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8 April 2014 • 4:06 pm Comments Off on The Beau Street Hoard: Not quite the end… conservation, outreach and further investigations

The Beau Street Hoard: Not quite the end… conservation, outreach and further investigations

replica of coin block before conservation
Hazel Gardiner, Metals Conservator, British Museum

The soil block after excavation of the hoard and prior to dismantling and return to the archaeologists who carried out the excavation.

For those who have been following the progress of the conservation of the Beau Street Hoard on the blog, I am delighted to announce that all the coins – around 17,500 of them – have now been cleaned to required identification standards, that is, to the point where the legend and significant features are readable. Conservator Julia Tubman carried out the bulk of this work on the c.17,500 coins contained within the hoard. Additional work has been carried out on a small number of these coins and conservation has also been carried out on c.400 coins that were initial finds from the outer edges of the hoard, before the hoard proper was unearthed. This last group of coins were in particularly poor condition and most required substantial chemical and manual cleaning. These coins were held in numbered paper envelopes, some of which corresponded to small find numbers allocated when the hoard was excavated.

Envelopes containing initial coin finds associated with the Beau Street Hoard

The soil block that held the hoard has now been dismantled and returned to the archaeologists who carried out the initial excavation for final sifting and checking for palaeoenvironmental remains: that is, material that might provide further contextual information about the coin hoard.

A washed but otherwise untreated coin from surface scatter coins showing the thick cuprite (copper oxide) layer obscuring the surface.

At the time of Julia’s last post, she reported that one of the coin clusters (bag 4), had been scanned. As with the other coins in the hoard, the clustered corroded coins retained the positions that they would have held in the bag in which they had been deposited. In this instance the bag shape was particularly well preserved. The initial scan was carried out at the British Museum by Martin Cooper of the Conservation Technologies Unit, National Museums Liverpool (NML). The scan data was used to create a 3D computer model, which was then 3D printed to make a replica of the coin bag using Selective Laser Sintering (SLS), a process that uses a laser to fuse particles of plastic or other material into the required three-dimensional form. A plaster cast was then made from the print and this was painted to resemble the original coin cluster, by conservators at NML.

The replica of bag 4

The replica has proved very popular among visitors to the Roman Baths and was shown at a Beau Street Hoard community consultation event run by staff at the Roman Baths earlier in 2013. Members of Bath Ethnic Minority Senior Citizens Association (BEMSCA) were among those who handled the replica. As a three-dimensional record of the original form of the coin bag, which of course no longer exists now that the coins have been conserved, the replica is an excellent supplement to the information gathered about the hoard, an invaluable means of allowing people to gain some sense of the physicality of (at least part) of the hoard.

Further exciting news is the forthcoming analysis of what appear to be animal skin remains from the bags used to store the coins. In one of Julia’s earlier posts she noted that traces of what appeared to be skin product, preserved by metal corrosion products, were found on the outside of each cluster of coins, suggesting that leather bags may have been used to house the coins. Professor Matthew Collins and colleagues at BioArCh (University of York), are hoping to extract collagen from the samples provided and to identify the species of animal skin used. Identification of the animal species will be made by peptide mass fingerprinting, an analytical technique for protein identification. We look forward to hearing the results of their investigations.

Possible skin product preserved by corrosion products from the coin beneath.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

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Filed under: Beau Street Hoard, Conservation, Beau Street Hoard, behind the scenes, Coins, conservation, hoard, research

27 September 2013 • 1:11 pm 2

A hoard from the dawn of Roman Britain

Coin from the hoard Eleanor Ghey, curator, British Museum

Sometimes as curators we are lucky enough to be brought the most amazing new finds that through careful study can offer a tantalising glimpse into the ancient past. One such discovery that sheds light on the earliest years of Roman Britain is now on display in the Citi Money Gallery.

Coins from the hoard on display.

In 2010 metal-detector user Jason Hemmings found – in a field in Dorset, southern England – what at first glance seemed to be just a handful of Roman and Iron Age coins. When he reported them to the Portable Antiquities Scheme it soon became apparent he had a hoard that can be closely linked to the years following the Roman conquest of AD 43.

It is a mixed sample of the different coins in use in Britain during these turbulent years. It contains worn silver Roman republican coins that had been in circulation in the Roman Empire for around 150 years and were also valued by local people as a source of silver. There were a few Iron Age staters, base silver coins issued by the native inhabitants of Dorset before the Roman conquest. Finally, and most significantly, there were copper alloy coins of the emperor Claudius issued between AD 41 and 50.

Coin of Emperor Claudius, Roman Imperial, AD 41-50

Official issues of the emperor Claudius are rare in Britain, although they were later copied in large numbers, probably to meet a shortage of supply. Two of the coins from this hoard are stamped with an official mark of approval found only in Rome and Britain. It is thought that these coins were produced in Rome in order to supply the invading army with useful currency whilst on campaign in Britain and may have even arrived with them. So they are likely to be close in date to the conquest of Britain in AD 43.

If this hoard belonged to a soldier, we can assume he was of lower rank, probably a legionary. At this time a legionary would have received an annual salary of 225 denarii. The hoard represents 4.25 denarii. A hoard of 34 Roman gold coins buried at Bredgar in Kent during the Claudian invasion – a vast amount of money more likely to have belonged to a high-ranking officer – is on display in Room 49. It is easier to imagine these coins from Dorset as the sort of sum carried by an individual: one of the lowest value Roman coins in the hoard would have bought two small sausages in ancient Pompeii!

Roman Republican coin, 100 BC

So how did these coins get into the ground in Dorset? It could be that we are seeing the contents of a purse lost by a Roman soldier as the famous Legio II Augusta advanced through the county in the years immediately following the conquest (under the command of the future emperor Vespasian). Alternatively, the coins could have found their way into local hands, which might explain the presence of local issues alongside Roman ones.

The question of how and why coin hoards were buried in the Roman period is currently being investigated in a new AHRC-funded research project by the British Museum and Leicester University. It will study the large number of hoards now known from Roman Britain (about 2,700) with a view to understanding the circumstances of their burial and what changing patterns of hoarding behaviour tell us about the economy and society of the time.

Coin of Emperor Tiberius, Roman Imperial, AD 14-37

For now, we can only speculate as to why these coins ended up where they did; while being grateful, of course, that some 2,000 years later we have the opportunity to try and tell their story.

The Money Gallery is supported by Citi

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Filed under: Archaeology, At the Museum, Money Gallery, Portable Antiquities and Treasure, Coins, hoard, Iron Age, Roman, Roman Britain

29 November 2012 • 4:32 pm 11

The Beau Street Hoard: the end of the excavation

Beau Street Hoard excavation Julia Tubman, conservator, British Museum

My last blog post recounted the excavation of bags 5 and 6 of the Beau Street hoard, which were the two smallest bags on the edge of the large hoard. In the months since, the deconstruction of the hoard has advanced considerably: as the excavation progressed I naturally became faster and more confident in removing the coins, and am pleased to announce the end of this stage of the project. The hoard was well organised, with the coins carefully sorted into bags according to denomination and level of debasement; specialists here at the British Museum now have a fascinating mystery to interpret.

The hoard towards the end of the excavation

In total eight bags were found in the hoard, which is two more than originally identified in the x-ray. Squeezed between the larger ‘bag 2’ and the centre of the hoard were two tiny bags, the coins of which are very similar to those contained within bag 2 – small radiate coins minted by Gallienus, Claudius Gothicus and Tetricus I.

Luckily, at the end of the excavation I was able to lift the large, central moneybag (known as bag ‘4’), whole, as I had removed all of the bags of coins surrounding it. The excellent preservation of this moneybag, which weighs nearly 11 kilograms, presents us with a very exciting opportunity. Already a laser scan of the bag has been undertaken to produce a rotating three-dimensional image, and a second scan will be taken before the end of the year which will be used to produce a facsimile to go on display in Bath. These scans provide us with a lasting document of the moneybag, which will now be de-constructed and the coins cleaned.

Moneybag 4

The block was x-rayed before the excavation of the moneybags, and so the base holding the coins had to be x-rayed after the removal of the last bag, to check that there were no ‘surprise’ bags beneath those already excavated. The x-ray showed only a few coins on the periphery of the base, and so we can move towards giving a final count for the number of coins in the hoard as a whole: at the moment it looks to be around half of the original estimate of 30,000.

Now the excavation is complete, I will be fully focused on getting all of the coins cleaned so that they can be identified by numismatists, who will begin to compile an ‘Emperor count’.

We knew at the beginning of the project that this would be a short excavation, and the perfect opportunity to experiment with time-lapse photography. Before I began the excavation, a camera was positioned on a workbench above the hoard, and programmed to take a photograph of the stationary block every 10 minutes. This short video neatly captures the deconstruction of the hoard, and makes for a fantastic record of the excavation.

On Friday 30 November, Stephen Clews from the Roman Baths, British Museum curators Richard Abdy and Eleanor Ghey, and I will be discussing the story of the Beau Street Hoard so far in a lecture at the British Museum.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

If you would like to leave a comment click on the title

Filed under: Beau Street Hoard, Conservation, Research, Coins, excavation, hoard, Roman coins

7 June 2012 • 8:49 am 5

The Beau Street Hoard: excavation progress

Julia Tubman, conservator, British Museum

As mentioned in previous blog posts, the Beau Street Hoard is not just one huge jumbled mass of coins, but actually at least six separate bags. My excavation plan is to remove these coins bag by bag, to preserve the groupings (which are potentially very significant), and give us a clearer view of the size and shape of each bag.

I had been concerned that the coins might have concreted together to such an extent that identifying separate bags would be very difficult during the excavation, but (fingers crossed!) thus far the removal of individual bags has progressed remarkably smoothly. I have managed to retrieve two whole bags of coins. I have numbered these bags five and six, and they are the two smallest bags at the northern end of the block in the x-ray (five being the smallest).

The block, after the removal of bags 5 and 6

We were excited to see that bag six almost exclusively contained denarii (the smaller coins with a high silver content discussed in Eleanor’s blog post last week), suggesting that the coins might have been bagged by denomination. Of the approximately 3,000 coins I excavated of this bag, I have cleaned around 1,000, and thus far the latest coins we have date to the third century AD.

There are actually a very small number of coins older than the third century contained within the bag: one coin was minted during Otho’s very short reign (AD 69), and an even older one, worn almost flat, minted at the end of the Roman Republic by Mark Antony (just prior to the battle of Actium in 31 BC).

This means that some of the coins were centuries old at the time of the final deposition of the hoard. As I’m cleaning the coins bag by bag in the order excavated, I haven’t yet got round to cleaning the coins kept in bag five, but thus far these all appear to be radiates.

A very worn coin minted by Mark Antony, circa 31 BC

As you can see in the photographs, it is quite easy to tell where one bag ends and another begins. The orientation of the coins themselves and the very bright blue corrosion helps a lot, but there are also other markers. The bags that held the coins would have been organic in nature (made from either an animal or plant product).My guess would be leather as they would have to be strong enough to hold large numbers of coins. Unfortunately, even organic material which has been treated and processed to form objects doesn’t always survive easily in Britain, which is why most of our surviving artefacts are made from stone, ceramic or metal. With this in mind, I knew that any piece of bag that might have survived would be in very poor condition, and I was prepared to look for scant pieces of evidence preserved in the corrosion generated by the coins.

Denarius bearing the emperor Septimius Severus, AD 193-211

Happily though, I think that I have found fragments of leather (see the light brown material loosely attached to the coins), exactly where I know the bags would have been. The leather is obviously very degraded, and as the fibre network has broken up, the leather has shrunken and split resulting in the flaky incoherent material we see today. I have taken some samples of this material, and hopefully my identification of this will be confirmed by a specialist soon.

The next stage of the excavation- the removal of bag 3

The next stage of the excavation- the removal of bag 2

After three weeks I now have a much better understanding of the size and shape of the hoard. There were no more coins beneath bags five and six, but the x-rays taken through the side suggest this is not the case throughout the rest of the block – we suspect there might be more bags of coins beneath the six already identified.

The area excavated thus far shows that the floor of the cist is obviously not even, but seems to have been dug in a rough pit-like way. As yet I have found no evidence of any kind of wooden box that might have held all of the bags, and as I have found pieces of tile pressed up against the coins, I actually doubt that there ever was.

Given the way in which the bags have been piled (I do not want to destabilise the central bags by removing their supports), and to get an idea of what the bags of coins in the middle of the block look like, I will now begin excavating ‘bag two’ at the southern end of the block. I’m sure there will be more exciting developments to report.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

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Filed under: Archaeology, Beau Street Hoard, Conservation, Coins, hoard, Roman baths, Romans

25 May 2012 • 1:57 pm 3

The Beau Street Hoard: what’s in the box?

Eleanor Ghey, project curator, British Museum

Hoards of Roman coins from later in the third century AD are the most common sort of coin hoards we see at the British Museum but the Beau Street Hoard is very unusual. When I saw the X-ray of the hoard I was very excited to see what looked like clearly separate bags of coins deposited in a group – normally coins are found in a pot or in a hole in the ground together in one lump. Here we have at least six (and probably more) groups of coins – several hoards in one! It was even more exciting to learn that it was going to be possible for my colleague Julia Tubman to isolate the groups.

It raises all sorts of questions. Do the bags contain the same sorts of coins or different ones? Do they each contain the same amount in Roman money or in weight of metal? Are they all coins that were circulating at the same date or are they deposits of coins from different time-periods gathered together at a later date for re-burial?

An X-radiograph of the soil block before conservation. © University of Southampton

An X-radiograph of the soil block before conservation taken at the Imaging Centre in the University of Southampton’s Department of Engineering Sciences. © University of Southampton

It is already possible to start to speculate about the contents of the hoard from the few coins that have been removed from the block (although it may still hold surprises). The coins are mostly of the denomination known as a ‘radiate’ (from the spiky crown the emperor wears on the obverse (front) of the coin).

A silver radiate of Gordian III from the hoard

This type of coin first appears in the early third century AD and at the time was of a value double that of the denarius (the main silver coin in the earlier years of the Roman Empire). Initially, like the denarius this was a silver coin. Gradually over time the silver content of the radiate was reduced, until (by the 270s AD) they were almost entirely base metal (copper alloy) and became smaller in size.

The first coins Julia removed from the block were large and silvery in appearance (once cleaned) and came mostly from the first half of the third century AD. The earliest coin was a denarius of the emperor Septimius Severus (ruled AD 193-211) and the latest were coins of the emperor Gallienus and his wife, Salonina, dated to the AD 260s. This would be fairly typical for the contents of a hoard buried in the AD 260s.

A silver denarius of Septimius Severus (AD 193-211) from the British Museum collection

However, when the hoard was first discovered, a sample of coins taken from another area of the block was quite different in nature. These were the smaller, more coppery radiates of the AD 270s (the most common type of coins we find in hoards from the 270s to 290s). This suggests that we may be dealing with bags containing different groups of coins, possibly gathered together at different times or sorted before burial.

Was this a secure store for bags of money that was added to gradually by one or more people over a fairly long period of time? It seems like an official store of money, organised into bags and purposely concealed in a place designed for that purpose. It was certainly a large amount of money (although we don’t have data for the later third century, pay scales for legionary soldiers in the AD 230s suggest they would have received about two and a half of these coins as a day’s wage) and it could have been looked after by an individual with authority.

It is rare to find hoards in Roman town centres. Perhaps it belonged to a local business in what was a busy town centre (deposited in a safe place in the way we leave money at the bank today). Why was it left for the archaeologists to find and not recovered by its owner?

Was there any connection with the nearby temple and sacred spring? We know that temples had treasuries; they may have periodically emptied out some of the coins thrown into the spring.

We are hoping that results from the archaeological excavation of the findspot will shed further light on this puzzle.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

If you would like to leave a comment click on the title

Filed under: Archaeology, Beau Street Hoard, Conservation, Coins, hoard, Roman baths, Romans

18 May 2012 • 3:41 pm 6

The Beau Street Hoard: excavating Roman treasure, one coin at a time

Julia Tubman, conservator, British Museum

In November 2007, during a routine archaeological excavation in advance of building work in Beau Street, Bath (a stone’s throw from the famous Roman Baths themselves), archaeologists came upon what was clearly a very large number of coins contained within a cist (a stone-lined box). Upon further excavation, they quickly came to realise they were looking at one of the largest coin hoards found in the UK, representing quite a tumultuous time in Roman Britain – about AD 270.

Some of the coins from the hoard during the initial excavation © Cotswold Archaeology

When groups of coins that appear to be over 300 years old are found, they must be reported to the local coroner (according to the Treasure Act 1996). The coins enter what we call the ‘Treasure Process’ where, if necessary for identification, they will be cleaned in preparation for their formal declaration as Treasure and the property of the Crown, or eventual valuation. Usually this occurs at the British Museum, or in the case of Welsh Treasure cases, the National Museum of Wales.

The hoard was lifted in a single soil block © Cotswold Archaeology

In order to preserve its shape and context, the archaeologists cut around the hoard and lifted it in a soil block. As a metals conservator at the British Museum, my job is to excavate the coins from the soil and clean them up. The initial excavation should take about six weeks and during that time I will be regularly adding to this blog with updates of my work as it progresses. Colleagues from curatorial departments and our science team who are involved with the project will also contribute as the hoard gradually reveals its story.

The hoard in its soil block when it arrived in the conservation lab at the British Museum

The coins are currently held together by soil and metallic corrosion. They are blue and green in colour indicating the corrosion of a copper metal, which would have been used as a base alloy for the coins. Interestingly, within this copper corrosion is actually a layer of silver that was plated over the copper during the manufacture of the coins.

The coins have also maintained the shape of the cist they were contained within, as the soil and corrosion has concreted together. Looking more closely, we can even see that there are groups of coins within the hoard; which is because this large hoard appears to be composed of six individual smaller hoards.

We had an idea that this could be the case because in December last year Dr. Mavrogordato, from the Imaging Centre in the University of Southampton’s Department of Engineering Sciences, kindly took x-rays of the block. The resulting images show what look to be ‘bags’ of coins. We don’t know whether the bags themselves have survived (they could have been made of an organic material such as textile or leather), but the corroded coins have kept the shape of their containers and I will be looking for evidence of them.

The cleaning process is fine and detailed work

As my job will involve excavating the hoard, knowing that there are individual bags of coins gives me a very good starting point as it means I can deconstruct the soil block bag by bag. It will be very interesting to see if the coins were bagged together for a particular reason; for example, if they were grouped by emperor or denomination.

I’ve cleaned a few loose coins already and, after stripping away the copper corrosion, I’ve found some very impressive silver surfaces (nicer than we had previously hoped!) Given the large number of coins in the soil block, I’m hoping to be able to clean as many coins as possible using chemicals such as formic acid, rather than by hand using a scalpel. I have 18 months to complete this project, so time is of the essence.

The hoard in May 2012 in the conservation lab, excavation underway.

Initial estimates put the number of coins at around 30,000. After having excavated the block a little since then, guesses about the maximum number of coins in the hoard have decreased and estimates vary between everyone looking at it. Readers of the blog are welcome to suggest their own figures – I say no more than 22,000 coins, what do you think?

Removing the tough shell of the copper corrosion layer is important not just to find shiny surfaces but also to find the detail on the coins needed for identification by my colleagues in the Coins and Medals department, Eleanor Ghey and Richard Abdy (who will be blogging about the significance of the find next week). At this early stage in the project, I’m only cleaning the coins so that they can be identified: I’m not cleaning them for display, by completely removing all the corrosion or soil; that would require more time.

Some of the coins after being cleaned

When looking at Roman coins, specialists will be hoping to identify features on the ‘obverse’ (side bearing the bust of an emperor or an important relative) and the ‘reverse’ (side bearing representations of deities, animals, and other important Roman symbols). The subjects depicted on Roman coins varied according to emperor and coins of more than one emperor could be in circulation at any given time. On both sides, revealing enough of the ‘legend’ (the writing around the edge of the coin) is important, especially where the figure in the centre is very corroded or worn. Eleanor and Richard will also be looking closely for any mint marks on the coins (usually on the reverse) which indicate where in the empire the coin was struck, so I’ll have to be very careful when cleaning to reveal as much detail as possible.

Coins identified thus far have shown a real mix of the many Roman emperors of the third century AD (it was such a politically unstable time that many of them only got to reign a few years): Septimius Severus (AD 193-211), Gordian III (AD 238-249), Philip I (AD 244-249), Decius (AD 249-251), Trebonianus Gallus (AD 251-253), Aemilian (AD 253), Valerian I (AD 253-260), Gallienus (AD 253-268) and Postumus (AD 260- 268).

The Roman Baths Museum hopes to purchase the hoard and eventually display it to the public. It’s fantastic to know where the hoard might ultimately end up, and I’m working closely with curator Stephen Clews at the Roman Baths.

Find out more about the Beau Street hoard and the Roman Baths Museum fund-raising campaign.

If you would like to leave a comment click on the title

Filed under: Archaeology, Beau Street Hoard, Conservation, Coins, hoard, Roman baths, Roman emperors, Romans

British Museum blog

The Beau Street Hoard: Not quite the end… conservation, outreach and further investigations

A hoard from the dawn of Roman Britain

The Beau Street Hoard: the end of the excavation

The Beau Street Hoard: excavation progress

The Beau Street Hoard: what’s in the box?

The Beau Street Hoard: excavating Roman treasure, one coin at a time

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The Beau Street Hoard: Not quite the end… conservation, outreach and further investigations

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