Timeline — the story of South Wales’ longest dig

The pipeline snaking across the landscapeexcavation at Conkland Hill
The pipeline snaking across the landscape excavation at Conkland Hill

Timeline, a new book by Cotswold Archaeology, brings to a conclusion one of the longest (in terms of distance) digs ever to take place in Wales, if not the UK. The project known as the South Wales Gas Pipeline took place during the construction of a 317km gas pipeline that runs from Milford Haven via Felindre, skirting the edge of the Brecon Beacons National Park, through Herefordshire and on to Tirley in Gloucestershire. The post-excavation project, funded by National Grid, was undertaken by Cotswold Archaeology in collaboration with other archaeological organisations. The development itself was also a collaborative effort involving Network Archaeology, Cambrian Archaeological Projects, the various archaeological trusts, Groundwork Archaeology and the Rhead Group. In planning the route prior to construction great care was taken to avoid known sites of ecological and archaeological potential and importance.

Timeline cover
Timeline

Timeline is a synthesis of the results and covers over 10,000 years of human history, from at least the Mesolithic period to the beginnings of industrialisation. Pipelines by their very nature provide a thin slice across the contemporary landscape and present opportunities to explore past landscapes in areas not usually affected by commercial development. They often provide new and complementary information to existing knowledge that challenges our preconceptions of the past – where people lived and the routine of daily life. Ken Murphy (Dyfed Archaeological Trust) writes about Iron Age settlement in upland areas, Andrew David (formerly Historic England) and Prof Tim Darvill (Bournemouth University) report on Mesolithic and Neolithic activity (the latter including the discovery of a new henge monument), and Heather James (now retired) focusses on Early Medieval farming and diet. Seren Griffiths provides a radiocarbon chronology based on Bayesian analysis for many of the key sites, and James Rackham has written a synthesis of the past environment. Jonathan Hart sets the scene and provides discussion. The project produced large datasets and the book is a gateway to a significant online resource that can be explored at CA Archaeological Reports website (keyword search: South Wales Gas Pipeline).

Key discoveries include a new Late Neolithic henge monument at Vaynor farm – the subject of Mark Gridley’s visualization that depicts its reuse for ritual ceremony some 2500 years after its first construction.  A copper halberd blade with traces of its wooden haft was found during the excavation of a ring ditch at Trecastle (Powys) – a scary weapon (as depicted in the prehistoric rock art of Europe) that could have been used in ceremonial dance, ritual combat or simply for the poleaxing of cattle (see below).

Halberd and prehistoric art of Europe
Rock art figures and the halberd
site visit
Site visit

Other discoveries include a great many burnt mounds – enigmatic features of mostly Bronze Age date that may have been used to provide heated water for cleansing ceremonies. These features are a topic of much ‘heated’ debate for which the project has added some key sites and much new information, including an important set of radiocarbon dates.  Some of these features had troughs, including the preserved wooden example from Upper Neeston, Pembrokeshire. This find attracted much public interest and its lifting was witnessed by the then First Minster for Wales (the late Rt Hon Rhodri Morgan).

Not surprisingly, the route of the pipeline took in many rural areas that provided evidence for past lives and activities. The various features included crop processing ovens as well as evidence for woodland management activity including charcoal production. Charcoal was an important resource in the past and essential for small-scale iron production, as evidenced at Canaston Wood and depicted in Mark Gridley’s reconstruction.

Mark Gridley’s reconstruction
Mark Gridley’s reconstruction of the charcoal production

The publication of the book brings the project to a close and serves to promote the wealth of knowledge created during this remarkable episode in the exploration of the archaeology of Wales. Much of the information gathered during the project is available to access freely online. Copies of the book are available to buy at Oxbow.

Alistair Barclay

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Major new study shows ancient international trading routes between Exeter and Europe

Cutting-edge scientific techniques used to study ancient artefacts found in Exeter have revealed more about the ancient international trading routes between the city and Europe.

A five-year research project by a team of archaeologists led by Professor Stephen Rippon at the University of Exeter shows the links between merchants in Exeter and France, the Low Countries, Spain, Italy, Portugal, and the Mediterranean.

The artefacts are held by the Royal Albert Memorial Museum and Art Gallery in Exeter. The analysis has helped experts establish where various pottery vessels found in Exeter were made,

The analysis shows that in the Late Roman period people in Exeter traded with other ports along Europe’s Atlantic coast and in the Mediterranean. Fine quality table wares were imported from South West France, while vessels carrying olive oil, wine, and fish sauce arrived from North Africa.

The research shows pottery was imported from mainland Europe in the medieval period from Normandy, Brittany, and France’s South West coast, though some vessels also came from the Low Countries. In the 15th century pottery vessels were imported from even further afield including northern France, Spain, Portugal, and Italy.

The research project Exeter: A Place in Time, is a partnership between the University of Exeter, Cotswold Archaeology, Historic England, Exeter City Council, the Royal Albert Memorial Museum and Art Gallery, and the University of Reading. It was funded by the Arts and Humanities Research Council, Historic England and the University of Exeter.

Exeter began life as a fortress housing a Roman legion that, for a few years in the 60s AD became one of the most important supply bases in Britain as the Roman army tried to defeat a rebellion led by the British queen Boudica.

Map of medieval exeter

Exeter was a major town in both the Roman and medieval periods, with its fluctuating fortunes reflecting demand for local resources such as tin and silver, and its role in international trade.

When Britain ceased to be part of the Roman Empire in the early 5th century AD Exeter was abandoned for a few hundred years, but from the 10th century its fortunes revived. It became the fifth most productive mint in England, and a major centre for the tin trade. In the 16th and 17th centuries the region’s production of woollen cloth led to Exeter becoming the sixth wealthiest city in England.

Most of the pottery used by people living in Exeter was produced locally, although chemical analysis carried out as part of the project shows that vessels known as “Fortress Wares” were made from fine-quality potting clays found in the Teign Valley east of Dartmoor. This suggest that the Roman potters scouted quite widely around Exeter’s hinterland, searching for good quality material to work with.

Scientific analysis of another distinctive type of pottery found across the South West – South Western Black Burnished Ware – shows it was produced in the western parts of the Blackdown Hills, perhaps in the Hemyock area. In the Roman period clay from there was used to produce roofing tiles, and stone was quarried to make quern stones for grinding corn. Iron was also produced, showing how this now rural area was once a hive of industry.

Chemical analysis of animal bones from Exeter carried out as part of the project shows animals were moved seasonally during the Roman period, around a thousand years before the practice of taking livestock to graze on Dartmoor in the summer was recorded in written documents in the medieval period.

Professor Stephen Rippon of the University of Exeter said: “It is great to see this major study of Exeter’s emergence as a major city published. The application of modern scientific techniques has shown us how Exeter was at the centre of a network of trade routes that stretched across much of Europe.”

Neil Holbrook, Chief Executive of Cotswold Archaeology said: “As an archaeologist who worked in Exeter in the 1980s I was delighted to be a partner on this project. Together we have been able to achieve much more than any one of us could have done alone. The heroic efforts of Exeter City Council archaeologists working to salvage information ahead of redevelopment in the 1970s and 80s were not in vain – we can now see Exeter more clearly in its national and international context, in both the Roman and medieval periods. This project is an exemplar that can be followed by archaeologists and historians interested in other British historic towns and cities.”

Owen Cambridge, Principal Project Manager (Heritage) at Exeter City Council, said: “This is an important book which represents the culmination of five years of collaborative research. It results in a comprehensive re-evaluation of our understanding of how the City evolved, the influences and events which shaped its history, and ultimately how the past provides the context for the present, and for the future, of this unique City.”

Camila Hampshire, Museum Manager and Cultural Lead at the Royal Albert Memorial Museum and Art Gallery, said: “The project has brought out the potential of Exeter’s archaeology collection that have been stored at the RAMM for many years. The museum can now bring the new discoveries and the science behind them to a wider audience.”

The research is published in two books the first of which – Rippon, S. and Holbrook, N. (2021) Roman and Medieval Exeter and their Hinterlands: From Isca to Excester (edited by Stephen Rippon and Neil Holbrook) – is published by Oxbow books this month. A companion volume – Studies in the Roman and Medieval Archaeology of Exeter (also edited by Stephen Rippon and Neil Holbrook – will be published later in March. Both will be available as both an open access downloadable PDFs (from the Oxbow Books website) and in print form.

EAPIT books
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Roman military finds off Denmark Road, Gloucester

A Civil Service sports pitch on the site of a post-medieval quarry may seem like an unlikely place to discover an astounding assemblage of early Roman artefacts. However, Cotswold Archaeology did just that in autumn 2019 when we excavated a site off Denmark Road in Gloucester, ahead of its redevelopment by Redrow Homes South West.

Denmark Road site location
Site location within Gloucester

The excavation focused on an area just outside the eastern defences of the site of the Roman legionary fortress at Kingsholm. This military installation was established in the early years of the Roman conquest and abandoned c. AD 69. Later in the Roman period, the area was used as an inhumation cemetery. While most of the site had been severely damaged by extensive quarrying in the eighteenth and nineteenth centuries, some Roman features were visible. They included a large number of early Roman pits and a well. The well contained the skeleton of a dog, which was probably a closure deposit with religious or ritual significance. A disarticulated human skeleton was also found nearby, and is probably the remains of a Late Roman burial disturbed during post-medieval quarrying and redeposited in one of the quarry pits.  A ditch which was on the same alignment as the fortress defences, was traced across the site. This ditch appears to have acted as some sort of boundary, marking the limits of early Roman activity.

3D model of the Roman well under excavation

Buckle
A buckle from an Early Roman armoured cuirass known as a lorica segmentata

While these archaeological features give some insight into activity at the site, it is the artefactual assemblage of more than 140 objects which is particularly illuminating. As well as the brooches, bracelets and finger rings found on most Romano-British sites, this assemblage includes a huge number of objects of types used by both legionaries and auxiliary cavalry in the Roman army. They include an elaborate array of harness pendants, numerous fittings from the early Roman armoured cuirass known as lorica segmentata and even the foot of a piece of furniture in the shape of a lion’s paw.  More than 150 Roman coins were also recovered, the majority of which are copies of Claudian bronzes. These copies are thought to have been struck by the army to supplement military pay when there was a shortfall in the official coinage supply in the mid-1st century AD.

Lion's Leg and harness pendant from Denmark Road
Left: The foot of a piece of furniture possibly a food or water heater dating to the Early Roman period. Right: A phalera and harness pendant decorated with a human head dating to the 1st century AD
Claudian copy coin
A copy of a bronze coin of Claudius I known as a ‘Claudian copy’

Together, these artefacts suggest that the archaeological activity at Denmark Road is intimately associated with the early Roman army. Perhaps we are looking at the rubbish discarded by a vexillation of both legionaries and auxiliaries during the short time they were stationed at the nearby Kingsholm fortress….

Post-Excavation analysis on the site is currently underway, and the results will be published in due course. Watch this space for an update when the work is complete!

Philippa Walton

Denmark Road site
The site under excavation, facing west. The dark areas in the foreground are the remains of post-medieval quarry pits

Philippa Walton

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Geoarchaeology – Analysing Monolith Samples

‘Soil monolith samples’, such as these taken from a site in Yoxford, Suffolk, are a type of sample that we collect from features with changing accumulated deposits, such as alluvial channels (rivers) and ditch sections with significant sedimentation, or from buried soils, which were the old land surfaces of the site. These are taken vertically, using special tins or plastic guttering.

Taking monolith samples
Taking monolith samples
Examining a monolith sample in the lab
Examining a monolith sample in the lab

Back in the lab, our environmental team can then interpret and describe the sediments, to gain an understanding of the processes that led to the development of the site. Geoarchaeological assessment provides not only information about natural processes such as flooding and erosion, but also human exploitation of minerals, soils, and sediments; it can even offer information about preservation conditions. Gaining knowledge of the processes that have affected the formation and preservation of a site is key to helping us place archaeological features and finds in their correct environmental and temporal contexts.

By closely examining the sediments from monolith samples, we can assess their potential for further scientific study, including the analysis of pollen, diatoms and foraminifera (algae), soil micromorphology, and radiocarbon dating. The deposition of the sediments can also tell us how vegetation, agriculture and land management changed over time.

Agata Kowalska and Tom Brindle

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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 to order the past into a relative sequence, and occasionally certain objects such as coins provide a good level of precision within the historic period. However, if we have no artefacts or are dealing with time before the historic period, we have several clever scientific techniques in our armoury — one of which is radiocarbon dating.

Radiocarbon dating is a technique that was developed from the 1940s onwards and can be used to date anything that was once living (carbon-based life forms), or which was made from organic material. Material frequently found on archaeological sites suitable for radiocarbon dating includes the butchered remains of animals, objects made from bone, or food residues such as dried burnt stew, which is sometimes found lining the sides of cooking pots.

Radiocarbon (14C) is formed in the earth’s atmosphere and is absorbed by plants, where it enters the food chain – as part of the diet of animals and humans. When a living organism dies, they stop taking in carbon, of which there are two types: stable carbon (12C) and radioactive carbon (14C). The latter starts to decay after death, and by measuring the ratio between the two we are able to determine the age of the sample. This involves physics (to understand how carbon atoms decay), chemistry (the composition of the material), some clever maths (statistics) to calculate the date (its range, any possible errors etc.) and an archaeologist (the fun part) to interpret the result and what it means.

We use radiocarbon dating to assign a precise date to an event such as the burial of a person. However, in general radiocarbon provides us not with a single year but with a date range in which an event probably occurred.

Radiocarbon was used to date two otherwise undated human burials to the early Mesolithic

However, over the last 25 years new methods based on mathematical probability – known as Bayes’ Theorem have been used to develop programmes such as OxCal. Put simply, the probable date range of an event can be reduced if we are aware of other useful information. For instance, if we know from fieldwork the order in which a particular group of graves were dug in the past, this allows us to combine the basic radiocarbon dates with known archaeological information, allowing the production of more precise chronologies for a site. For example, we can model a site’s beginning (construction), its end, and its period of use.

We routinely use Bayesian modelling of radiocarbon dates as part of our analysis work when we publish the results of our excavations. Recent examples include work on the A477 St Clears to Red Roses road scheme, on the South Wales Gas Pipeline, where the technique enabled subtle chronological modelling of activity at a henge and within the area surrounding a Bronze Age barrow. Bayesian modelling was also used to provide a more precise chronology for a newly discovered Late Bronze Age ring work at Hill Barton in Devon.  

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

One recent development pioneered at the University of Bristol is the radiocarbon dating of absorbed fats (lipids) that are found in the walls of unglazed pottery vessels. This technique allows us to directly radiocarbon date residues left following the cooking and consumption of food. This technique is still relatively new but the implications for improving our understanding of the development and spread of styles of pottery are huge, not least because pottery is usually the most common type of artefact we find on excavation sites. This new technique will eventually become widespread, especially in areas of the UK with acidic geology, where other organic remains such as animal bone are typically poorly preserved.  

Increasingly, and with the application of Bayesian statistics, radiocarbon dating is not just about time but how we write the history of the past.

Alistair Barclay

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Washing away the dirt: the use of hydrogen peroxide on soil samples during environmental processing

Environmental remains, which include material such as animal bones, charred plant remains, charcoal, pollen, molluscs and insects, have the potential to give us key information about the sites we excavate. These remains provide vital information about things such as diet in the past, what a settlement’s economy may have been based on, what the local landscape surrounding a site may have looked like, and how this may have changed over time. While some of these pieces of evidence are often found by our archaeologists working in the field, particularly larger animal bones, remains such as burnt seeds, charcoal, snail shells and small animal bones, are so small that they can be easily missed during excavation.        

A lab technician pouring hydrogen peroxide to a sample tub

Our archaeologists therefore regularly take buckets of soil samples from features like pits, hearths, ovens and ditches, so that we can recover small environmental remains that would otherwise be lost. In order to find the material within the soil samples, the soil needs to be washed away so that we can get at the precious bits of evidence potentially hidden inside. However, it can be hard to get samples from sites with clay soils cleanly processed without damaging the delicate environmental remains.

Sample tub

One thing that helps is presoaking the samples with a mixture of water and hydrogen peroxide. The hydrogen peroxide works a treat, fizzing away and breaking down the bonding between the clay particles, while it converts from H2O2 to water and oxygen – the reaction gently loosens the bonding between the clay particles, so they reduce in size until they are small enough to go through the mesh on our wetsieves. We then use a flotation tank to wash the clayey sediment away, allowing us to float off the light environmental remains, with a residue of stones and small objects left over from the soil.

Without using hydrogen peroxide the process takes much longer: the clay samples can become plastic-like as the clay particles keep rebonding, and it is often hard to get them through the sieve without a lot of agitating of the sample by the processor – this agitation can damage the environmental material. leading to a loss of the important information it can contain.   

Sarah Wyles

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