Create an account
Geologic time scale
A scale that divides Earth`s 4.6 billion-year history into distinct intervals of time.
Any method of determining whether an event or object is older or younger than other events or objects.
A principle that states that younger rocks lie above older rocks if the layers have not been disturbed.
the process of establishing the age of an object by determining the number of years it has existed
any naturally preserved evidence of animal activity (footprints/tracks or animal droppings)
Please allow access to your computer’s microphone to use Voice Recording.
Having trouble? Click here for help.
We can’t access your microphone!
Click the icon above to update your browser permissions and try again
Reload the page to try again!Reload
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Please upgrade Flash or install Chrome
to use Voice Recording.
For more help, see our troubleshooting page.
Your microphone is muted
For help fixing this issue, see this FAQ.
Star this term
You can study starred terms together