Dendrochronology and the study of crannogs
The dendrochronological potential of wood from two crannogs was evaluated. Consisting predominantly of non-oak species with fewer than 50 year-rings, the assemblages required the development of new techniques and approaches. The problem of validating cross-matches between short ring sequences was resolved by a new methodology based on internal consistency. A group of internally consistent sequences contains no conflicting chronological relationships in the full set of its pairwise correlations. The SORT.STRING program, designed to identify sets of internally consistent groups in large data-sets, was tested on two 'known' data-sets. It successfully identified the correct chronological relationships in these data-sets. Applied to the assemblages from the crannogs, it identified small, mutually exclusive groups of sequences which could not be satisfactorily merged to form a site chronology. Reasons for this are explored and indications for future work identified. The dendrochronological potential of alder (Alnus glutinosa)was examined and a suitable methodology developed. Cross-correlation and chronology formation are possible but extreme ring-width values, i.e signature years, and compression of the outermost rings re identified as problematic features. Evidence for woodland management practices in the crannog assemblages was evaluated. A model for woodland management was formulated, on the basis of two samples of modern coppiced material. This distinguishes between adventitious and formal coppice. Application of the model to hurdles found on the Irish crannog indicates that they are the products of adventituous coppice.