Tree ring dating reliability
The AD 2195 date match had a 75 ring overlap with the AD 1980 end of the master-ring sequence.The lowest match, AD 1483, had an 87 ring overlap with the AD 1396 end of the master sequence.The Bristlecone Pine master dendrochronological sequence that has been foundational for C-14 calibration has been based on 81 living-wood and 118 dead-wood specimens from the White Mountains of California.A calibration that falls within a time span that has been established by wood specimens that have been dated by unquestioned historical records (usually by cross-referencing C-14 ages) can be relied on to give a high precision estimate of real time.
Accordingly, any C-14 age is based on an assumption.However, these tests were not used when the original dendrochronological correction scheme for carbon-14 dates was established.It appears that this original scheme is subject to reevaluation.Forty-three of these matches were within the bark-date range AD 1483-1668, 23 within the range AD 1669-1771, and 47 within the future range AD 2078-2195.
Matches beyond the limits of the master chronology were made using a partial overlap with the 290-ring log.
The simplest calibration base for the initial C-14 is the assumption that throughout all past time accessible to C-14 dating, the C-14/C-12 ratio in the active carbon exchange system has been the same as it is at present.