C (the period of time after which half of a given sample will have decayed) is about 5,730 years, the oldest dates that can be reliably measured by this process date to approximately 50,000 years ago, although special preparation methods occasionally make accurate analysis of older samples possible.

How far back does radiocarbon dating work?

55,000 years ago The work combines thousands of data points from tree rings, lake and ocean sediments, corals and stalagmites, among other features, and extends the time frame for radiocarbon dating back to 55,000 years ago — 5,000 years further than the last calibration update in 2013.

How far back can absolute dating go?

about 60,000 years Limitations. The relatively short half-life of carbon-14, 5,730 years, makes dating reliable only up to about 60,000 years.