Mesolithic Cave Burial System Identified from Human Remains

The exciting results of early Mesolithic radiocarbon dates on human bones from the cave at Cannington Quarry are now published in the Proceedings of the University of Bristol Spelaeological Society, Volume 28 (3). Cotswold Archaeology (CA) previously reported the discovery of an entirely new Mesolithic cave burial site in Somerset, through our work on the human bone collection cared for by South West Heritage Trust – material which had been found in the 1960s.

Mesolithic burial sites in the UK are incredibly rare and the preliminary investigations by CA’s specialist in human remains, Sharon Clough, have significantly contributed to the knowledge of burial at this important time in Britain’s history, when it was being repopulated by people after the last Ice Age.  Sharon’s work owes a lot to the meticulous work of Philip Rahtz and his published account of the original discovery; it also highlights the importance of museum collections and archives for further research.  Additional work is planned on this collection, in collaboration with the South West Heritage Trust.  

For a copy of the Proceedings please follow this link to the UBSS website where it can be purchased for £12.50, or free to members of the Society. 12 months after publication PDF articles are available to download from the UBSS website at no charge.

If you have a press enquiry and require more information on these findings, please contact us at enquiries@cotswoldarchaeology.co.uk.

Right facial bones today compared with the original photograph before the calcareous deposit was removed

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The henge at Vaynor farm – found on the route of the SW gas pipeline and subjected to r

All in good time: radiocarbon dating

As archaeologists we are used to studying time and placing the archaeological material we excavate into its correct sequence. The identification of material allows us …
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SLAM scanning for tree-covered earthworks

The problem

Trees. They can frustrate even the most patient of surveyors. They block horizontal sight-lines for total stations, prevent vertical line-of-sight from your GPS to satellites, and have claimed many a 50m tape. You could commission a LiDAR (Light Detection and Ranging) flight to cover the area you want to survey, but this could be very costly and if the weather’s bad might not even get off the ground. However, there is one method of survey that loves to be surrounded by closely packed objects and can be operated by a weather-resistant geomatician: the SLAM scanner (which is also weather resistant).

Earthworks, to be scanned with SLAM scanner
Nice earthworks, shame about the trees

The solution

SLAM stands for Simultaneous Localisation and Mapping, meaning it can work out where it is and map the surrounding environment as you walk around. The most common SLAM scanner we use works by sending out 43,000 lasers per second to a range of 30m in a 360° x 270° arc in front of you and measures how far they travel before hitting something – imagine 43,000 30m tapes shooting out from where you are standing, every second, and reading each one instantly. The more objects the lasers can bounce off, the better able the scanner is to locate itself and the better the resulting mapping. So, rather counter-intuitively, the more obstructions, the better the survey.

The virtual lumberjack

The SLAM scanner, with weatherproof geomatician
The SLAM scanner, with weatherproof geomatician

The SLAM scanner produces a scaled ‘point cloud’ (see below for what this looks like) and can be georeferenced if you know the coordinates for a few of the points. If you’ve been scanning in a wooded area a lot of your points will be on trees or in the canopy above, so the next step is to remove the trees to show the lie of the land beneath. We can crop and slice the point cloud in a multitude of ways to reduce the number of redundant points and, to really fine tune it, we can pass it through various filters in the processing software to remove unwanted above-ground-level points. This gives us a DTM (Digital Terrain Model) that can be used to locate and interpret features which otherwise would be masked by trees and undergrowth. Below is an example from Dinas Powys Hillfort in the Vale of Glamorgan, which shows what the point cloud looks like from start to finish during processing, and how densely wooded the site is.

For anyone who wants to begin a deep dive into the complexities of SLAM scanning – the geoslam.com website is a good place to start.

Tom Weavill

For more examples of earthwork scanning check out our Sketchfab account.

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A person surveying a ditch with a GPS

Geomatics and Archaeology

The capture, processing, analysis and presentation of geospatial data Measured survey GPS At Cotswold Archaeology we use Leica Global Positioning System (GPS) instruments to capture spatial information for …
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Geomatics and Archaeology

The capture, processing, analysis and presentation of geospatial data

A person surveying a ditch with a GPS

Measured survey
GPS

GPSAt Cotswold Archaeology we use Leica Global Positioning System (GPS) instruments to capture spatial information for site plans and earthwork surveys. Digital measured survey complements hand-drawn and written records to form part of the primary site archive. It allows for accurate site plans to be produced and edited quickly, which is crucial for informing excavation strategy and providing a snapshot of site progress for managers, curators and clients.

Total Station

Total stationTotal Station survey produces results to the same degree of accuracy and precision usually associated with engineering specification and allows for survey in a built environment where satellite signals are obscured by tall buildings. The instruments are often deployed on burial sites where the recording of grave goods requires a greater level of accuracy than can be consistently achieved with a GPS instrument. Total Stations are also used in conjunction with other measured survey methods such as photogrammetry for historic building recording.

From site to office

The data captured on site is quality assured, processed, analysed and presented by our in-house Geomatics team. Our post-excavation team will then assign archaeological phases (e.g. late Bronze Age, early Iron Age etc.) to the recorded features using dating evidence provided by the finds recovered during the excavation, and careful stratigraphic analysis. Once assigned, the phases are exported from an access database and joined to the spatial data (the features) in GIS to generate phased plans and spatial distribution plots.

The phased plans are vital for providing a visual account of how the site has changed over time. The Geomatics team are able to provide individual plots of each phase of the site ready to be used by the Illustration team to produce report and publication figures.

Spatial analysis

Using GIS software we provide a number of valuable outputs for the interrogation and illustration of site data. These include spot date plans, contour maps and artefact distribution plots for spatial analysis.

You can view this article as an interactive story map that shows the use of GIS in action.

Check out these stories from our Geomatics team

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Structure-from-Motion: Photogrammetry at CA

At Cotswold Archaeology we use photogrammetry to create measured, textured 3D models at a wide range of scales, from recording small objects such as grave goods to entire landscapes using drone technology. This technique provides powerful visual results for our clients and for you, the public. Many of our models are uploaded to Sketchfab where anybody can take a virtual tour of the artefact or site and learn more about it by clicking on the interactive information points. Take a look at the Boxford Mosaic below.

But what is Photogrammetry…?

Photogrammetry, often referred to as Structure-from-Motion, is a technique that uses a series of overlapping two-dimensional photographs to reconstruct a three-dimensional object or structure. The images are processed using powerful software that identifies common points across hundreds of photographs, producing thousands of ‘control’ points (or, common points). These common points, along with known values from the camera, are used to compute the position of the camera in 3D space. This ‘sparse cloud’ of points is then processed to produce a dense cloud of points. You can see the difference between the sparse point cloud and the dense point cloud in these images of the Boxford mosaic.

The software then creates a 3D polygon mesh between the points, and provides texture by draping the 2D images over the model. As an example, here’s what the mesh looks like for Boxford!

3D polygon mesh of the Boxford mosaic
3D polygon mesh of the Boxford mosaic

We can use these models to produce accurate, measured, two-dimensional ‘ortho’ images, which have been used to great effect for recording burials and historic buildings. In the image below, you can see how the smaller plan of this trench provides a basic location for the deposits and structures (the purple, red, black, and blue shapes), while the annotated ortho image gives more meaningful information on the colour and texture of the deposits, and the stone and brick detail for the wall footings.

2d ortho photograph of an excavation area in Bristol

When we use this technique for recording historic buildings, we are able to provide good quality visual information on materials and condition for our inhouse specialists and for clients – just look at the example below.

For more of our photogrammetry models, head over to our Sketchfab page!

Rebecca Havard

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The capture, processing, analysis and presentation of geospatial data Measured survey GPS At Cotswold Archaeology we use Leica Global Positioning System (GPS) instruments to capture spatial information for …
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Is it a bird, is it a plane? Aerial Photography at CA

Not quite the angle we were after
Not quite the angle we were after…

When it comes to getting a bird’s eye view of an archaeological site, current-day archaeologists really do have all the toys. In decades gone by the most hi-tech equipment we were likely get our hands on was a beaten-up old theodolite (which required a master’s in geometry to use); and if you wanted aerial photography, you would have had to scale some scaffolding or head up a nearby building to get to whatever overhead vantage point you could. Strapping a camera to a kite or a balloon was even tried by the foolhardy (…ahem!).

These days we are spoilt for choice when it comes to options for getting those key images from above. The low-tech (and fairly cheap) option is an aerial mast. It doesn’t require a licence, or weeklong training, and at upwards of six metres tall it can certainly get you some excellent shots of your site. And if you have access to a sturdy vehicle, it’s possible to use fifteen-metre-plus camera masts!

The main components of the aerial mast are the telescopic mast itself, a motorised pan and tilt head with Bluetooth connection, a DSLR camera and a tablet to operate the camera from. The masts come in different varieties from monopods to tripods. For the safety conscious, guy ropes can be used to keep the whole thing secure. CA has been using camera masts for over 5-6 years on almost any site that deserves an elevated view with great results.

Aerial mast in use
Aerial mast in use
The Techie Bit…

The main components of the aerial mast are the telescopic mast itself, a motorised pan-and-tilt head with Bluetooth connection, a DSLR camera and a tablet to operate the camera from. The masts come in different types from monopods to tripods and, when required, guy ropes can be used to keep the whole thing secure. CA has been using aerial masts for many years on sites that deserve an elevated view, and with great results.

Site team photo, taken using an aerial mast

However, those with a head for heights, or who see themselves as the next Maverick, opt for the ultimate flying machine – the drone (or Unmanned Aerial Vehicle [UAV], for those who think this conjures visions of military war machines). A commercial pilot’s licence and a good amount of money are needed, but the end results are worth it.

The capability of these machines is truly awesome: the DJI Phantom 2, for example, can fly to an altitude of 11,000ft! However, UAVs are restricted to 400ft (122m) in the UK for safety reasons. There are an array of options to choose from, like the tiny ANAFI Parrot, which is 23cm long by 17cm wide, to the giant six-rotor drones. They have a range of cameras and other accessories that can be fitted to them for the job at hand, and they can even be fitted with a protective cage to shield them during use in hazardous locations.

CA has worked with drone contractors such as Aerial-cam, on almost every type of project, from excavations to earthwork surveys to historic building surveys. The capability they provide for recording archaeological sites at a detailed and contextual level make them an invaluable tool.

Photograph of an archaeological excavation site taken with a drone
Photograph of a Roman villa excavation site, taken with a drone

Not only can the cameras onboard provide static photos and film, but the imagery can be used to create photogrammetric models for analysing landscapes. To achieve this the site is flown in a grid pattern to capture overlapping vertical images across the site. The resulting photographic images are processed using specialist software to produce digital elevation models. But, more on that in tomorrow’s article!

Getting slightly different views of a site, by whatever means you choose, can be so rewarding for engaging people with a site. As archaeologists we often concentrate on recording at a micro level, but by using the aerial photography technology at our disposal we can see our sites in the wider world.

Jonathan Bennett

3D models of Clovelly Dykes hillfort, North Devon. Both available on SketchFab.

Check out these stories from our Geomatics team

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The capture, processing, analysis and presentation of geospatial data Measured survey GPS At Cotswold Archaeology we use Leica Global Positioning System (GPS) instruments to capture spatial information for …
Read More
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Further evidence for Iron Age occupation close to Ludgershall Castle

In March and April of 2021 Cotswold Archaeology undertook another excavation in the vicinity of Ludgershall Castle in Wiltshire, this time for Lovell and EDP, on behalf of Homes England, and Wiltshire Council. The results from this investigation indicate that occupation of the site occurred during the Middle Iron Age and Roman periods.

An aerial photograph showing CA's excavation of 2019 and 2021 in the vicinity of Ludgershall Castle
Middle Iron age grain storage pit during excavation
Middle Iron Age grain storage pit during excavation

The site, which is about 600m south-west of Ludgershall Castle, contained the remains of fourteen storage pits, further clusters of pits, some drip gullies and a trackway. The pits, which are believed to date to the Middle Iron Age, were probably grain storage pits and were found to contain pottery, animal bone, loom-weights and a copper object.  Some of the storage pits were up to 2.3m in depth and were capable of holding large amounts of grain, much larger then would be required for a single household. The number, size and scale of these pits suggests that a relatively large Middle Iron Age settlement once lay close to the site. The drip gullies may have been the remains of an Iron Age roundhouse, roughly 10m in diameter, but no dating evidence was recovered directly from these. The drip gullies were truncated by the two parallel ditches, roughly 5m apart, from a later trackway  that crossed the site during the Roman period.

Remains of possible bowl from Roman trackway
Remains of possible bowl from Roman trackway

A previous investigation by Cotswold Archaeology in November 2019 at Castle Farm revealed a Late Iron Age defensive ditch just west of the medieval outer earthworks of Ludgershall Castle. This was the first direct evidence found to indicate that Ludgershall Castle had originated as a prehistoric hillfort or defended settlement. The ‘hillfort hypothesis’ had been suggested earlier, as Ludgershall occupied an unfilled ‘gap’ in the general distribution of hillforts in this part of the country, and from the presence of ‘Celtic’ field systems visible on aerial photographs of the fields around Ludgershall. While not an especially prominent location for a hillfort, the village does occupy a low plateau which may have been attractive for early settlement.

Detailed plans of CA's excavations at Ludgershall Castle

The evidence from both of our recent excavations supports the hypothesis that there was an Iron Age hillfort and/or large settlement at Ludgershall, and that Iron Age occupation in this part of Wiltshire was more complex than previously thought.

Craig Jones & Ray Kennedy

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