Dating mt st helens rocks
You find a bone fragment and through analysis you determine that it contains 13% of its original carbon-14.
The half-life of carbon-14 is approximately 5,730 years. Start with the equation for continuous growth and decay: Thus the bone is approximately 17,000 years old.
Carbon-14 decays almost completely within 100,000 years of the organism dying, and many fossils and rock strata are hundreds of times older than that.
To date older fossils, other methods are used, such as potassium-argon or argon-argon dating.
Carbon-14 dating has an interesting limitation in that the ratio of regular carbon to carbon-14 in the air is not constant and therefore any date must be calibrated using dendrochronology.Some isotopes have half lives longer than the present age of the universe, but they are still subject to the same laws of quantum physics and will eventually decay, even if doing so at a time when all remaining atoms in the universe are separated by astronomical distances.