Absolute dating methods determine how much time has passed since rocks formed by measuring the radioactive decay of isotopes or the effects of radiation on the crystal structure of minerals. Paleomagnetism measures the ancient orientation of the Earths magnetic field to help determine the age of rocks.

What do relative and absolute dating do?

Relative dating methods estimate whether an object is younger or older than other things found at the site. Absolute dating methods provide more specific origin dates and time ranges, such as an age range in years.