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.

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.

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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.
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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.)

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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.)

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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.)

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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.)

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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.

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.

Aim: 

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.

 

 

Excavation:

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