Radiocarbon dating of wooden beams at Herodium palace-fortress: Modeling tree-felling events and their implications on site chronology

The site of Herodium is best known for its impressive, well-preserved palace fortress, built by Herod the Great, towards the end of the 1 st century BC. The site's conical shape, artificially created to transform it into Herod’s monumental burial complex, is clearly seen from afar. The impressive preservation of wooden beams and posts at the site has allowed for a rigorous radiocarbon study of the beams’ felling dates and their potential implications for the timing of construction activities at the site. A total of 24 14 C measurements were performed on specific growth rings from 11 beams and posts, associated with six (sub) phases at the site. This level of detail, combined with Bayesian modeling and sensitivity testing of potential seasonal offsets, has revealed that the wood used at the site originates from four main tree-felling events. Apparently, the first event might have been as early as Alexander Jannaeus's time, in the first quarter of the 1 st century BC – a period not currently identified in the archaeological record at the site. The second reflects an extensive supply of wood, felled during the period corresponding to the beginning of the main phase of Herod’s massive construction activity (40–30 BC, approximately), followed by a possible third felling event towards the end of Herod’s life or shortly after. The fourth felling event was identified in beams used during the Bar-Kokhba revolt in 132–136 AD. However, the beams were felled several decades earlier, around 100 AD, between the Great Revolt (66–71 AD) and the Bar-Kokhba one, in a period characterized by limited documented occupation, indicating that the wood was used several decades after the trees were felled. The origin of some of those beams is probably from the extensive gardens Herod planted at the site.