British Museum blog

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 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.

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

Filed under: Archaeology, Beau Street Hoard, Conservation, , , ,

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

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

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, , , ,

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

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

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 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

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.

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

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, , , , ,

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This is Room 56, the Raymond and Beverly Sackler Gallery of Mesopotamia 6000–1500 BC. It's the next in our gallery series for #MuseumOfTheFuture. Between 6000 and 1550 BC, Mesopotamia, the land between the Tigris and Euphrates rivers (now Iraq, north-east Syria and part of south-east Turkey) witnessed crucial advancements in the development of human civilisation during the evolution from small agricultural settlements to large cities.
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