Every time a living being dies a stopwatch starts ticking. is used to determine the age of previously living things based on the abundance of an unstable isotope of carbon.

Serious technicians know how to compensate for this preference when dating samples.) With a half life of 5730 years, C in a piece of living organic matter will be the same as it is in the atmosphere but larger than in a piece of dead organic material.
A timber found in a home built 5730 years ago (one half life) would have half the C in the Earth's atmosphere has remained constant.
The isotopic distribution of potassium on the Earth is approximately 93% Ar nuclei that appeared as a result of radioactive decay would be trapped by the crystal structure and accumulate as the mineral aged.
In a hypothetical mineral sample with an initial population of 64 Potassium-Argon dating techniques have been used to date minerals covering the entire span of geologic history from 10 thousand to 3 billion years old.
Fossil fuels are the remains of long dead plants that were buried in sediment tens to hundreds of millions of years ago (coal being made primarily from land plants and petroleum from plankton and algae). Drinking ethanol (which is usually just called alcohol) is made from the fermented sugars of plants (grains like barley, wheat, rye corn, or rice; fruits like grapes or apples; vegetables like sugarcane or agave; or the nectar of plants collected by bees called honey). The carbon in the ethanol that came from plants will be relatively rich in C are not.
This means that the ethanol you might put inside yourself (the ethanol you might drink) will be slightly radioactive, while the ethanol you'd never consume (the ethanol you might wipe your skin with) will not be.
Immer wenn ein Lebewesen stirbt, beginnt eine Stoppuhr zu laufen.
Die Wissenschaft kann diese Uhr ablesen und so das Alter eines Fundes ermitteln. Source unknown — possibly das Museum für Vor‑ und Frühgeschichte (the Museum for pre‑ and early history) in Berlin.
Bacteria, fungi, and animals eat these plants and each other.