The discovery of radioactivity allowed geologists and paleontologists of the twentieth century to devise new dating methods, thus being able to assign absolute ages, in millions of years, to the divisions of the timescale.
Ukutholakala kwe-radioactivity kwavumela ama-geologists ekhulu lama-XNUMX kanye nama-paleontologists ukuthi benze izindlela ezintsha zokuqomisana ezinganikeza iminyaka ephelele (ezigidini zeminyaka) esikalini sesikhathi.