Medieval oak chronology from the Vilnius Lower Castle

Abstract

The paper describes the results of a dendrochronological investigation on historical oak (Q uercus robur L.) timbers from the Vilnius Lower Castle excavations. In Lithuania, oak was used only in specific cases during the Middle Ages. Therefore, historical material for tree ring chronology building is lacking. However, the construction of a local oak chronology is of great importance as it can help to determine the provenance of many imported timbers that are part of wooden cultural heritage in Western Europe. Oak samples make 9.2% of the analysed timbers excavated in the Vilnius Lower Castle territory – the largest present-day collection of historical timbers in Lithuania. The main material for Vilnius oak chronology was obtained from the ‘bridge foundation (BF)’ construction found close to the Royal Palace gate at a depth of 4–5 m. Ring-width series of the oak beams of the ‘BF’, together with other excavated oak logs were cross-dated and a mean chronology of 217-year length was constructed. The chronology was dated to AD 1202–1418 against the Baltic reference chronologies BALTIC1 ( t = 7.57 ), BALTIC2 ( t = 4.52 ) and WINCHCOL ( t = 5.74 ) (authors J. Hilliam, I. Tyers, D. Mills). The average date of the hardwood – sapwood boundary on the ‘bridge’ samples that have partially preserved sapwood is between 1406 and 1407. As the average number of oak sapwood rings is considered to be 16, the most probable felling date of trees used for the ‘BF’ is situated around 1423.