Dendrochronology

Archaeomagnetic intensity results from California and Ecuador: evaluation of regional data

“…Calibration across a relatively £at portion of the curve can lead to estimated calendar date ranges of 250 yr or more. Unfortunately, many of the 14 C dates used in our compilation studies have much larger laboratory standard deviations, leading to much larger calendar date ranges (500 or even 700 yr at the 68.3% con¢dence level). Finally, because the calibration curve is not monotonic, it is possible for a single radiocarbon date to have more than one possible calendar date.…”

“…Dendrochronology may yield dates accurate to a calendar year [14]. While a time lag between the death of the tree and its association with other cultural deposits must be considered, this method has the potential to provide very tight age constraints.…”

“…Where original references were provided, we have calibrated or recalibrated 14 C dates with the most recent CALIB v4.3 program of Stuiver and Reimer [21] and associated data sets [22,23]. Except in a few instances, this recalibration had very little e¡ect on placement of age mid-points, although it generally increased the age uncertainty.…”

“…An ideal date might come from a recently measured 14 C date (last 20 yr), combined with one or two other methods, reducing uncertainty to less than þ 50 yr. However, this kind of information is generally not available, and the fact remains that age Table 1).…”

“…By selecting only the most reliable data, we should produce a much less scattered record that more accurately represents the true paleo¢eld behavior. We can use updated ceramic chronologies, calibrate or recalibrate 14 C dates, and make cooling-rate corrections to existing data. Corrections for other factors cannot be made in retrospect, however, and some data must be excluded.…”