How Old Is Rocks?

Using some simple mathematics, they can figure out how long ago the mineral first formed. It is possible to date rocks as old as four billion years this way. Absolute dating of rocks has provided many "tie points" for the relative time scale developed from fossils.

How old are rocks on Earth?

The oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history.

How do you calculate the age of a rock?

The age of rocks is determined by radiometric dating, which looks at the proportion of two different isotopes in a sample. Radioactive isotopes break down in a predictable amount of time, enabling geologists to determine the age of a sample using equipment like this thermal ionization mass spectrometer.