Dating, in geology, determining a chronology or calendar of events in the history of Earth, using to a large degree the evidence of organic evolution in the sedimentary rocks accumulated through geologic time in marine and continental environments.

What method is used to date the Earth?

radiometric dating methods To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.

Which EON is the longest?

Phanerozoic Eon In formal usage, eons are the longest portions of geologic time (eras are the second-longest). Three eons are recognized: the Phanerozoic Eon (dating from the present back to the beginning of the Cambrian Period), the Proterozoic Eon, and the Archean Eon. Less formally, eon often refers to a span of one billion years.

Why is Earths age important?

Earths age is relevant to biology because an old Earth is necessary for macroevolution to occur and also because some dating methods (e.g., dendrochronology, varves) use materials of biological origin. It is important to present this information, to demonstrate that macroevolution is plausible.