Much of the special interest of timber buildings lies in how they differ in form and appearance from region to region over time, with buildings generally reflecting local tradition and locally derived building materials. Studies in Kent, Hampshire, Surrey and Shropshire have identified datable styles of building, but there has been little study or tree-ring dating in Gloucestershire which also had a strong tradition of timber building.
Gloucestershire’s early medieval buildings which retain significant early fabric are of particularly special interest in terms of shedding light on the development, innovative use of structural techniques, and use of buildings.
Three main techniques are to be undertaken as part of our project to help promote our understanding and appreciation of the buildings in the project:
- Building recording
- Tree-ring dating
- Archaeological photogrammetry
A systematic recording of the timber-framed features in the buildings of this project will be undertaken to help assess the significance of each building and identify datable patterns of style in timber-framing. A simplified plan identifying the early timber-frame layout of each building will be produced (Figure 1).
To enable comparisons between counties and regions, the use of a common nomenclature is critical and therefore the Council for British Archaeology (CBA) Illustrated Glossary of Timber-Framing terms is used where possible.
The character of many timber-framed features varies both regionally and with time, but these patterns have often been difficult to define. The Building Archaeology Research Database (BARD) has been developed to provide a publicly accessible online database for the systematic recording of buildings. BARD allows searches for specific timber-frame features linked to other criteria (such as parish, county, and method of dating, etc.). It provides an archive for the recording of buildings and allows easy comparisons between different areas.
BARD has been specifically developed to help encourage people’s involvement in building archaeology. The BARD ‘Tick-Box’ recording sheet is used to systematically record all the key dating features, with the information recorded to then be entered into BARD for subsequent analysis. An illustrated glossary is also used in tandem with the ‘Tick-Box’ recording sheet to help simplify the identification of building features.
All recording data will be entered onto the Building Archaeology Research Database (BARD) a free on-line searchable archive located at www.buildingarchaeology.com. All building recording reports are to be archived with the Historic Environment Record held at Gloucestershire County Council Archaeology Service.
Tree-ring Dating (Dendrochronology)
Many people at some time have counted the number of rings in a felled tree to see how old the tree was (Figure 2). Assuming the year the tree was felled is known, you can count back from the outermost ring to the centre and establish exactly the year the tree was planted or germinated. This laying down of annual growth rings is the fundamental basis of the science of dendrochronology.
In dendrochronology annual rings are not just counted, the width of each and every tree-ring is accurately measured in sequence (Figure 3). Ring width is determined partly by the weather in the year it grew, therefore in a good year a wide ring will tend to develop, and conversely in a bad year a narrow ring will develop. A consecutive series of 70+ rings forms a unique ‘bar code’ or ‘tree-ring chronology’ of wide and narrow rings. Using dendrochronology a 70+ series of tree-rings of unknown date can be matched and dated against a series of tree-rings of known date (called a tree-ring reference chronology).
In the UK we have a remarkable reference chronology for oak extending back to 7,700 BC. Therefore, it makes little difference if the technique is called to analyse trees growing today, those used in medieval timber-framed buildings, or those from the Iron Age sometimes preserved in a peat bog.
In this country dendrochronology is most commonly used to identify the precise year of construction of medieval buildings (Figure 4). However, archaeological timbers are also routinely dated such as those used in the construction of the Seahenge at Holme-next-the-Sea, Norfolk which is dated to 2050 BC and reveals evidence for coppicing in the Bronze Age (Figure 5).
All tree-ring dates from the project will be published in Vernacular Architecture (a scientific journal) and entered onto the Dendrochronology Database (the national database located at https://archaeologydataservice.ac.uk.
Photographs of the buildings and timber-framed features will be taken. Where in the internal features of building of particular interest are not generally accessible a visual record will be undertaken using digital photogrammetry. This process turns a large series of digital photos in to accurate 2 or 3D models of the building (Figure 6 & 7).
This technique is a way to document our heritage in all its fine details. With the development of digital cameras and available software the use of photogrammetry has been made much more accessible.