Relative dating diagram
The laws of physics and chemistry that governed geologic processes in the past are the same as those that govern processes now and in the future.
The geologic timescale is a chronology (calendar) of events on Earth based on obtaining ages of past events.
Absolute dating, also called numerical dating, arranges the historical remains in order of their ages.
For each dating or chronological method there is a link in the box at right to take you to that section of this page.
In example A, the age of the shale is bracketed between two lava flows, one older than the shale, and one younger than the shale.