Which factor limits radiocarbon dating to about 50,000 years?

• A. The half-life of carbon-14
• B. The atmospheric carbon-14 content
• C. The Earth's gravity
• D. The carbon-12 abundance

Answer: (A)

Radiocarbon dating works by tracking the decay of carbon-14 in once-living material. The key factor is the half-life of carbon-14, which is about 5,730 years. After roughly 50,000 years, only a tiny fraction of the original carbon-14 remains, so the remaining signal becomes very weak and difficult to measure accurately amid background noise and contamination. That dwindling signal sets the practical limit for reliable ages in this method. Variations in atmospheric carbon-14 content can affect pinpoint ages and are corrected for, but they don’t determine the dating horizon. The Earth’s gravity or the amount of carbon-12 don’t impose this limit.