Skip to page content

A Journey to a New Land

Woolly Mammoth
Multimedia Library

Dr. Erle Nelson

Department of Archaeology, Simon Fraser University

Calibrating Radiocarbon Dates

Radiocarbon dating does not measure time in real years; it measures time in a scale we call radiocarbon years. That needs to be really kept in mind at all times - that we are not measuring real time when we measure radiocarbon dates. We’re getting a false scale in that sense. What is amazing, actually, is that the radiocarbon scale works as well as it does for most of the time that we know. It’s not very far off in comparison to real years. But it’s sufficiently far off in a number of circumstances that it causes real troubles in archaeological interpretation.

One of the major achievements has been to work out a mechanism by which we can calibrate, or correlate, the radiocarbon time scale together with the calendar years that we are so used to using. That’s been done by radiocarbon dating a very large number of known-age tree rings. That work has taken place on the west coast of North America in Seattle, and in Belfast, Ireland and places like that. From that work we have a global calibration by which we can take a known radiocarbon age and then calibrate it to get from that a real calendrical age.