Major dating methods used by archaeologists
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.Paleontologists still commonly use biostratigraphy to date fossils, often in combination with paleomagnetism and tephrochronology.A submethod within biostratigraphy is faunal association: Sometimes researchers can determine a rough age for a fossil based on established ages of other fauna from the same layer — especially microfauna, which evolve faster, creating shorter spans in the fossil record for each species.Thermoluminescence: Silicate rocks, like quartz, are particularly good at trapping electrons.
Researchers who work with prehistoric tools made from flint — a hardened form of quartz — often use thermoluminescence (TL) to tell them not the age of the rock, but of the tool.
Certain unstable isotopes of trace radioactive elements in both organic and inorganic materials decay into stable isotopes. By measuring the proportion of different isotopes present, researchers can figure out how old the material is.