CONTRIBUTED BY: THOMAS HIGHAM

Introduction

The journal Radiocarbon was begun in 1958, its main function being the publication of radiocarbon date compilations produced by the world's laboratories. Today, there are many laboratories and few publish comprehensive lists of results, there are far too many dates being calculated for this to be achieved. The publication of radiocarbon dates rests almost totally with the submitter of the material. In many instances, researchers have in recent decades, neglected to publish relevant data describing the sample, laboratory and reference numbers, provenance and reservoir correction details. Such practices seriously undermine the value of radiocarbon dates because they lack a meaningful context. Some of the problems associated with interpreting the corpus of radiocarbon data obtained thus far concern variation in reporting. These may be involved with uncertain reservoir corrections, especially for shell dates, corrections for isotopic fractionation and failure to specify whether the old or new half-life was used.


Publication of dates

There are some crucial pieces of radiocarbon information that ought to be published in papers and media which present radiocarbon dates:

The CRA must always be given in a publication. Unlike calibrated age ranges, CRA's never change (unless laboratories recalculate them).

In terms of calibration, the choice of what to publish is more complicated. Calibrated data changes with successive calibration curves, therefore it is important to inform the reader of the calibration curve which was used, as well as the basic data concerning the conventional radiocarbon age and lab number. In cases where the sample is from the Southern hemisphere it is important to note whether an offset was deducted to account for the difference which exists between the activity of the two hemispheres. In dating shell, note should be made of whether the conventional radiocarbon age was corrected prior to calibration or whether corrections were made using a local delta-R value. In the calibration pages in this server, information regarding publication of calibrated data is being constructed. Generally, the term "Cal AD" or "Cal BC" is given to describe calibrated age range data. There was a proposal mooted recently in Britain to use the upper and lower cases of "BP" to describe calibrated and conventional dates, bp for instance was to refer to calibrated dates, BP to conventional dates. This was never adopted by the international Radiocarbon community.

International Radiocarbon conferences are held every three years. Here, specialists in the field present papers, new techniques and results for peer perusal, workshops and discussion. In addition, computer databases containing extensive radiocarbon date compilations should become more widely used. An example of such a database can be seen at the University of Waikato Radiocarbon Dating Laboratory where dates measured there for the New Zealand prehistoric sequence have recently been brought online. There are also online radiocarbon databases at the National Geophysical Data Center - Paleoclimatology Home Page and National Geophysical Data Center - Radiocarbon datasets. In addition, there is a searchable database of radiocarbon measurements for archaeological and vertebrate palaeontological sites in North America at the Canadian Museum of Civilization. The Radiocarbon dates online (RADON) database comprises more than 2.000 Neolithic and Early Bronze Age data sets from Germany, Switzerland, the Netherlands, Denmark and adjacent regions.

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