High-Precision ¹⁴C Measurement of Irish Oaks to Show the Natural ¹⁴C Variations from AD 1840 to 5210 BC

High-precision measurement of dendrochronologically dated Irish oak at bi-decade/decade intervals has continued in the Belfast laboratory, extending the 14 C data base from ca AD 1840 to 5210 BC. The dendrochronology is now considered absolute (see Belfast dendrochronology this conference) (Brown et al , 1986) and a continuous detailed curve is presented, showing the natural variations in the atmospheric concentration of 14 C over >7000 years. Each data point has a precision of <2.5., and some 4500 years have now been compared with Seattle, giving excellent agreement. Discussion of this data base and the justification of the claimed accuracy is given together with a comparison of other chronologies. Some of the advantages and limitations of the above are discussed.