Extending the Calibrated Radiocarbon Record

The radiocarbon record is an important tool for accurate dating of climatic records, archaeological artifacts, and other records of past events. A calibrated record exists up to 24,000 years ago, but as [Bard][1] explains in his Perspective, extending the record beyond this time has been difficult. He highlights the record by [ Beck et al .][2], which covers 24,000 to 45,000 years before present. The record shows large fluctuations in the radiocarbon ratio and is an important step toward an extended calibrated record. [1]: http://www.sciencemag.org/cgi/content/full/292/5526/2443 [2]: http://www.sciencemag.org/cgi/content/short/292/5526/2453