Busy. Please wait.

show password
Forgot Password?

Don't have an account?  Sign up 

Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
remaining cards
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
restart all cards
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Geologic Time


Geologic Time Scale Contains information about important events in earth's history. Divisions of time are determined by when major changes happened on earth.
Eon Largest unit of geologic time.
Era Second largest unit of geologic time.
Period Second smallest unit of geologic time.
Epoch Smallest unit of geologic time.
Absolute Age The approximate age of a rock or fossil in years.
Relative Age The age of a rock or fossil compared to other rocks or fossils (older / younger)
Half Life The time it takes for half of the radioactive, parent atoms to decay (change) to stable daughter atoms.
Relative Dating Using the law of superposition, the law of cross cutting, and index fossils in order to compare the age of rocks or fossils (older / younger)
Absolute Dating Using radiometric dating (half life) to determine the approximate age of a rock or fossil in years
Law of Superposition In undisturbed layers of sedimentary rock, the oldest rocks are at the bottom
Law of Crosscutting When a geologic feature (intrusion, erosion, fault) cuts through a rock layer, it is younger than the rock layer it cuts through
Index Fossil Fossil of an organism that lived for a relatively short time, but was widespread.
Trilobite An example of an index fossil
Created by: cyclonescience