Principles of relative age dating
Long before geologists tried to quantify the age of the Earth they developed techniques to determine which geologic events preceded another, what are termed "relative age” relationships.
These techniques were first articulated by Nicolas Steno, a Dane living in the Medici court of Italy in the 17th C.
As the layers build up, they cement together to form sedimentary rocks.
A process called relative-age dating helps scientists determine how old these rock layers are.
The links below are animations illustrating the principles of relative dating (determining the sequence of events) and to images of real examples on which to try out the principles. Click on each of the five small images below to bring up an animation about the seas moving in and out.
Click and drag sideways to move the seas in and out, and drag up and down to see what's beneath the water.
There is no link back to this page and probably no need to return here, but if you want to revisit this page you can either click the Back button as many times as it takes to get here or close the program and start over.
Relative dating is used to arrange geological events, and the rocks they leave behind, in a sequence.