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Dendrochronology 

Dendrochronology (tree-ring dating) has, in recent years, become a standard procedure in the investigation and interpretation of ecclesiastical properties.  InEnglandthis is largely the result of such studies being funded by English Heritage, most often as part of their grant-aided support of repairs and renovations to parish churches and associated properties, and to some of our magnificent cathedrals.

Some PCCs have themselves funded studies on their interesting features, and these often gain support from the wider community. Whilst the individual outcomes of dating a roof here, a door there, or a chest somewhere else are in themselves of great interest – we are now in the position of being able to draw on collections of data to be able to make interesting conclusions about the developments of styles and techniques that are applicable to a much wider group of buildings and fittings.

Similar studies have been carried out on the continent and a very welcome addition to our knowledge is the recent publication in English of “Roof Frames from the 11^th to the 19^th Century – typology and development in Northern France and Belgium” edited by Patrick Hoffsummer which is almost entirely based on church and cathedral studies, with dendrochronological dating providing the backbone to the study.

It is perhaps useful here briefly to discuss some of the limitations of the current ‘state of the art’. Tree-ring dating depends on having timbers with sufficient numbers of rings in them to be able to match the ring growth patterns with confidence, and the presence of sapwood, or at very least the heartwood/sapwood boundary on the timbers in order to be able to make reasonable assertions about the felling date ranges of the trees used. We are lucky here in that most construction timbers throughout the medieval and early post-medieval period were oak – a long-lived species with very clear rings, usually suitable for dating. Later imported softwoods may be suitable, especially if tree-ring chronologies are available in the source growth areas, so for example pines and spruces fromEuropemay be dated against European chronologies, giving additional information about where the timber originally grew. Whilst there is now an extensive database against which to match new samples, in some areas, even large timbers may lack sufficient numbers of rings, and human interventions in growth, disease, fire, lightning strikes etc. can all impact on tree growth to render the ring-width patterns undatable.

The great advantage of dendrochronological dating when it does work is the degree of resolution of the results. Where sapwood is present on several timbers (as it usually is when one looks carefully) it is possible to give felling date ranges (and hence dates of use of the timber) to within a couple of decades in many cases. When complete sapwood is present – as is often found for example on larger tiebeams – it is sometimes possible to give not only the year of felling, but potentially also the season of a particular year as the felling date of the trees used.

Whilst building historians are often very reliable at dating structures on stylistic characteristics, sometimes dendrochronology is the only sound way of establishing the correct dating. Take for example the splendid wooden tower at Blackmore in Essex, which Pevsner described as ‘one of the most impressive, if not the most impressive, of all timber towers of England’. Cecil Hewett (usually proved correct by subsequent dendrochronological dating) thought this tower dated to around 1480, whilst others asserted that it was pre- Black Death – i.e. early fourteenth century.  Tree-ring dating of some of the major timbers showed that the unusually large timbers used in the construction were felled over a period of three successive winters, and building took place in 1400, or within one or two years after this date.

This example also highlighted a phenomenon noticed by several dendrochronologists over the years – the tree ring patterns obtained by extracting cores from the major structural timbers generally matched closer to series from other ecclesiastical sites than with geographically closer secular buildings. This hints at different sources of timber or management of woodlands providing the source material.

In recent years there has been a lot of interest in dating bellframes and associated belfry floors, often when requests are made to consider inserting steel frames at lower levels within church towers. This not only allows a proper time framework for studying the development of such structures, but also may date the development history of the towers themselves, and highlight periods of activity in building and altering the structures which were not previously known about.

It is not just large structures like roofs, floors and bellframes that can be dated. Sometimes dating of such features can indirectly date other features, such as wall paintings which were in place before the timber construction was added, or which are clearly painted around an existing frame. Work on the roofs of Salisbury Cathedral showed that in some periods oaks were being imported from Ireland for major construction, and some of the earliest uses of Arabic numerals were dated to the early thirteenth century, suggesting that the master craftsmen were not only highly educated, but perhaps also had travelled widely.

Other wooden features, such as doors and church chests have been successfully dated in recent decades. We can now independently prove that we have at least two eleventh-century doors in daily use – the north door at Hadstock parish church, and the door in the vestibule to the Chapter House at Westminster Abbey, often confusingly referred to as the ‘Pyx’ door.  A number of church and cathedral doors and chests have been proved to contain timber from trees that grew far away in Europe, in what is nowGermanyandPoland. Whilst documentary records for the import of high quality boards from these areas have been known for centuries, the extent of this material has probably not been fully recognised. A church chest in Little Waldingfield (Suffolk) has carving that was almost certainly carried out inEngland, indeed it resembles stonework carving in the same church, but the boards used grew in what is nowPoland, as shown by the strong matches in its tree-ring data.

DrMartinBridgeis a part-time lecturer at theInstituteofArchaeology, UCL and a partner in the Oxford Dendrochronology Laboratory.

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