Learn more about working in the field at Blackfriary!
The feature is our smallest unit of investigation. However, the site is excavated/managed as a series of “Cuttings”, to which excavation teams are assigned. A cutting is an arbitrary area, decided upon by the site directors, which is open to investigate a particular area/research aim, as part of the overall research strategy. For example it might be decided to excavate a 5m by 5m cutting over a specific part of the church to better understand burial practices in the area. IAFS staff decide on the size, shape, and location of any cutting and assist students in laying them out according to the site grid.
Cuttings can themselves contain small investigative units, such as sondages, and/or in exceptional circumstance an internal grid system. A sondage, if you like, a cutting within a main cutting, designed to investigate a specific feature or set of features. Their application will depend on the research questions being asked. An internal grid within a cutting is occasionally used (with alphabetic identifiers for specific spatial units) to assist with artefact/ecofact collection. A sondage, grid, or internal grid reference can NEVER be used to replicate a feature number during archaeology recording.
Once a cutting has been established, excavation typically commences with the removal of the sod/grass and topsoil. Removal of the sod is aptly called “de-sodding”, an exercise achieved by simply cutting the sod into small squares (making sure they are light enough to lift) using a spade. Once the sod is stripped, the topsoil is removed using a combination of mattocks, shovels, and garden hoes. The use of these tools is simple but still requires some level of technique to maximize efficiency and avoid injury. After the topsoil is removed either rubble deposits (dating primarily from the 18th century) or older archaeological features are typically exposed. At this point the digging methodology may switch to smaller hand tools.
This is where things start to get exciting! The basic features encountered will include cuts (or dug/negative features such as a ditch or pit), fills (soil/stone etc. placed backed into cuts), deposits (soil/stone etc. not in a cut), and walls (the latter pertaining to the friary and later buildings). As a cemetery is located on the site both intact burials and disarticulated human bone are also regularly exposed. In the course of excavation all our recording techniques are used to document what has been exposed and ultimately taken apart.
Excavating burials is one of the more highly skilled and paperwork heavy jobs on site. Before any bone is lifted, the burial is fully exposed and fully recorded with photographs, a plan, and a burial sheet. All the field notes and the information on the burial sheet must be as complete as possible.
The burial will be recorded on a pro-forma burial sheet. This will take time as most of it can be filled in before the bone is lifted, but other parts must be returned to once the burial has been taken up. There are three that we use as appropriate – adult, juvenile and infant burial sheets. The sheet ultimately must be filled in its entirety and an example of the kind of information required is shading in the bones that are present .Using the skeletal diagram on the sheet. This may be amended subsequently if more bone is found in soil samples, such as toe or finger bones,. Students are instructed to take levels of the skull, the sacrum (if possible), and the feet. In the case of incomplete skeletons this may vary. They are also to take levels on any artefacts accompanying the burial. Multiple photographs of each burial are required. These are taken with and without accompanying scale, arrow, and board. With burials it is preferable to take a photo with just the scale for publication purposes. A plan indicating the position of the burial, grave cut (if visible), as well as coordinates and levels are required.
When it comes time to lift the burial the bones must be lifted extremely carefully in a systematic manner. Whenever possible we always try to start with the skull. We bag bones as we remove them and we are sure to place them in specified, pre-labelled bags according to the side of the body and body part, i.e. left hand, left foot, left ribs, etc. We must be diligent and be sure that all the filled bags are properly labelled and kept together in a single box. Finally, the grave cut, if discernible, is planned and the profile is drawn.
In post-excavation human bone is cleaned for precisely the same reasons as animal bone, i.e. to prevent further damage and to assist with specialist analysis. However, because of ethical considerations surrounding the treatment of human remains, there are additional protocols that need to be addressed during the washing process. Prior to washing any human material, it is important to firstly examine the external surfaces of the bone to ensure that there is nothing adhering to the bone that may be of value to later analysis. If any adhering substances are identified they are carefully removed and this material along with the surrounding soil is placed in a clearly labelled bag/container (transferring all the information from the original bag to the new bag with an inclusion of an additional note identifying the retained substance). Having determined that a bone is free of adhering substances it is suitable for washing. Bones that are extremely fragile are cleaned using soft bristle brushes to gently remove the soil from the bone surface.
The process for washing human bone is as follows. A clean basin is filled with tepid or cold water and a suitable drying tray is arranged. The tray is lined with cloth and it is imperative that only one burial will be assigned this tray. Each skeletal element must be clearly separated using dividers. All the information written on the bag to be washed is copied onto a permatrace label. This label will identify the material placed on the drying tray. Next the information is entered in the Bone/Burial Washing Register, ensuring that the entry is in the correct cutting and the appropriate section. Prior to washing a skewer is used to loosen/detach any large clumps of soil adhering to the bone surface or lodged within the bone cavity. Having removed excess soil from the bone, using lukewarm water (without any detergent or additives) and a soft bristle brush the bone’s surface is slowly and gently washed, removing the remaining soil. Then each cleaned bone is placed in the drying tray. After a bag is complete the water in the basin is poured through a sieve to capture any bone fragments that may have dislodged during the washing process. The tray is then placed inside a dryer. Once dried, they are placed back in their cleaned original bag. All bags from the burial are to be kept together in a box.
Samples are taken to reconstruct the ecological, environmental, economic, and social stories of the site/excavation. Archaeological sites can be simple or complex- in terms of features, chronology, the chemical and physical properties of the deposits, and the site formation process. These factors will influence the preservation or loss of different materials. In determining the most appropriate sampling strategies for a site, the excavator should:
Some environmental remains are not homogenously distributed through a deposit, in these cases several samples from the same deposit may be taken. We have several different types of materials that are commonly sampled at the Black Friary. These include faunal bone (butchered and not butchered), and soil samples taken for retrieval of various ecofacts such as insects, plant macro, wood/charcoal, pollen/spores, cremated bone, metallurgy waste, and molluscs. The collection of sample types should be seen as a ‘bulk’ collection- be that a 1 liter bag or 60 liters. When sampling, say for charcoal or molluscs, for example, individual pieces are never handpicked from the matrix. Handpicked samples are biased and may contribute little to the ecological or environmental information you are pursuing.
Where a fill is deemed worthy of assessment and is less than 30 liters in volume, then 100% is sampled. Students use black marker to write on the sample bags/buckets. Every sample is given a sample number and registered in the sample register. When labelling samples, we use a lozenge shape symbol to contain the given sample number. The purpose of this is simply for ease of recognizing the sample number amongst the other information provided on the bag or bucket.
When processing soil samples we consider the intended analyses for the sample, as this will determine the type of onsite processing that ensues. As well as processing for ecofacts as outlined above, soil can be collected for a suite of analysis such as particle size analysis, pH analysis, or to conduct analysis on chemical composition. Two processes that are generally employed on site are wet sieving and coarse sieving. When wet sieving the samples is poured directly on the sieves of desired size and a water hose is used to wash it down. The residue in the sieve is then scanned for archaeological material. To coarse sieve the samples is poured directly on the sieve of desired size and a student would use his or her hands or trowel to encourage the soil through the mesh. The sieve is under constant observation for archaeological material.
The importance of the archive ought to be stressed. In essence we are de-constructing the site in a controlled manner in the pursuit of knowledge. As we excavate we ‘preserve’ the site through the records we take – commonly referred to as Preservation by Record. It is crucial that the records we generate are not only meticulously gathered, but also that they survive for a long time and can still be viewed in 50 or 100 years! The registers used on site include: Feature Register; Planning (Drawing) Register; Photograph Register; Sample Register; DHB Register; Bagged Finds Register; Burial Register; Stained Glass Registers; Plaster Register, Architectural Fragments Register, various washing registers and other sheets or registers, as required! The most fundamental element of record is the feature. As features are excavated, students are tasked with their identification, characterization, and documentation. The records taken can be broken down into four broad categories: written, drawn, photographic, and burial. Burial records will be covered in a later post concerning human remains.
The basic unit of recording is the feature number, everything else stems from this first step. Records for each feature generally begin once it has been identified on the ground and finish once the feature is fully excavated. To record a feature a student will begin by taking the next available feature number in the feature register. Then the proper record sheet is collected from the office. There are four different types of sheets to choose from: skeleton, wall, cut, and fill/deposit. Essential information on the sheet includes: cutting number, feature number, location on site grid, date started, excavator, feature description, levels, etc.. There are several prompts on the sheet. Each feature sheet has a specific table to record numbers that have been documented in other registers. In turn all these registers must refer back to your feature number. For example one must record all photos, bagged artefacts, samples and/or disarticulated human bone (DHB) taken from within the feature on the feature sheet. These should have already been recorded in their own registers – artefacts in the Finds Register, samples in the Samples Register, and photographs in the Photo Register and so on. Typically, one may need to return to the sheet on several occasions during the course of the excavation.
Features on site need to be understood in relation to each other spatially (which can be achieved by planning) as well as chronologically. The latter is important to understand when, and in what order, events (recorded as features) happened on site. Chronology is recorded archaeologically as stratigraphic relationships, which are documented using a matrix. Stratigraphy is a key concept in archaeology, but takes practice and experience to fully understand in the field. All features must be dealt with as separate instances, but their stratigraphic relationship to each other needs to be understood and recorded carefully.
We now move from the written to the drawn record. To complete a site drawing one must first learn the principle of the site grid, and how to establish height above sea level (Ordnance Datum) with an automatic/dumpy level (called taking a level). The site grid on the Black Friary allows us to ensure all our spatial recording/planning can be understood relative to the national grid, and that feature positions can be understood relative to each other. As with many sites the Black Friary grid is arbitrary. By this we mean a surveyor has laid out a grid with values that do not directly relate to the national grid. Crucially however, the site grid is understood in relation to, and can be overlaid on, the national grid. On the ground the grid appears as a series of pegs, generally at 10m to 20m intervals (to which you can attach tapes for planning). Each of these pegs has an easting and northing value written on it, which uniquely identifies it. These are like X and Y coordinates so the easting is written first, followed by the northing (contrary to what you might think). The grid is used to help us lay out our cuttings. It is essential that cuttings have straight sides and right angles, so that they can be accurately represented on plans. Right angles on the ground can be achieved with tapes using an easy technique based on the Pythagorean Theorem. The Pythagorean Theorem is a technique that is used in planning/surveying on this and other sites very frequently. If available, an electronic survey device, such as a total station or GPS, should be used to set out/check the site grids and cuttings, especially at large open-area excavations or where there is a significant slope (slopes make the measurements taken using tapes inaccurate). Surveys of the site are also periodically undertaken using an electronic device.
Drawings are made on planning boards (gridded at 1cm intervals) covered with a polyester drawing film (permatrace); the permatrace must be taped into place tightly (to ensure accuracy), and remains on the board until the drawing is finished. When setting up a drawing, one needs to select a drawing board (size) appropriate for the scale of the drawing. The most frequently used scales are 1:10, 1:20 and 1:50 (depending on the level of detail required and the size of the area being planned; all planning is strictly done using the metric system). Next one would go to the planning register (a list of all drawings from the excavation) and take the next available drawing number and sheet number (multiple sheets may be required for single plan in certain instances). We always ensure that all the required information is included in the top right corner of the drawing, such as: plan number, site name (Black Friary), ministerial consent number (E4127), cutting/feature number, scale, grid location date, initials, etc. Next we mark at least two grid pegs on the plan (more pegs are preferable) and label them with the proper E/N coordinates. All plans include levels which are clearly indicated. There are a number of different drawing/plan types. Typically students will only use three – plans, sections and profiles or elevations.
Plans record the aerial or bird’s eye view of a site or feature. Where possible, we try to always plan on established grid lines. A section is a vertical recording of the face of a feature (or set of features [for example a cutting side]), which have been partially excavated (think of slicing through a cake to reveal the layers of cream, sponge, frosting etc.). Profiles record the vertical component of a feature (or set of features). Typically they are used for features which have already been excavated or to record surface topography, for example of a bank, hummock or ditch that is visible in the topography of the field. The methodology employed is the same as that outlined above for recording a section. An elevation may be drawn of a wall face or other built feature using the same methodology.
In addition to written and drawn records photographs of features/the site are also taken. This is not as simple as shooting off a snapshot! Firstly all photographs are recorded in the photo register. Like other registers this asks for the Cutting number, feature number, initials and the date, as well as a summary of the shot (for example ditch F606 during excavation). As well as feature specific shots students are encouraged to take general ‘progress’ shots of cuttings as digging progresses, or if there is a change in the digging circumstances (for example if there was heavy rain and the cutting flooded!). For progress shots the photographic protocol is more relaxed, for example tools and people can be in the photo. However, for record shots a set of rules need to be adhered to. The area being photographed should be ‘clean’, devoid of tools, coats, hats, water-bottles, people, spoil etc. If taking photographs of features, these should be clean and well defined. If sunny, students are encouraged to choose an angle to best show the subject. We try to avoid taking photos when the sun is low in the sky. If there is bright sunshine, we cast a shadow over the subject; however we are sure that this covers the area to be photographed. Overcast conditions are ideal. At least one shot (if multiples are being taken) must include the site photo board, which must display the excavation number, feature/cutting number, date and initials. This board may also include the stage of works (for example pre-excavation, post-excavation etc.). At least one shot should contain photographic scales and a north arrow (the latter pointed in the direction of true north). At the end of the day, photos are downloaded to the site office computer and hard drive and completed photo register pages are filed.
Effective management of post-excavation is as important as well implemented excavation processes to the overall success of the project. This is where we process artefacts and samples. Samples are discussed in another entry. An artefact can be defined as:
‘[T]he general term which applies to any object which has been made, or altered, by human agency’ – A Dictionary of Irish Archaeology, Laurence Flanagan.
During excavation, each student uses a finds tray (the same as a garden seed tray) for the collection of objects on site. A different tray is used for each feature being excavated. The tray on site is labelled with all the necessary information to identify where the contents have come from, including: excavation number, site name, feature number, date and initials. Once finds have been excavated and gathered in the finds try they need to be sorted, bagged and registered. All trays are dealt with in the site office. Here we sort through the finds tray to determine what to keep and register. This is where we differentiate which are artefacts and which are samples. Then we group the finds in the tray by type, i.e. all metals, ceramics, stone etc. We try to distinguish between different pottery types, keeping medieval and post-medieval separate where possible. Then we bag all like items from any given feature together, e.g. all medieval pottery from F301 on a given day will be bagged together. At IAFS we complete a bagged finds register on site. It comprises eight fields and its function is to assist in the general overview of the site and to provide basic information on certain features at a glance. It is also an important tracking system for the movement of materials and gives an indication of quantities for post-excavation processing.
Over the past number of years, we have been finding a large amount of stained glass fragments at Black Friary. These fragments are recorded in the ‘Stained Glass Register’. We keep all the glass that is found during excavation as it is important that notes on even the smallest fragments are recorded in the feature records (feature sheets and site notebooks).
We have also been finding considerable quantities of painted plaster, from the interior walls of the church and other buildings. Again we record all the contexts in which the plaster was found and retain only those pieces which are polychrome, that is where more than one colour, indicating a pattern, has been used. These fragments are registered in the painted plaster register.