New developments in the interpretation of dendrochronology as applied to oak building timbers

Thesis

The ring-width data for 3313 oak samples with complete sapwood were studied from mainland Britain, together with 1067 additional samples from various other European locations. Regression analysis of the material showed that there was a relationship between the number of sapwood rings, the mean ring width of the heartwood, and to a lesser degree the number of heartwood rings present. A method of producing models using datasets where complete sapwood was available was devised, which produced individual felling date ranges for each sample. One model was found to be suitable for all of England and Wales from the Roman period to the present, and produced a success rate of 96%, with 94% of the samples tested giving a felling date range narrower than the 36-year empirically calculated range previously used.

Analysis in the variation of felling dates within individual phases of construction found a significant proportion of timbers had been stock-piled. A method was developed of combining individual felling date ranges using Bayesian methodology, and allowing for the possibility of stockpiling, dramatically reducing the usual empirically-derived felling date range. This reduction was as much as 90%, depending on the number of samples combined. Testing of this procedure with independent data has achieved a 95% success rate. Samples exhibiting extreme or sudden changes in growth rate were found to be unsuitable, as well as those from cathedrals due to their exceptionally long periods of construction.

The comparison of over 100 examples of dendrochronologically-dated buildings with independent dating evidence showed a good correlation between felling and construction dates. Analysis of these demonstrated that most structures were erected in less than half a year, and usually during the summer season.

The combination of the various aspects of this research has resulted in a better understanding of how medieval buildings were constructed, and allows an improved interpretation of tree-ring dates, including both precise and estimated felling date ranges.

Authors: Miles, D; Miles, Daniel William Henry

• Publication date: 2006
• DOI: 10.5287/ora-y07626awd
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Oak; Dendrochronology