To give an example if a sample is found to have a radiocarbon concentration exactly half of that for material which was modern in 1950 the radiocarbon measurement would be reported as 5568 BP.For two important reasons, this does not mean that the sample comes from 3619 BC: Many types of tree reliably lay down one tree ring every year.The Late Bronze Age to Iron Age transition in the coastal southern Levant involves a major cultural change, which is characterized, among other things, by the appearance of Philistine pottery locally produced in styles derived from outside the Levant.This transition in the coastal southern Levant is conventionally dated to the 12th century BC, based on historical and archaeological artifacts associated with the Philistine pottery.It is calculated on the assumption that the atmospheric radiocarbon concentration has always been the same as it was in 1950 and that the half-life of radiocarbon is 5568 years.
This is pit M13, inside the enclosure, which we dug in 2014.
Radiocarbon dating can provide a more precise independent absolute chronology for this transition, but dating for the period under discussion is complicated by the wiggles and relatively flat slope in the calibration curve, which significantly reduce precision.
An additional complication is that the stratigraphic record below and above the transition at this site, as well as at most other sites in the region, is far from complete.
The wood in these rings once laid down remains unchanged during the life of the tree.
This is very useful as a record of the radiocarbon concentration in the past.