Methods fall into one of two categories: relative or absolute.Before more precise absolute dating tools were possible, researchers used a variety of comparative approaches called relative dating.Avant que nous puissions vous montrer une liste et des photos de femmes qui vivent près de chez vous et sont prêtes à avoir des relations sexuelles dès maintenant nous devons nous poser quelques questions rapides.
Both methods date rock instead of organic material. But unlike radiocarbon dating, the older the sample, the more accurate the dating — researchers typically use these methods on finds at least 500,000 years old.
While K-Ar dating requires destroying large samples to measure potassium and argon levels separately, Ar-Ar dating can analyze both at once with a single, smaller sample.
Over time, certain kinds of rocks and organic material, such as coral and teeth, are very good at trapping electrons from sunlight and cosmic rays pummeling Earth.
Researchers can measure the amount of these trapped electrons to establish an age.
These techniques are accurate only for material ranging from a few thousand to 500,000 years old — some researchers argue the accuracy diminishes significantly after 100,000 years.