’ recent background and older history.

Little is known about the history of the monument and there are very few other monuments recorded in its immediate vicinity. A standing stone is located in an adjacent field. The Kilfinnane Community Council has made great efforts to assemble of huge range of historical documents, local knowledge and folklore to create a greater understanding of the landscape – and the geophysical survey is another step towards this.

A broad survey was undertaken of the lands surrounding the motte. The site was investigated using an eight-probe magnetometry system and an electromagnetic instrument. The aim of the survey was to identify any associated anomalies, perhaps a bailey, or other unknown anomalies. The magnetometry covered the entirety of the survey area, whereas the EM was used to target the area adjacent to the banks and topographic features elsewhere.










Ursula surveying with the EM cart in front of the motte (Photo: C. Hogan)

Acknowledgements to the landowner Tom for allowing us access to his lands for the survey.

The survey was commissioned by Abarta Heritage, on behalf of the Kilfinnane Community Council, as part of the ‘Adopt A Monument’ Scheme being administered by the Heritage Council and Abarta Heritage.

Commissioning an Archaeological Geophysical Survey: what we need to know and what you need to know

Be it through Channel 4’s Time Team or through homegrown heritage documentaries, people’s exposure to, and understanding of what geophysical techniques can locate has greatly improved over the past few years. Many members of the general public will have an awareness of techniques such as Magnetometry and Ground Penetrating Radar and will have at least a cursory understanding of what they are and what they’re used for. We have become used to hearing about the wonderful knowledge that the ever-developing technology employed by geophysicists can offer us about our past and this can be of enormous benefit in terms of informing people outside of the field of geophysics. However, this can sometimes lead to a somewhat distorted understanding of the constraints and limitations associated with our techniques as well as the full extent of the information which we can realistically provide about a given site.

RTÉ One – Secrets of the Stones – Geophysics at Clonmacnoise

Here is an excerpt from RTÉ One's Secrets of the Stones TV show (2008) in which Earthsound participated. The clip shows us carrying out various geophysical surveys to find the outer ditch at the monastic site of Clonmacnoise, on the banks of the River Shannon. © RTÉ 2008, first broadcast 4th May 2009.

Posted by Earthsound Archaeological Geophysics on Wednesday, May 20, 2009


Our Geophysical Techniques cover a wide variety of technologies from the most commonly requested and well-known methods such as Magnetometry and Earth Resistance to methods which may be used more infrequently and for very specific site types of archaeology, such as Induced Polarisation for the location of wooden trackways within peatlands. Earthsound have the capacity to avail of a number of varied techniques and, when possible, can deploy more than one technique over a given site enabling us to yield the maximum amount of information available about the archaeology which lies beneath our feet. However….

Where are you looking?

The first thing we as geophysicists need to know before we can discuss what approach or methodology to undertake on your site is its exact size and location. This is important for a number of reasons. Firstly it allows us to provide you with the most appropriate technique to find what you’re looking for. The geological composition of the bedrock of the site can heavily influence the choice of technique. Although the geological make-up of the island of Ireland is fairly homogeneous, comprising mainly of carboniferous limestone, there are many regions where the geology may have an adverse impact on a technique that the client might request. A good example is the use of Magnetometry in the northern part of the island, where a large amount of volcanic and basalt geology can severely impede the ability of Magnetometry to locate the more subtle magnetic signatures emitted by archaeological remains.

Geological dyke found in magnetometry

The above image shows a Magnetometer survey containing a strongly magnetic geological dyke located throughout the middle of the survey area (the long arcing black-and-white line running top-left to bottom-right). As you can see, the strong signature given off by the geological feature obscures all of the other ambient magnetism as well as any anomalies of potential archaeological significance.

Another reason for needing to know the location of the proposed survey area(s) is for sheer practicality. Our Magnetometer array, for example, has a span of about 4m x 3m and has a large turning circle. This, added to the fact that it can be quite heavy, can mean that a promontory fort located on a sheer slope on the edge of a cliff may be a little bit beyond our capabilities!

As with everything, we are always eager to accommodate our clients and if we feel that one technique might not be amenable to the requirements of the site, we will suggest another, more appropriate one.

What is the land used for?

Another related question is the current and past land usage of the site. One of the main things we need to know prior to survey is whether or not it is possible to move our instruments unimpeded and ensure the collection of the best quality of data possible. For example, if the land is being used for tillage or silage, we would only be able to carry out our survey once the crop has been harvested or if it is in the very early stages of growth. In addition to this, land which is boggy or poached will present difficulties for our surveying equipment, alternative methodologies may be deployed in some instances. Similar issues apply to livestock so we would request that any areas which are to be surveyed be emptied of cattle and horses in particular.

Example of unsurveyable terrain

It is also especially important to know whether or not there has been a history of dumping or burning at a site. If a given area has historically been used to dispose of waste (such as cars) or has been used as a location for bonfires for example, this will have an extremely large impact on the efficacy of Magnetometry in that area and will mask any archaeological anomalies. In that instance, it may be that another technique could be employed. However, this of course depends on the site in question and we are always happy to discuss the possibilities.

What are you trying to find?

Last, but certainly not least, it is always useful to know what, if any, archaeological remains are expected. The size and type of archaeological remains being prospected for, especially for research, will influence the  instrumentation and sample intervals deployed. This is not only time-effective but cost-effective as it means the survey will detect the items of interest.

Having a full suite of geophysical techniques means that we can find most types of archaeology, however, some techniques will fair better at finding certain types of material whereas others will be inapplicable. In the case of stone and masonry remains (such as, for example, a castle) a magnetometer will not be able to detect the stone material of the structure. In this instance, where there is a known stone-built monument or structure we would probably advise Earth Resistance or perhaps an Electromagnetic Induction Survey for your particular needs.

Processed data and interpreted image of a stone-built leper hospital found in an Electromagnetic data set (white represents stone/high resistivity)

Another consideration when specifying a technique appropriate to the type of archaeology being sought is the size and morphology of the archaeological elements being investigated. Narrow slot trenches, pits, post holes, grave cuts, relict flowerbeds or other small dug features will be extremely difficult to find using standard sample intervals. Very high resolution surveys can be used to locate small elements, however in the case of very small features such as stake holes, neonatal burials or small pits the archaeology is so ephemeral that even a very high resolution survey may not locate any remains. All of these things are taken into consideration along with the terrain and type of geology and we will happily oblige in recommending the most effective technique or combination of techniques for the archaeology being investigated and in full consideration of the environment we are searching in.

If there is anything else that you are curious about in regards to what we can do for you, then please feel free to contact us.

Say Hello to the ‘Earthwalker’

Cian & James, walking the earth, with the Earthwalker

Our latest magnetometer array is the Earthwalker – the first in-house piece of equipment created by Earthsound Geophysics. The Earthwalker was designed, sourced and built by Earthsound’s Cian Hogan, with input and help from all staff.

Cian constructing the Earthwalker

Our regular multi-sensor magnetometer array uses a wheeled cart – however, due to increasing demand to undertake fieldwork in remote and challenging terrain, a more suitable and sturdy option was required. From uplands and rocky outcrops to dunefields and the inter-tidal zone, Earthsound’s new Earthwalker array allows us to carry out high-resolution GPS-acquired magnetometry no matter what the terrain.

The Earthwalker had its maiden survey at Knocknashee Hillfort, as part of the 2017 season of the Knocknashee Archaeology Project – and it was a great success! It took 8 people to transport our survey gear – 2 x GPS, 8 x ranging rods, food for the day (most important!), a metal detector, survey flags, 4 x magnetometers, an electronics box, and the Earthwalker array – to the top of the hill.

Heading up Knocknashee with the Earthwalker

Earthsound surveyors worked together to collect data over 9 Ha of data, developing a methodology and refining the array.The Earthwalker delivered the first large scale, high-resolution assessment of the Knocknashee hillfort interior.

…and here’s our regular (wheeled) magnetometer cart:

Vinegar Hill Battlefield Research Project

Project: Vinegar Hill Battlefield Research Project

Location: Vinegar Hill, Enniscorthy, Co. Wexford

Year: 2016-ongoing

Client: 1798 Interpretation Centre

Funding: Wexford County Council (2016, 2017)

Aim: Earthsound, together with Rubicon Heritage Services, IT Sligo and Cotswold Archaeology have carried out a series of geophysical and metal detecting surveys across the purported location of the 1798 Vinegar Hill Battlefield, with a view to confirming its location and systematically investigating elements of the battlefield. Earthsound have carried out high resolution Magnetometer, Earth Resistance, Electrical Resistivity Tomography and Metal Detection surveys.

Outcomes: The geophysical survey results are currently being written up for publication in a monograph and the investigation will be the subject of an upcoming documentary.

ERT probes set out at 1m intervals.

Dr James Bonsall explains the principles of ERT.

Knocknashee Archaeology Project

Project: The Knocknashee Archaeology Project

Location: Knocknashee, Lavagh, Tubbercurry, Co. Sligo

Year: 2016-ongoing

Client: Dr. Dirk Brandherm, Queen’s University Belfast

Funding: Royal Irish Academy Grant (2016, 2017)

Aim: The purpose of the geophysical surveys was to assess hut sites on the plateau of Knocknashee, a hillfort complex which also contains two Passage Tombs. In 2016 the entire hillfort interior – more than 20 ha in size – was assessed with Magnetic Susceptibility to identify zonations of activity. Specific clusters of huts and enclosures were further investigated with high resolution Magnetometry and Earth Resistance surveys. The 2017 survey used the ‘Earthwalker’ Magnetometer array across the southern half of the plateau and targeted Metal Detection surveys.

Social Media: Knocknashee Archaeology Project Facebook Page

Outcomes: The 2016 geophysical survey results are currently being written up for publication in a future edition of Emania. The results were used to target a series of excavations in 2017, under the direction of Dr. Dirk Brandherm.

Community Archaeology in Athy, Co. Kildare

Project: Athy Heritage Centre-Museum, Athy, Co. Kildare.

Year: 2013, 2014, 2015, 2016

Client: Athy Heritage Centre-Museum, funded by the Irish Walled Towns NetworkThe Heritage Council.

Aim: We’ve been carrying out a variety of projects in Athy since 2013. We’ve surveyed the Town Walls and Black Castle Tower using Ground Penetrating Radar and Electrical Resistivity Imaging and used Magnetometry and Electromagnetic Induction surveys at Woodstock Castle.

Community Engagement: We’ve given a number of lectures on our work in Athy at the Athy Heritage Centre-Museum, we’ve been visited by local schools and filmed for a short video that documented the surveys for the benefit of the local national school.

Outcomes: The 2013-2016 geophysical surveys have been used to aid the management of the Athy Town Walls and castles in a rapidly developing urban area. For more information on our work at Athy, see our collection of Blogs from Athy.

The Hellfire Club, Dublin

Magnetometry and a great view of Dublin City from Mountpelier Hill. Image: Abarta Heritage

Magnetometry and a great view of Dublin City from Mountpelier Hill. Image: Abarta Heritage

Project: The Hellfire Archaeology Project

Location: The Hellfire Club, Mountpelier Hill, Co. Dublin

Year: 2014

Client: The Hellfire Club Archaeology Project, on behalf of Abarta Heritage and South Dublin County Council

Aim: The purpose of the survey was to assess two Neolithic Passage Tombs  on top of Mountpelier Hill and the land surrounding the 18th Century Hellfire Club. The site was investigated with high resolution Magnetometer, Electromagnetic Induction and Earth Resistance Surveys, as well as LiDAR.

Community Engagement: 3 volunteers worked with Earthsound geophysicists over 3 days (volunteer labour contribution: €986)

Outcomes: The 2014 geophysical survey results were used to target a series of excavations in 2015 by the Hellfire Club Archaeology Project.

The geophysical survey was carried out as part of The Hellfire Archaeological Project in conjunction with Abarta Heritage. The site is located on top of Montpellier Hill in the Dublin Mountains which affords it a panoramic view of Dublin City and Bay. The summit of Monpellier Hill contains the remains of a hunting lodge built by the politician William Connolly in 1725. Adjacent to this is the probable remains of a prehistoric monument and it is thought that the lodge itself may have been constructed of stone robbed from these monuments.

According to folklore the roof had been blown down by a phantom from one of the tombs and Connolly had the roof reconstructed in stone.  Subsequent to Connolly’s death, the lodge lay in disuse for up to 10 years when it was leased by his widow Katherine to the Earl of Rosse, Richard Parsons. Parsons was a well known socialite and one of the ‘Young Bucks of Dublin’, a group of aristocrats who allegedly engaged in debauchery and possible Devil-worship, essentially what was to become the Hellfire Club. There are no direct accounts of Hellfire Club meetings occurring at Connolly’s Lodge on Montpellier Hill, however it is highly likely owing to its isolated location and association with Parsons.

Annacarty Remembered: RIC Barracks Survey

Magnetometry survey at the RIC Barracks

Magnetometry survey at the RIC Barracks

Project: Annacarty Remembered: RIC Barracks, Co. Tipperary.

Year: 2016

Client: Wolfhound Archaeology, funded by Tipperary County Council, Ireland 1916-2016 and The Heritage Council.

Aim: In June 2016, we carried out extensive Magnetometer, Electromagnetic Induction, Ground Penetrating RadarEarth Resistance Surveys and Metal Detection surveys at the RIC Barracks in Annacarty as part of a large commemoration event which was also filmed by RTE’s new television series John Creedon’s Epic East. The film crew were very interested in the geophysical survey and obtained some great drone and GoPro footage of our work.

Community Engagement: 1 volunteer worked with Earthsound geophysicists for 1 day (volunteer labour contribution: €164). The survey was filmed for RTE television and culminated in a large commemoration on the last day of survey, attended by more than 220 people, with Earthsound geophysicists on hand to explain the survey, it’s purpose and findings.

Outcomes: The 2016 geophysical survey culminated in a large commemoration ceremony (see below) attended by local school children and adults, the Army and many local politicians. The survey results will be integrated in to a management plan for the site.

The geophysical surveys were carried out as part of a research project managed by Wolfhound Archaeology, funded by Tipperary County Council, Ireland 1916-2016 and The Heritage Council. The research formed part of the Annacarty Remembers event, which commemorated the events of the War of Independence and Civil War.

The school children lead the procession up the hill towards the Barracks.

School children lead the procession up the hill towards the Barracks.

Annacarty Barracks, which was originally constructed as an RIC barracks in the early 19th Century, saw considerable action during the conflicts prior to the foundation of the Irish state.

In the spring of 1922, the truce had been signed and the barracks handed over to the volunteers. The children of Annacarty N.S. were marched up the hill to the barracks by the principal, Mr. Slattery and sang Amhrán na bhFiann for the volunteers as they raised the tri-colour.

The procession recreated the original event in 1922.

The procession recreated the original event in 1922.

On June 10th 2016, the event was recreated by more than 220 school children, local residents and visitors. The building bears the scars of these battles but is otherwise virtually untouched since it was burnt out after a short but violent siege in 1922 during the Civil War.

The Annacarty Remembers gathering walks up the hill to the Barracks.

The Annacarty Remembers gathering walking up the hill to the Barracks.

The surveys were led by Heather Gimson and supported by Dr James Bonsall, Darren Regan and Cian Hogan, who used various geophysical instruments to map additional structures around the barracks and carried out a detailed photogrammetry survey.

The magnetometer cart at the RIC Barracks

The magnetometer cart at rest by the RIC Barracks while John Creedon does some filming

Recording bullet holes in the wall. In the meantime, the 'Bone Detector' takes a snooze.

Recording bullet holes in the wall. In the meantime, the ‘Bone Detector’ takes a snooze.

Magnetometry and EMI carts

Magnetometry and EMI carts

GPR in action at the RIC Barracks

GPR in action at the RIC Barracks

We enjoyed wonderful hospitality from the people of Annacarty, who really welcomed us to their village. Particular thanks are due to Tom Tuohy, The Parish Shop & Tea Rooms and the Crossroads Pub (which kept us – and the dog – in great health with lots of ice creams and drinks.

Duncannon Fort, Co. Wexford

Project: Duncanon Fort, Co. Wexford

Location: Duncannon, Co. Wexford

Year: 2016

Client: Stafford-McLoughlin Archaeology

Funding: County Kildare Archaeological Society and the Kildare County Council Community Heritage Grant Scheme.

Aim: Earthsound Archaeological Geophysics were commissioned by Ms. C. McLoughlin of Stafford McLoughlin Archaeology on behalf of Wexford County Council to execute a geophysical survey in land adjacent to the Duncannon Bastion Fort as part of a conservation plan being carried with assistance from the Heritage Council, within the townland of Duncannon, Duncannon Village, County Wexford. The fort contains a church and a castle and it is believed that it may originally have been the site of a promontory fort owing to the derivation of the name meaning ‘Conan’s Fort’. Our main objectives were to determine the presence or absence of buildings and possibly grave plots associated with Duncannon Fort which are reputed to lie within the survey area and to investigate for any possible metallic artefacts which may be related to the usage of the fort. Earthsound carried out a comprehensive geophysical study of the site which included Magnetometry, Earth Resistance, Electromagnetic Induction and Metal Detection.

Outcomes: The geophysical surveys have revealed an extensive range of potential archaeological features which suggest the presence of multi-phase occupation. This activity appears to be concentrated in the northern field, while the central and southern fields have been heavily impacted by later activity such as the construction of a cinder block wall and soil deposition. Within the northern field a series of parallel and interconnecting boundaries have been detected. These could relate to agricultural activity or be associated with habitation. A number of circular possible enclosures were identified. These are unlikely to be contemporary with the fort but may indicate occupation on the site prior to the installation of military activity. The presence of numerous possible pits and four possible industrial anomalies as well as a series of possible structures down the western extent of the northern field suggests a large amount of habitation activity once existed on the outer edge of the fort. When the geophysical results are combined with the metal detection ‘hits’ a complicated picture emerges suggesting that the fields, as well as being used for habitation, may have seen warfare or at least the practicing of warfare.

NRA/TII Geophysical Guidance Document Now Online

The use of archaeological geophysics on national road schemes between 2001 and 2010 has been comprehensively reviewed as part of a National Roads Authority (NRA, now known as TII – Transport Infrastructure Ireland) archaeological research project funded through the NRA Fellowship Programme. The study, which was awarded funding in 2010, was carried out by James Bonsall, Dr Chris Gaffney and Professor Ian Armit from the University of Bradford in the UK. Earthsound Archaeological Geophysics acted as the university’s industrial partner in the research.

The research delivered a set of guidelines entitled Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010, which has been used by the NRA/TII to commission new geophysical surveys based on lessons learnt from the study. The document has recently been published online by the NRA/TII and other outlets.


The guidance document includes:

  • a review of previous geophysical surveys on NRA road schemes,
  • typical geophysical responses to a range of archaeological features, soils and geologies
  • a discussion of the limitations of various methods
  • advice on how to carry out surveys in ‘challenging’ conditions, landscapes and geologies
  • a Specification Key that assists non-geophysicists to determine the most appropriate geophysical technique(s) for a given study area or receiving environment.

Choice of geophysical survey methods for use on Irish road schemes. (Bonsall, J, Gaffney, C & Armit, I 2014. Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.)


Choice of geophysical survey methods for use on Irish road schemes. (Bonsall, J, Gaffney, C & Armit, I 2014. Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.)


Idealised performance of geophysical techniques upon principle Irish geologies. (Bonsall, J, Gaffney, C & Armit, I 2014. Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.)


Theoretical capability scores for idealised responses of archaeological features. (Bonsall, J, Gaffney, C & Armit, I 2014. Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.)


Historic methods of prospection from the 2001-2010 NRA Legacy Data. (Bonsall, J, Gaffney, C & Armit, I 2014. Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.)

Executive Summary of the Guidance Document

(Bonsall et al. 2014: 1)

This [guidance] document reviews Legacy Data generated from 10 years’ worth of road scheme activity in Ireland to determine how archaeological geophysical surveys could be carried out on national roads in the future. The geophysical surveys were carried out by several different contractors across a range of challenging field conditions, geologies, weather and seasons. The research is based upon the results of linear schemes but also has validity for wider approaches. The findings of this research are based upon the compilation of all terrestrial archaeological geophysical surveys carried out on behalf of the National Roads Authority (NRA), a review of the success or otherwise of those surveys in comparison with ground-observed excavations and in combination with experimental surveys that tested previously held assumptions or knowledge to determine best practice methods for the future.

The use and success of geophysical surveys in Ireland differ quite significantly from those in the UK, from where many of the methods of assessment were derived or adapted. Many of these differences can be attributed to geology. Ireland has a very high percentage of Carboniferous limestone geology, overlain mostly by tills and frequent occurrences of peat. These soils can reduce, to some extent, the effectiveness of magnetometer surveys; the most frequently used geophysical technique in Ireland. However, magnetometer data can be maximised in these cases by increasing the spatial resolution to produce effective results. An increase in spatial resolution is also effective generally, for enhancing the chances of identifying archaeological features by discriminating between archaeological and geological anomalies as well as increasing anomaly definition and visualisation of small and subtle archaeological features.

Outputs of the Research

Other outputs of the NRA Fellowship research have included:

  • A PhD for James Bonsall,  which was awarded in 2014.
  • James was selected as a finalist to present his research at the prestigious Transport Research Arena 2012 conference and was awarded the silver medal in the Environmental Pillar for his presentation.
  • A preliminary review of progress in Issue 6 of Seanda NRA Archaeology Magazine (published in December 2011) and a paper at the 2012 NRA National Archaeology Seminar. This paper, co-authored by James Bonsall, Dr Chris Gaffney and Professor Ian Armit, was published in the subsequent seminar proceedings in autumn 2013.
  • An online database from which NRA-commissioned geophysical reports. The NRA Archaeological Geophysical Survey Database was launched in April 2013 and an article about this important online resource was published in Issue 8 of Seanda.

Related publications

Bonsall, J  2011  ‘Ten years of archaeogeophysics’, Seanda, No. 6, 38–9.

Bonsall, J, Gaffney, C & Armit, I  2013  ‘Back and forth: paving the way forward by assessing 10 years of geophysical surveys on Irish road schemes’, in B Kelly, N Roycroft & M Stanley (eds), Futures and Pasts: archaeological science on Irish road schemes, 1–13. Archaeology and the National Roads Authority Monograph Series No. 10. National Roads Authority, Dublin.

Bonsall, J, Gaffney, C & Armit, I  2014  Preparing for the Future: a re-appraisal of archaeo-geophysical surveying on Irish National Road Schemes 2001-2010. Report by the Division of Archaeological, Geographical and Environmental Sciences, University of Bradford.

Bonsall, J, Sparrow, T, Gaffney, C, Armit, I & Swan, R  2013  ‘Underground, overground’Seanda, No. 8, 14–15.