Wednesday, June 8, 2016

Medieval metal working at Berkeley

One focus of the current excavations in the trench is the uncovering of 15th century buildings at the west end of the trench. These buildings show little evidence of domestic use with their assemblages devoid of the usual cooking pots and other domestic items. They have instead been suggested as industrial buildings used for the working of metal, in other words a possible late medieval smith.
This appears to fit with a previous interpretation of the site being used for metal working. Back in 2009 a large rectilinear building (see figure 1) was uncovered that dated to the 16th century. After consideration it was suggested that due to the lack of domestic assemblages this building was a series of separate workshops. Previous students studying Archaeological Science, analysed the soil material surrounding a stone hearth found inside the building and found evidence of copper, lead and zinc among other metals.
Fig. 1: Rectangular workshops
Evidence of zinc found on the site along with copper resulted in the possible conclusion that the workshops were working with brass, which is an alloy of copper and zinc. Brass is desired for being a versatile material that can be cast into moulds or sheets, which can then be hammered into shape (Victoria and Albert Museum and webmaster, 2012). However, creating brass was more difficult as zinc turns into a gas at the same temperature needed to melt the copper (Ward, 2008). The workshops at Berkeley were more likely used for working with the alloyed brass rather than smelting the zinc and copper to produce the brass. There is also a possibility that bronze was being worked, suggested from the evidence of copper and lead residue in the soil around the hearth. While it would also need the addition of tin, bronze is a strong and durable metal but can also be moulded and can be used to capture the fine detail and decoration (Victoria and Albert Museum and webmaster, 2012).

The hearth (figure 2) was located in the far room within the building and had two distinct phases. The second phase (figure 3) was comprised of a layer of large stones arranged to form a small square, which had cracked due to the intense heat needed to work with the metals. The stones underneath this layer made up the original first phase of the hearth (figure 4) and consisted of smaller stones tightly packed again forming a small square. When these were finally lifted the clay beneath showed clear evidence of prolonged and intense burning at high temperatures.

Fig. 2: View of the hearth within the building.


The items that were being produced on site are unknown, however other sites have provided clues into the types of objects made by medieval blacksmiths. Items such as; weapons, repairs made to armour, iron workings but also more delicate items such as jewellery (Siteseen, 2014).

Fig. 3: Second phase of the hearth


The discovery of the medieval and post-medieval workshops on the site is not the first evidence of metal working at Berkeley. The team have identified evidence of Saxon lead working and Roman iron and copper workings possibly suggesting the site was an important metal working site through the ages, although at present we now very little about this. Hopefully next year more detail about metal working at Berkeley during the Roman period will be revealed as the feature producing the iron slag has only just begun being excavated.

Fig. 4: first phase of the hearth.


Bibliography:
Ward, G. (2008) The grove encyclopedia of materials & techniques in art: One-Volume format, New York, NY: Oxford University Press.
Victoria and Albert Museum and webmaster, D. M. (2012) 'Brass - Victoria and Albert Museum', available at http://www.vam.ac.uk/page/b/brass/, accessed 8 June 2016.
Siteseen (2014) 'Medieval blacksmith', available at http://www.medieval-life-and-times.info/medieval-life/medieval-blacksmith.htm, accessed 7 June 2016.

- Bethany Holland.

Tuesday, June 7, 2016

Geophysical Survey: How Does It Work?

Over the last few weeks our students (see fig.1) have been undertaking geophysical surveys of the castle grounds under field technician Dr. Philip Rowe using Ground Penetrating Radar. GPR is a non-invasive technique which was selected to gain access to the areas of Berkeley Castle which cannot be excavated.
Fig. 1Students using GPR equipment.
High frequency radio waves are used by the GPR to detect subsurface features such as walls, buildings and ditches. The GPR system consists of an antenna with wheels, an interface display, a battery and a radar control unit (see fig. 2). The GPR detects buried features by emitting electromagnetic waves from the antenna. The transmitted waves bounce off buried objects, causing them to be reflected back to the GPR (see fig. 3), where the control unit transmits the data from the antenna to the user interface display where it can be viewed. It is commonly thought that GPR allows you to see through the ground like an X-ray. This is a common misconception – in reality GPR data can be difficult to interpret and only suggests the location of potential archaeological structures, where electromagnetic waves are being reflected off a buried feature. An example of the data received through GPR surveys can be seen in fig. 4 – potential structures are seen in the data as curves (these are indicated by arrows). The vertical axis represents the depth of the features – the deeper they are, the older they are. The horizontal axis shows where the features are in space.
Figure 2. An labelled digram of a GPR. 
Figure 3. The basic principles of GPR. 
Figure 4. Example of the data which results from GPR survey.
GPR can be heavily affected by soil type and weather, as moisture in the soil reduces the accuracy of the data – luckily we’ve had lovely weather the last few weeks. GPR has been especially useful in areas such as the inner keep of the castle and the carpark, while are covered in stone or tarmac and can therefore not be excavated. See fig. 5 for a guide to where GPR surveys have been carried out around the castle.
Figure 5. Map showing the areas of the castle which have been surveyed using GPR 
So far this year, geophysical survey using GPR has revealed several structures around the castle, which may include a well, a drain, and Victorian houses. However, we cannot know for certain what features are present until they are excavated, and this is unfortunately impossible in some areas of the castle. Advanced techniques such as GPR can hopefully be employed throughout the castle and grounds to help unravel more of Berkeley's rich history in the future. 

References:
Global GPR Services Inc. (Unknown). How a geophysical survey works. [Image]. Available at: http://www.global-gpr.com/gpr-technology/how-gpr-works.html. [Accessed on 06/06/16]
Google Earth. (2016). Satellite image of the Berkeley area with annotations. [Image]. Available at: https://www.google.co.uk/maps/@51.6895798,-2.4574207,421m/data=!3m1!1e3 [Accessed on 06/06/16]
Lambert Locations Pty Ltd. (2016).  Labelled diagram of a GPR. [Image]. Available at: http://www.lambertlocations.com.au/ground-penetrating-radar/groundpenetratingradar/. [Accessed on 06/06/16]
Tapatio. (2007). Example of geophysics data with annotations. [Image] Available at: https://en.wikipedia.org/wiki/Ground-penetrating_radar. [Accessed on 06/06/16]

-Hattie Ford

Monday, June 6, 2016

Buckles and Pins: Dress in the Medieval Period

Dress accessories, such as the wonderful Roman brooch (see fig. 1) which was recently excavated, are one of the most commonly found artefacts on sites such as Berkeley. While they are found throughout all periods of history (and late prehistory), they are particularly abundant in medieval contexts.
Figure 1. A Roman Brooch found in the upper half of the paddock. 
During the eleventh century, a trend developed towards more closely fitting clothes due to new innovations in tailoring, especially within the upper classes. This led to an increase in the use of buttons, pins, belts and buckles in an attempt to fit clothing closer to the body. In the medieval period, belts were a common dress accessory throughout all levels of society, regardless of gender or status, and as a result are the most common decorated metalwork accessory found in medieval contexts (Cassels, 2013: p.3). Those found are almost always made from base metals such as iron, copper alloys or tin alloys. Although buckles made of precious metals would have existed, they were less common and more likely to have been recycled, so are far less likely to be found during excavations (Cassels, 2013: p.5).   Below is an example of a post-medieval decorated plate found recently at Berkeley, which is intricately decorated and would have been used as a belt mount.
Figure 2. A decorated post medieval belt mount made from copper alloy. 

Belt buckles may also have had social significance as a method of expressing identity; the level of decoration on buckles can be used to determine the status of the owner, or even their religion, for example ecclesiastical priests living under monastic rules were not allowed to wear buckles with decoration whereas secular priests could. In the late medieval period, belt buckles were often left to beneficiaries in wills and were given as gifts during courting and marriage ceremonies (Cassels, 2013: p.4).

Another common dress type of accessory found from medieval and post-medieval sites are pins, such as this small pin found in a post medieval context (see fig. 3). Pins have not varied significantly in style over time, as shown by this pins similarity to our larger Roman pin (see fig. 4). It is likely that smaller pins would have been used to secure wigs by higher status members of society, while larger pins would have been designed to pin together cloaks, and it is these pins that are more commonly found during excavation. Other possible functions for pins have been suggested, such as to hold veils and fascinators and for use during garment construction. 


Figure 3. A small post-medieval pin. 
Figure 4. A larger Roman (or possibly Anglo-Saxon) cloak pin.  
These items are all grouped under the category of personal adornment items as they are used to adorn the body. They add a more personal story to the history of Berkeley we are revealing as they are the small everyday items that people chose to wear as part of their dress. It is easy to imagine someone searching for the beautiful belt buckle in fig. 2 or the hair pin in fig. 4 after losing it, while a smashed cooking pot would have been swept up and discarded. These items help our excavation bring the past inhabitants of Berkeley to life.  

References:
Cassels, A. (2013). The Social Significance of Late Medieval Dress Accessories. [Doctoral Dissertation]. Sheffield: University of Sheffield.

-Hattie Ford

Thursday, June 2, 2016

Archaeological interpretation, is it all just rubbish?

"And they always find in archaeology, a series of small walls. Every time, a series of small walls. 'We found a series of small walls, we're very excited. We think this proves that they had walls in olden days.' And then someone, very learned with glasses, says, 'The King and Queen entertained here. Courtiers and soldiers in this room. And elephants dancing hopscotch over there....' And you watch going, 'You're making this up, mate…. You don't know if it's true.'" (Izzard 1997).

The words of Eddie Izzard probably ring true for many people, how does “the learned person with glasses” know their interpretation that the series of small walls is in fact a building in which a King and Queen entertained their guests is correct? What evidence do archaeologists use to reach their conclusions? Here at Berkeley the western end of the trench consists of a large series of small walls (which is what brought Izzard’s words to mind) that we have the job of interpreting. Luckily for us we do generally discover a series of walls rather than just encountering one, or small sections of random walls, which makes our job a little easier.

One of the best examples of walls we have excavated in the last couple of years at Berkeley is the building we encountered in the north-western corner of the trench, see figure 1. One glance at the photograph may lead you to believe that interpreting the walls was easy, they form a large rectangular building, but do not be fooled rarely is archaeology ever that simple!


Figure 1: Remains of a building in the northwest corner of the trench. 

If you take a second slightly harder glance at the photograph it should become clear that the long wall running up the left hand side of the image is not in fact one wall, but two. The join between these two walls is highlighted in figure 2 below. So what appeared to be a simple series of walls is in fact more complex and poses a series of questions, all of which need answering in order to properly interpret these walls.


Figure 2: The red circle highlights the join between the two walls.

The first thing we need to determine is are we dealing with two separate buildings that happen to be about each other, or are we looking at a small building that was extended during its life? The easiest way to begin to get answers is to look at the two walls on the left hand side of the picture and work out how they relate to each other. Looking closely at the join between the walls it became clear that the lower section of the wall had a very large stone at its end (the end circled) which had been tied into the upper section of wall, so although they were on slightly different alignments the upper wall had been purposely built onto the end of the lower wall, suggesting that the original building was quite small and had needed to be extended at some point during its life.  

The next question is what period these buildings date to and then how long they were in use for. The easiest way to answer both of these is from the artefacts we excavate from within the occupation deposits within these buildings. The most reliable of these artefacts is the pottery, which although in most cases is not datable to within a decade can be dated to within 100 years or so, providing a date range. The pottery is sent to our ceramic expert once we have finished digging each year and he is able to tighten up the date ranges we (non-specialists!) give the pottery at the time it comes out of the ground. Most of the pottery found within the occupation deposits dated to the Tudor period, with some Late Medieval Tudor Green Ware, which was produced between 1380 – 1600AD (Laing, 2003). When the upper section of wall was lifted last year a piece of Tudor period pottery was found within the bonding material in the wall, indicating that the building had been extended during the Tudor period. The extension then does not seem to have been in use for very long as the 1544 map of the paddock does not show this building, indicating it had been demolished by this time.
So that leaves one final question to answer, what was this building used for? To answer this, we again turn to the artefacts to give us hints as well as the features within the building itself.


Figure 3: Under floor drains after partial excavation.

One of the running jokes between the students is that the corner where this building stands is drain city, with five drains having been recorded within the area, three of which are within the floor level of the building. The image above (fig 3), shows two of these drains after being partially excavated, although it looks like one drain, it is in fact two. The stones from the drain section on the right when first found were seen to cut through the filled up drain on the left. Both were covered in flagstones which would have formed part of the floor of the building.

The artefacts found within the occupation deposits are quite low in number and mainly consists of animal bone, a small amount of pottery and metal working waste. This is not typical of a domestic assemblage, as more pottery would usually be found in a domestic building. This lack of pottery coupled with all these drains leads us to suspect that this building had an industrial function, perhaps linked to metal working. Such an activity would require access to water and so a means of draining it away, which is why we have found so many drains in this area.

Hopefully next time the “learned person with glasses” offers their interpretation you will now understand the archaeological processes that have gone into forming that interpretation. However, one of the best things about archaeology is that interpretations change the more features we excavate and of course there are always little on site arguments when competing interpretations arise! The evidence can only lead us so far though and even among archaeologists there will never be full agreement over interpretations. The only way we will ever know for certain of course is to travel back in time, so I leave it up to the scientists amongst you to make that possible for us!  

Laing, L. (2003) Pottery in Britain 4000BC – AD1900 (Greenlight Publishing)

- Sian Thomas