Remote Sensing and Archaelogy

Mon 17th Jun 2013

ArcLand’s two day conference K2U2 (from Known Knowns to Unknown Unknowns – remotely detecting the past) was held in Dublin City Council buildings on 9th& 10thMay 2013. It was attended by Niamh, Aisling, Maria and Conor.

Over twenty speakers primarily from Ireland, UK and Europe gave a range of papers in regard to remote sensing (Aerial Photography, Satellite Imagery, LiDAR, Geophysical survey i.e. all methods of non-invasive archaeological prospection) at various project locations throughout Europe.

Recurring in several of the papers was the fact that remote sensing data supplemented the knowledge of the number of known archaeological sites as recorded in National inventories of archaeology – in the case of Ireland on the SMR (Sites and Monuments Record) which has c 150,000 entries – www.archaeology.ie

In an Irish context it emerged that LiDAR survey is often conducted in regard to drainage work, site location studies etc. Dr Steve Harrison from UCD cited several such examples of low resolution LiDAR survey work which he acquired. On analysis these locations saw the presence of good archaeological potential.

The use of LiDAR in forestry was mentioned frequently to produce quantitive information about the timber crop. Additionally there is an ability to `strip out’ the tree layer’ and produce highly detailed ground models which can sometimes yield the presence of monuments which are otherwise hidden from above or even indiscernible from on the ground. In an Irish context the location of such sites often occurs on marginal and/or elevated land. Owing to the poorer quality of the land, less intensive agricultural activity has occurred there in the past thus increasing its potential to retain any of the archaeological resource. Jörg Bofinger, heritage manager of Baden-Württemberg in south western Germany spoke of this `virtual deforestation’ giving a tenfold increase in knowledge in his study area.

In Northern Ireland the Environmental Agency has started conducting LiDAR surveys at a small number of sites since 2008. Archaeologist Rory McNeary spoke about such a project in the Antrim Uplands which have yielded good results, the information from which will go to inform future planning and landscape management.

In conjunction with the conference an exhibition `Traces of the Past’ displayed fine examples of remotely sensed archaeological sites e.g.: The Hill of Tara, Skellig Michael and Bru na Boinne. This exhibition along with similar content to the Dublin conference is being toured throughout Europe on an on-going basis. More information on the exhibition is available at http://www.archaeolandscapes.eu/index.php/en/outreach/exhibitions/352-exhibition.html, where you can download a brochure that gives an overview of the exhibition.

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As a part of the ArcLand conference, The Discovery Programme ran an archaeological workshop on Saturday 11thMay in Phoenix Park. The aim of the workshop was to demonstrate different remote sensing techniques used by archaeologists to identify subsurface archaeological features in a non-invasive or non-destructive way.

The demonstration was carried out in a field next to the Cricket Grounds. A grid square was set out over an area which had no visible traces of historical ruins. Kevin Barton of NUI Galway explained the geophysical survey techniques using magnetic susceptibility, magnetic gradiometry and earth resistance, and used the grid as a guide for consistent measurements, taken at regular intervals. Using a variety of information including 1stedition OS maps, ortho-images, LiDAR, magnetometry data and resistance data they could identify the location of the star-shaped fort which was levelled in 1837.

Next, in a somewhat ‘MacGyver’ fashion, Dr. John Wells of the West Lothian Archaeological Trust explained how to easily create our own aerial kite photography kit using a keyring camera, some Velcro, a hook make from a coat hanger and a kite. Dr. Wells was championing aerial kite photography as a low-cost, environmentally friendly way of producing heritage/archaeological photography, which is accessible to everyone, including children. After some debate on weather conditions (having experienced the typical Irish summer with all four seasons in one day), Dr. Wells was eventually able to fly his kite with a point and shoot camera rig and took some aerial photos of the group, much to our delight.

To wrap up the morning session, there was a walk and talk about the history of the nearby Magazine Fort and Phoenix Park by licensed archaeologist Franc Myles who, despite the persistent rain, hail and wind, managed to hold everyone’s attention as he revealed its history and tales of the past.

Overall, it was a very engaging finale to the conference. It was a wonderful demonstration of the enthusiasm of ArcLand and The Discovery Programme to making people aware of remote sensing techniques in archaeology. As was iterated at several points in the conference, it is the practical hands on approach which can have a lasting effect on people’s understanding.