Geophysical survey

Geophysics at Tintagel Castle: Non-invasive work ahead of the excavations

I am cheating on Day of Archaeology at little, as I am going to talk about work we at TigerGeo did in May, but that is being used to inform the very-much-happening-on-July-29th excavations at Tintagel Castle. We’ve been really excited to see the excavations progress over the last few weeks and can’t wait to get our hands on the reports and plans to go back to our own data with.

 

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Just getting the gear onto site was a challenge!

While there has been a lot of media attention about the excavations (see Sue’s excellent piece for the insider perspective), the geophysical surveys happened without much fanfare in May, in order to give us time to process the data and report it back to the dig team at CAU. We thought it might be interesting to have an insight into the work we did on site and the iterative process of interpreting, getting feedback and revisiting the data that we are engaged in. Most of the time, we don’t get such a great chance to see the excavations that follow our surveys so this is fantastic for us as we will be able to update our thinking and interpretations in detail.

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Magnetic Susceptibility readings being taken on the lower reaches of the southern terrace

So what did we get up to? The excavation team didn’t want to make such a drastic intervention on the site blind. They had target areas, based on what was already known or assumed about the site and asked us to look at them in more detail to allow them to better target their excavations. They were particularly interested in finding buildings from the post-roman period that had lain undisturbed by recent archaeologists, so they could look at them with fresh eyes and modern scientific methods. Any excavation is inherently destructive, and on sites as unique as Tintagel, it is important to minimise the impact of destructive research, so to help them do this we came up with a package of four complimentary methods:

  • Ground Penetrating Radar, which should be able to detect buried walls and surfaces
  • Earth Resistance Survey, which should detect the same things as the GPR, but using different properties of the material, giving us a ‘double chance’ to find them
  • Magnetic Susceptibility, a method that looks at how magnetisable a material is, telling us things about the presence of certain forms of iron. This can help distiguish between different activities taking place on site: we’d expect higher MS in areas of industry or settlement thanks to burning or heating, than we would in storage areas, for example
  • Terrestrial Laser Scanning, to produce highly detailed surface models to pin down the geophysical data but also very acurately located biulding platforms that had been recorded over the years by site archaeologists.
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This isn’t a photograph, it’s part of the point cloud generated by the laser scanner. You can see the team on the right trying to stay out of the scan!

A lot of fun was had on site getting ourselves and our equipment into the right places. Unlike the dig team, because we had to be quite mobile, with heavy gear, we needed to use a rope-access team to provide safety lines for us, so there were a lot of logistics to contend with around making sure we could cover the right areas. We were on site for a total of about 8 days, and really enjoyed talking to visitors to the site about what we were doing and why: people were particularly interested in the laser scanner and we’ve had to edit a lot of tourists (and seagulls) out of our point clouds!

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KC getting the scanner as far along the southern terrace as possible!

So what did we find out? The earth resistance and GPR surveys taken together confirmed the locations of some of the walls and floors that have subsequently been found in the trenches, and hinted that the archaeology on the southern terrace had a different character than that on the eastern area. The magnetic susceptibility data also suggested clear differences between the two areas, with low values on the eastern area and higher values with internal patterning on the southern terrace. This suggested to us that on the southern terrace people were living or working, using fire either for heat and cooking or for industrial purposes. We could also see come strong patches of enhancement that lay between what were thought to be buildings, so we suggested there may be one larger building here instead. The eastern area showed no settlement related enhancement. So were the buildings there perhaps storehouses? Many of the already excavated buildings in this area have been interpreted as stores rather than dwellings.

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Earth resistance underway (with ropes!) on the southern terrace

The laser scans were useful not only to us but to the excavation team as well as they will form the basis for the topographical data being collected about the site. We were able to use them to make important topographic corrections to our radar profiles, without which interpretation would have been very difficult!

GPR survey on the southern terrace: this is where one of the walls was found

GPR survey on the southern terrace: this is where one of the walls was found

So, what next? Well, our first and most exciting job is going to be to get all the plans and sections back in from the excavation team and see how they match up with our interpretation, especially of the radar: we were able to survey a larger area than could be excavated, so we can refine our interpretation based on the dig and better predict what other walls and floors lie on the southern terrace. Ideally, we’d like to come back and do even more radar and see if we can cover the entire southern terrace: this might give us the best chance of understanding the exciting structures there and their immediate context. We would also like to do more scanning to provide detailed topographic data for the entire islands. The Tintagel Research Project is set to continue, so watch this space….

You can see more photos from our work on facebook!

You wouldn't beleive how many of these we had to delete from the sky in our scans!

You wouldn’t beleive how many of these we had to delete from the sky in our scans!

 

Commercial geophysics for archaeology – a day at my desk

Cs mag survey around the long cairn

Cs vapour magnetic survey around the long cairn

We are a geophysical survey company working mostly in archaeology with some other shallow geophysical work alongside. This is ArchaeoPhysica’s second Day of Archaeology post, this time featuring mostly office work.

I’m Anne Roseveare, the Operations Manager, and I spend much of my time at a desk, make a few field visits and occasionally can be found in the workshop building and mending things. Unsurprisingly, my day involved quite a bit of time on the phone and emailing people about quote requests, ground conditions and schedules. Harvest dates are a hot topic at the moment as often fieldwork is held until the crops are cleared and we’re then wanted everywhere in a short time window. Our overall timetabling process has similarities to multi-dimensional tetris, or at least it feels like it.

We had fresh batches of data in from the previous couple of days’ fieldwork to process, visualise and prepare interim results to send to our archaeological clients. Kathryn’s been busy working through these, checking data quality and getting the data sets GIS-ready. I’ve also been working on the final stage of reporting for a multi-method geophysical survey on a deserted medieval settlement.

One of last week’s surveys was a couple of fields of magnetic data collected on a research basis next to a monument we surveyed using ERT (electrical resistance tomography) a few months ago. It’s not often you get to survey a neolithic long cairn and visit the excavation of the damaged part, so we were keen to see what (if anything) there was to see around it. Our work will inform the long term management plan for the monument.

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Our earlier ERT survey in progress

sloping slice across ERT profiles shows the internal structure

Sloping slice across ERT profiles showing some of the mound’s internal structure

some of the re-excavated internal structure in the damaged area - useful to compare with ERT

Some of the re-excavated internal structure in the damaged area – useful to compare with ERT results

talking through findings with one of the excavators

Talking through findings with one of the excavators

The rest of Friday’s workload was as usual completely commercially confidential – most of our work is development-related and is attached to planning applications (so no pictures from these).

I reviewed a WSI (Written Scope of Investigation) prepared by colleagues Daniel & Martin for a large project, updating the sections on soils & geologies. We often produce a WSI for large or complicated projects – sometimes it is required by the Local Authority Archaeologist or the client. It contains a summary of the purpose of the project and background information that will influence our geophysical work, including heritage and environmental information. Next comes the reasoning why our proposal is the most effective way forward and what the limitations are, followed by what the outputs from our work will be.

Another chunk of my time went into preparation for a forthcoming project, where there are multiple areas to survey and strict access arrangements as the site is sensitive. In this case, our project GIS will help us and the client to map out survey & no-go zones, schedule the different work areas (and re-schedule if needed as the work unfolds) as well as be the usual foundation for our reporting. We’ll be mapping visible signs of landscaping as the fieldwork goes on, too, to give our geophysical data local context.

Behind the scenes, out of sight of clients, there’s always other things happening. For example Martin was preparing a funding proposal to support a research project on a prehistoric mining site and there was unexciting but important maintenance of our internal project archive. Also, project Pegasus is moving along, with Martin & Benj on 3D design and construction (all will be revealed later this year). We usually have a development project on the go – it’s a case of fitting things round the commercial work.

I lost count how many mugs of tea and coffee we got through but this week’s Friday cake was carrot cake with particularly squishy icing – important fuel!

Geophysical surveys, Castles, Ice Cream and Sun

Hi from the team at ArchaeoPhysica!

We are an archaeological geophysics company based in Herefordshire, working nationwide and internationally. Much of the work we conduct is magnetometer survey, and we specialise in extra sensitive caesium vapour magnetometers, which we tow on a GPS guided sled array system behind a quad bike. This allows us to cover vast areas of land in a very efficient manner, compared to traditional walking magnetometer surveys (it’s also more fun!).

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The towed caesium vapour, GPS guided magnetometer sled

The day started extremely well, with the team situated down in Cornwall to conduct a commercial magnetometer survey over a mixture of pasture and just cropped fields (the harvest is very early this year) in advance of a proposed development. Luckily the weather was a warm 20oC so survey was extremely pleasant indeed. By lunchtime, the survey of two fields (approximately 5ha) was complete. To celebrate, the team headed to Launceston to see the castle, and have some fish and chips!

 A quick lunch break around Launceston Castle

A quick lunch break around Launceston Castle

Believe it or not, our next destination was Callestick Ice Cream Farm an hour away, to meet up with a new client who aims to create an archaeological community research project across many areas in Cornwall (and to taste the local produce). After a successful meeting, the team were back to work again to present the geophysics equipment and survey a 3ha field. The local farmer and his very interested grandchildren also came and visited the site, some budding future geophysicists no doubt!

Research links: Another satisfied customer

Research links: Another satisfied customer

Robert Fry, Martin Roseveare, Anne Roseveare, Sam Purvis & Dale Rouse

Web: www.archaeophysica.com
Twitter: @archaeophysica
Facebook https://www.facebook.com/archaeophysicaltd

A day of archaeological geomatics

Unmanned Aerial Vehicle in flight.

Unmanned Aerial Vehicle in flight.
Image © Callen Lenz

Well, firstly, I can’t believe it’s been a year since last time! Doesn’t time fly? What’s happened since then I hear you cry? I’m still the Geomatics Manager for Wessex Archaeology, responsible for GIS and Survey. The big news is my desk is now paper free and I’m trying to keep to a paperless work regime, essential seeing as most of my workspace is taken up with computer equipment, leaving no room for unnecessary clutter. In the photo you can see not only my laptop but the recently rebuilt GISBEAST machine with it’s quad cores, 64-bit OS and 12Gb RAM, tooled up with all the software I need to do what I do. (more…)

Discovering Dumfries and Galloway’s Past

Well, hello from a soggy south-west Scotland. I’m Giles, Development Officer for Discovering Dumfries and Galloway’s Past and I wanted to tell you on Day of Archaeology 2012 about the project and what we are going to be doing over the next week or so…

DDGP is an exciting new community archaeology project based in south-west, providing training in using geophysical survey to help volunteers record, understand and interpret the region’s fascinating archaeology. There’s going to be plenty of opportunity for local people right across the region to get involved in the surveys – it’s a great way to find out more about buried archaeology without having to excavate.

What is geophysics, and what can we find out using it?

Not all archaeology is about excavation – you may have come across ‘geofizz’ on TV’s Time Team where it’s often used to plan where to put the trenches in. Geophysics is a way of mapping buried archaeological deposits – be they ditches, pits or building material – without ever breaking the ground surface.

There are two main techniques for geophysical survey:

Glasgow University archaeologists undertaking resistivity survey

Resistivity: By passing a small electrical current into the ground, and measuring the amount of resistance that results, it is possible to locate buried remains of archaeological interest.

Resistance is related to the amount of moisture in the soil. Around buried walls, for example, the surrounding soil will often be dryer. The current cannot pass so easily through this dry soil, so stonework can often show up as areas of higher resistance. This technique is therefore ideal for locating building walls and foundations.

Glasgow University archaeologists undertaking magnetic survey

Magnetometry:  This technique detects extremely small variations in the earth’s magnetic field, caused when the ground has been disturbed by previous activity. Burning, for instance, will often leave a significant magnetic trace.

Magnetometry is excellent for locating ditches, pits, middens, hearths and kilns – and is great at covering large areas quite quickly.

The great thing about geophysical survey is that the results can be rapidly downloaded on site to a laptop, and even with minimum processing it is possible to define ‘anomalies’ which can represent buried archaeology. For volunteers on the project surveys this is great – they can see the fruits of their labours in the field. We are aiming to get these very quickly into reports which will be uploaded onto our website, to share them with as wide an audience as possible.

Our next survey
It’s all a bit hectic in the office today as we put the finishing touches to our programme for next week’s survey. We’ll be undertaken both magnetic and resistivity survey at the nationally important site of the Roman fort at Birrens. This continues work that the University of Glasgow have been concentrating on – looking in and around Roman military sites in Eastern Dumfriesshire.

Magnetic survey results around Bankhead Roman fort, Dalswinton

This has looked at fabulous sites around Lockerbie, such as the Roman fort at Dalswinton. As you can see this has added loads of detail (as you can see on the right) to both the inside of the fort of Bankhead and the surrounding area – which aerial photographs have shown to be really interesting.

At Birrens Roman fort, near Middlebie, we’ll be focusing on similar things. A group of 6 volunteers will be joining us for 3 days next week to carry out some resistivity survey on the interior – hopefully we’ll get detail of the street pattern, as well as an idea of how the buildings – both the barrack blocks and administrative headquarters of the fort – were laid out.

You can find out more about Birrens fort – known to the Romans as blatobulgium (literally the ‘flour sack’) here.

We’re having an Open Day on Saturday July 7th – it’ll be a great chance to show the public the results as well as an opportunity to show just how geophysics ‘works’ – including the amount of walking in straight lines that’s involved! The response has been fantastic locally – so here’s hoping for some sunshine!

I hope this has wet your apetite both for ‘geophysics’ and the project – please see our website to keep up to date with the latest – discoveringdgpast.wordpress.com.

The project is jointly funded by the Scottish Government and The European Community, Dumfries and Galloway Leader 2007-2013; The Crichton Foundation and The University of Glasgow.

Archaeo-Geophysics in the Netherlands

Hello! For me, the day of archaeology will be a day of interpreting geophysical data which I collected earlier. I’ll start off with a coffee and fire up my computer. I will have to spend the day behind my computer rummaging around with my GPR- and magnetometry-data. Looking through my eyelashes, trying different colourmaps, data-filters, studying other available information just to see if geophysics will reveal certain lines, shapes and anomalies in general.

Conducting geophysical surveys for a commercial firm in Holland is what I do. Officially educated as an geologist/geochemist, I spend a lot of years in the environmental engineering field (soil surveys, soil remediation), but the combination of geophysics & archaeology was always appealing to me. At our firm Saricon, we also look for UXO’s, but my main field of interest is the world of archaeology!

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The best laid plans…

Well, following on from my previous post, my Day of Archaeology turned out to be rather different than planned. This is certainly not an unusual occurrence; working in archaeological computing in a commercial environment, all manner of things can crop up and cause the most carefully planned day to head off in another direction altogether.

Firstly, my LiDAR data didn’t arrive so that bit went out of the window. And a whole bunch of meetings were convened, so a big chunk of the day was spent planning upcoming projects and working on management topics. I did end up doing a bit of survey support, preparing some survey instruments for the following weeks work and helping one of the Wessex Archaeology fieldwork teams with a GNSS problem they were having. I also devoted some time to preparing a submission for a metric survey project which will include some Terrestrial Laser Scanning (TLS) and some Polynomial Texture Mapping (PTM), a form of Reflectance Transformance Imaging (RTI). I also looked at the final specifications for another TLS project due to start fieldwork imminently. TLS is rapidly becoming the most efficient and cost effective means of capturing 3D metric data for recording and analysis of archaeological sites, structures and landscapes and one aspect of my job is managing such projects. I also currently do much of the processing, analysis and visualisation work on the resulting point clouds (and watch out for some videos of previous projects coming soon to the Wessex Archaeology Computing Blog).

A colour orthographic image of a castle, produced directly from Terrestrial Laser Scan data

A colour orthographic image of a castle, produced directly from Terrestrial Laser Scan data

But by far the best part of the day was spent doing one of my favourite activities: Systems design and development. I am currently building an integrated GIS & database application for managing and interpreting marine geophysics data. As with any good software application, it needs to effectively support the processes applied by the users, in this case the marine geophysics team. The data structure needs to be based around a solid and robust model of the information recorded; it needs to record not only the raw and interpreted data but the necessary Quality Assurance and metadata needed for analysis and reporting. I do enjoy this kind of work as it is creative and logical at the same time and to get it right, one needs to understand the detail and nuances of the processes being developed for, a good opportunity to find out more about different areas of archaeology (I have previously developed context recording systems for archaeological fieldwork, diver recording systems for marine archaeology and a variety of recording and analysis systems to support projects such as Environmental Impact Assessments and Conservation Management Plans).

My evening was indeed spent as planned finishing off a paper for publication. Whilst my main interest is in archaeological spatial technologies, I also have research interests in the application and development of data standards, thesauri and ontologies. My paper was based on how these various strands are coming together to support and arguably change the way in which archaeological theory is formulated, giving archaeologists the tools to discover information more easily and then develop more data driven theoretical assertions.

So a little bit different to what I had planned but I do hope still of interest to some.

Writing a press pack for the British Science Festival

I’ve spent most of today writing the press pack for the British Science Festival. Engagement with journalists is important. Journalists provide the opportunity for you to get your information out to a wider audience. The challenge is to take complex data and interpretations and find a way to present it to journalists in a way which is both accessible and allows them to weave a narrative which is interesting to their readers.

Here it is….  Apologies to those who do other archaeological prospection work: you may think it’s a bit biased towards aerial approaches. It is, but that’s the very issue for a press release.

This draft will be sent through to the University of Leeds press office prior to submission to the British Science Festival.

The Electromagnetic Spectrum. Re-used under a creative commons share-a-like licence from DART_Project.

The Electromagnetic Spectrum. Re-used under a creative commons share-a-like licence from DART_Project.

I’m sure I left it somewhere: discovering our heritage through scientific prospection

Anthony Beck – School of Computing, University of Leeds

A presentation for the British Science Festival in Session 56: Exploring new archaeological worlds, 12 September 2011.

Can you provide a brief introduction to the topic of your presentation?

Guidance: This should be more than an abstract or one-paragraph summary of your research. We would anticipate the summary of your presentation to be in the region of 1000 – 1500 words. Two to three sides is ideal. It is an opportunity to introduce the main findings of the work/research described in your presentation, as well as to include relevant background information and to fit your work within the wider context. It should contain specific information (e.g. data, number of people included in any studies, etc) that would enable a journalist to accurately write a story about your work, without them having to hunt around for details elsewhere. Due to time constraints journalists are rarely able to attend the talk itself, which is why press papers are so important – therefore the details you provide shouldn’t assume that the journalist will be attending your talk.

Summary/Abstract (174 words): Multi-spectral and hyper-spectral sensors offer immense potential as archaeological prospection tools. The sensors are sensitive to emitted or reflected radiation over different areas (wavelengths) of the electromagnetic spectrum. Their two major advantages are that they have the potential to detect archaeological sites and monuments (henceforth archaeological residues) that are undetectable in the visible wavelengths and that they may extend the window of opportunity for their detection. For example, localised crop stress and vigour variations, which underpin crop-mark formation, are sometimes better expressed in the near-infrared than in the visible. In addition, multi/hyper-spectral data collected from different platforms (aerial and satellite) under different conditions can be used to generate ancillary themes that aid interpretation (e.g. soil, geology and land-use layers). However, multi/hyper-spectral sensors are relatively expensive and require systematic surveys under ‘appropriate conditions’ in order to be successful. It is this latter point which is critical: there is a poor understanding of the spatial, environmental and seasonal contrast dynamics that determine an ‘appropriate condition’ and therefore whether features of archaeological interest can be detected.

Text (1423 words): Although there are many examples of upstanding architecture, the vast majority of archaeological residues are expressed on the ground surface or buried and essentially invisible to the human eye. However, traces can be identified via changes in chemical, physical and biological attributes (either directly or by proxy) through, for example, changes in phosphorous content, clusters of artefacts and cropmarks. In the UK, the practice of using remote sensing techniques for detecting archaeological sites and visualizing archaeological landscapes has traditionally been based on low altitude aerial photography using film emulsions sensitive at optical and sometimes near-infrared wavelengths. The underlying premise of remote sensing is that interpreters can extract information about objects and features by studying the measurements from a sensor system. Both oblique and vertical aerial photographs have been used extensively for archaeological reconnaissance and mapping all over the world. Early aerial photographers helped to refine the instruments and establish methods that are still in use today. O.G.S. Crawford in particular established methods of site classification and wrote about the effects of weather, season, soil moisture and crop type on photographic return. Today, these aerial approaches are accepted as a cost-effective, non-invasive technique for the reconnaissance and survey of monuments.

However, recording using traditional observer directed reconnaissance and aerial photography is not without its problems. The reliance on a small component of the electromagnetic spectrum raises a number of issues. The small spectral window can introduce a significant bias as only certain residues under specific conditions express contrasts in these wavelengths. The over-reliance on the visual component of the electromagnetic spectrum has had a significant impact on data capture. The collection technique and technology mitigate against using any other sensor (peripatetic surveys are directed by visual observation from a plane and collected using an optical system, a camera out of a window: this technique will never allow the detection of the multitude of archaeological residues whose contrast expression can not be seen by the human eye – i.e. is outside the optical).  This presentation will introduce multi and hyper-spectral remote sensing (including the important resolving characteristics of the sensors) and the nature of the archaeological problems to which they can be applied. This is followed with a brief description of the DART project: a UK research project designed to improve the understanding of the application and the factors underpinning archaeological detection.

The main advantage to multi and hyperspectral imaging is that more of the electromagnetic spectrum is sampled at potentially finer spectral granularity; hence, there is more information about the objects under study. The main disadvantages are cost and complexity.  Unfortunately the archaeological application of this technology is under-researched: there is little understanding of the physical, chemical, biological and environmental processes that determine whether archaeological residues will be identified in one or any sensor. Hence, knowledge of which techniques will detect which components of the archaeological domain and under what conditions is poorly understood. Most multi and hyperspectral analysts use spectral signatures to accurately identify different vegetation and geology types. Unfortunately archaeological sites do not exhibit spectral signatures that can be used for generic detection purposes. Archaeological sites and features are created by localised formation and deformation processes. For example, as a mud-brick built farmstead erodes, the silt, sand, clay, large clasts and organics in the mud-brick along with other anthropogenic debris are incorporated into the soil. This produces localised variations in soil particle size and structure. This impacts on drainage and changes localised crop stress and vigour responses, which in turn changes reflectance characteristics.

Multispectral sensors address some of these problems because they are able to ‘look’ simultaneously at a wide range of different wavelengths. Wavelengths in the near and short-wave infrared add important collateral information to the visual wavelengths and improve the ability to discriminate vegetation stress and soil, moisture and temperature variations than either the human eye or photographic film. Narrow band spectral imaging can often help to enhance or distinguish different features on the ground or provide information on their state of health or ambient conditions according to their particular absorption and reflectance properties or their spectral signature.

This increased sensitivity is crucial for contrast detection. For example, cropmarks are an instance of localised variations in vegetation stress or vigour correlated with subsurface archaeological features. Wavelengths outside the visible are also sensitive to changes in vegetation health. Theoretically, exploiting relevant areas of the electromagnetic spectrum at the appropriate degree of granularity will mean that crop stress or vigour relating to subsurface archaeological residues can be expressed  more clearly and also that it can be detected both earlier and later in the growing cycle. Therefore, the window of opportunity for detecting archaeological features can be dramatically extended by using wavelengths outside the visible. This increased sensitivity means that archaeological contrasts can also be detected in soils and crops that have been traditionally categorised as marginal or unresponsive to aerial archaeological prospection. This is a significant improvement over traditional techniques.

We can hypothesise that archaeological residues produce localised contrasts in the landscape matrix which can be detected using an appropriate sensor under appropriate conditions. However, little is known about how different archaeological residues contrast with their local environment, how these contrasts are expressed in the electromagnetic spectrum, or how environmental, and other localised factors such as soil or vegetation, impact on contrast magnitude (over space and time).   This requires an understanding of both the nature of the residues and the landscape matrix within which they exist.

The Detection of Archaeological residues using Remote Sensing Techniques (DART) project (www.comp.leeds.ac.uk/dart) will focus on analysing factors that influence archaeological residue contrast dynamics. DART aims to determine how different remote sensing technologies detect contrast caused by different underlying factors under dynamic environmental conditions. This understanding will allow the optimal deployment of the different sensors.  By combining the results from a battery of sensors, each optimally deployed when the archaeological residues have the greatest likelihood of being detected, the maximal knowledge of archaeological residues can be achieved.

DART will address the following research issues:

  • What are the factors that produce archaeological contrasts?
  • How do these contrast processes vary over space and time?
  • What causes these variations?
  • How can we best detect these contrasts (sensors and conditions)?

The key will be to understand how archaeological residues differ from, and dynamically interact with, the localised soils/sediments and vegetation/crop and how these differences can be detected. Archaeological residue interaction models will be developed and tested under a range of different environmental, seasonal and crop conditions. In-situ measurements will be taken using probes and sensors, and samples will be taken for laboratory analysis. Standard geotechnical tests will be conducted such as density, grain size distribution, organic content, magnetic susceptibility, dielectric permittivity, geochemistry, pH and conductivity. Permanent in-situ probes will measure temperature gradient, density and soil moisture variations through a soil profile. In addition, each site will be visited regularly for measuring earth resistance, soil colour, conductivity, dielectric permittivity, hand-held spectro-radiometry, GPR transects and ambient climatic data. Traditional aerial flyovers and bespoke hyperspectral surveys will be commissioned.

Remote sensing can provide an impressive picture of the archaeological landscape without the need for invasive or expensive survey methods. The true potential of multispectral remote sensing, including thermal imaging, is still not clear and needs to be evaluated to test responsiveness under a broad range of climatic and ground conditions. Further research is likely to produce sensors capable of resolving relatively small features such as post-holes and shallow pits. When used appropriately, remote sensing provides a basis for testing hypotheses of landscape evolution that may be further explored by ground survey, geophysical survey or excavation. Large-scale airborne and satellite surveys can provide the framework on which planning policy and excavation strategies can be established. In addition, computer enhancement and the increased spectral resolution of the digital data places less dependency on the time of year for revealing archaeological features.

Remote sensing is increasingly important to many areas of archaeological enquiry from prospection through to management. It is therefore essential that it is not applied inappropriately. The inappropriate application of a single sensor could produce minimal results or the dogmatic application of that sensor will have diminishing archaeological returns. The combination of different sensors with different characteristics can produce profound interpretative synergies. Multiple sensors should be evaluated on the basis of ‘fitness for purpose’. Fitness for purpose in this context refers to the cost/benefit returns of each sensor and should be based upon an understanding of the nature of the archaeological residues, the sensor characteristics and the environmental characteristics of the landscape

What is new and interesting about your work?

Guidance: This should clearly summarise the main conclusions of your work, the key findings. This helps journalists (and the British Science Association Press Office) quickly identify key outcomes and is an important section to fill out. I’d suggest 100-200 words for this section.

Text (338 words): Geophysical and Aerial survey have substantially increased our understanding of the nature and distribution of archaeology remains. However, there is variable understanding of the physical, chemical, biological and environmental factors which produce the archaeological contrasts that are detected by the sensor technologies. These factors vary geographically, seasonally and throughout the day, meaning that the ability to detect features changes over time and space. This is not yet well understood. The DART project is a three year AHRC/EPSRC funded project with 25 partners from a range of disciplines.

Detection techniques rely on the ability of a sensor to measure the contrast between an archaeological residue and its immediate surroundings or matrix. Detection is influenced by many factors – changes in precipitation, temperature, crop stress/type, soil type and structure, and land management techniques. DART will increase the foundational knowledge about the remote sensing of sub-surface archaeological remains. To determine contrast factors, samples and measurements are taken on and around different sub-surface archaeological features at different times of the day and year to ensure that a representative range of conditions is covered. Field measurements include geophysical and hyperspectral surveys, thermal profiling, soil moisture and spectral reflectance. Laboratory analysis of samples includes geochemistry and particle size. This will result in a comprehensive knowledgebase.

During analysis the key will be to understand the dynamic interaction between soils, vegetation and archaeological residues and how these affect detection with sensing devices. This requires understanding how the archaeology differs from, and dynamically interacts with, the localised soils and vegetation and how these differences can be detected.

DART is an Open Science project. Open science is the idea that scientific knowledge of all kinds should be openly shared as early as is practical in the discovery process. By scientific knowledge “of all kinds” we include journal articles, data, code, online software tools, questions, ideas, and speculations; anything which can be considered knowledge. The “as is practical” clause is included because very often there are other factors (legal, ethical, social, etc) that must be considered prior to opening access.

What is the key finding of the work/research described in your presentation?

Guidance: What is it that would make someone sit up and listen? One way to approach this question is to imagine that you are talking to a journalist about your work – what are the key pieces of information that you would want to convey? Please do fill this out. Even if there is no ‘new’ research in your presentation, what message do you wish to convey, or what new angle will you present? Remember that whilst the research may not be new to you, there is every possibility that the journalists won’t have heard it before. I’d suggest 100-200 words for this section.

Text (317 words): The DART project is producing foundational research which will ensure that heritage/archaeological curators and policy makers are prepared for the challenges of the 21st Century and beyond. Current landscape detection techniques can be either too small scale or biased. For example, traditional aerial survey is biased in that it is mainly responsive on well draining soils. This means that difficult environments, like clays and pasture, have not been targeted. It is also possible that after a century of flying, in different environmental conditions, a point of saturation has been reached: no previously unobserved features are being detected – this does not mean that there are no new archaeological residues to discover, rather that no more can be detected with that particular sensor configuration. The DART knowledgebase will allow more effective decision making and management.

This work is particularly timely given the advances made in precision agriculture remote sensing and the application of Unmanned Aerial Vehicles (UAVs). Precision agriculture approaches are being used to increase yield by regulating crop growth to ameliorate extreme and non-ideal conditions (the very conditions under which ’never before seen’ archaeological features are observed). Advances in precision agriculture have the potential to significantly reduce the overall impact of traditional aerial archaeological approaches. An understanding of the underlying processes and dynamics in key crops and soils will help policy makers understand the potential impact of these developments and so determine curation and land-management policies more effectively. This will underpin the development of a framework for improving the detection of archaeological features through the more complete understanding of soil change, species phenology and the impact of different stress conditions on detection.

As an alternative: we have managed to exploit the new technology during the driest spring in Cambridgeshire since 1910. Whilst we are still analysing the results, the hyperspectral images have the opportunity to revolutionise our understanding of the buried landscape particularly in the clay areas.

What is the relevance of your work to a general audience?

Guidance: Think about in what way(s) the work is relevant to the general population, why it’s important. I’d suggest including around 100-200 words for this section.

Text (153 words):   The DART project is all about improving the underlying knowledge about process so that more archaeology can be detected. This will lead to better information and knowledge (for the public, for industry and for managers), which will lead to better decision making and policy formation.

In addition the DART Project is an Open Science initiative. Where practicable all science objects (data, algorithms, illustrations etc.) will be made openly available. An open license means that the outputs can be reused in a broadly unfettered way (be that for research, teaching and learning, personal edification etc.). Initiatives like Open Science in conjunction with the internet and social media are changing the research landscape. Research is become ever more open and collaborative. Consumers of research are participating in a conversation, not listening to a lecture. This more sophisticated form of engagement can increase impact and engagement dramatically. This will significantly change the way universities ‘do business’.

Isola Sacra – Existing Features

So the survey at the Isola Sacra has been running for the last three years. The area comprises an artificial island between Portus and Ostia Antica with the line of the Via Flavia running from north to south. A number of questions are being directed at the area, in particular relating to the location of the ancient coastline in the Roman period, the division and make-up of the ancient landscape an the presence or absence of buildings, workshop zones, cemeteries and other sites.

One thing that has stemmed from the survey to date is the presence of ancient canals sub-dividing the area, a small example of which appears below.

More of the same being processed at the moment suggesting the continuation of similar features. The area is marked by broad geological features also, all relating to the prograding of the Tiber delta in antiquity. For more information see www.portusproject.org/ and http://www.portusproject.org/fieldwork2007-9/regionalsurvey/results.html and http://bsr.academia.edu/StephenKay/Papers/185232/The_role_of_Integrated_Geophysical_Survey_methods_in_the_assessment_of_archaeological_landscapes_the_case_of_Portus.

Day of data processing – geophysical survey results from Isola Sacra

A day of processing of data, starting with the latest results from the geophysical survey at Isola Sacra, near Fiumicino, Italy.

 

 

This image shows a member of the survey team last year surveying using a fluxgate gradiometer over the central part of the landscape, an area of floodplain between the course of the river Tiber and the small Fossa Traiana, which demarcates the Isola Sacra between Portus and Ostia Antica. So far some 120 hectares of data have been collected, and the latest stage of processing is under way. More to follow later.