Absolute age dating
In a way this field, called geochronology, is some of the purest detective work earth scientists do.There are two basic approaches: relative age dating, and absolute age dating.An element is defined by the number of protons it contains. For carbon-14 decay, each carbon-14 atom loses an alpha particle. This is illustrated in Figure below and at the link below.[Insert a link to an animation of the decay of carbon-14 to nitrogen-14.] The decay of an unstable isotope to a stable element occurs at a constant rate. The decay rate is measured in a unit called the half-life.All atoms of a given element contain the same number of protons. Atoms of an element with different numbers of neutrons are called isotopes. The half-life is the time it takes for half of a given amount of an isotope to decay.
For example, the half-life of carbon-14 is 5730 years. Over the next 5730 years, half of the remaining amount will decay. How many grams will there be in another 5730 years?The narrower a range of time that an animal lived, the better it is as an index of a specific time.No bones about it, fossils are important age markers.It’s based either on fossils which are recognized to represent a particular interval of time, or on radioactive decay of specific isotopes. Based on the Rule of Superposition, certain organisms clearly lived before others, during certain geologic times.After all, a dinosaur wouldn’t be caught dead next to a trilobite.