Carbon dating is useful for old bones and wood because carbon-14 has a half-life that is:

1. A dating method needs an isotope that decays on the timescale being measured. 2. Because the half-life of carbon-14 is long, it is used to date formerly living objects such as old bones or wood. 3. That half-life is about 5,730 years, which suits archaeological timescales. 4. Uranium-238 has a half-life of 1.25 billion years, far longer, which suits dating rocks instead. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 2 'The Chemical Foundation of Life', sections 2.1-2.3_