Paleomagnetism is often used as a rough check of results from another dating method.Tephrochronology: Within hours or days of a volcanic eruption, tephra — fragments of rock and other material hurled into the atmosphere by the event — is deposited in a single layer with a unique geochemical fingerprint.Egyptologists, for example, created a relative chronology of pre-pharaonic Egypt based on increasing complexity in ceramics found at burial sites.
Researchers can measure the amount of these trapped electrons to establish an age.
But to use any trapped charge method, experts first need to calculate the rate at which the electrons were trapped.
When it comes to determining the age of stuff scientists dig out of the ground, whether fossil or artifact, “there are good dates and bad dates and ugly dates,” says paleoanthropologist John Shea of Stony Brook University.
The good dates are confirmed using at least two different methods, ideally involving multiple independent labs for each method to cross-check results.
This includes factoring in many variables, such as the amount of radiation the object was exposed to each year.