Rock Layers Geologic Time MS-ESS1-4
NGSS

Any method of measuring the age of an object, like tree rings or carbon dating
Absolute dating
Any method of measuring the age of an object, like tree rings or carbon dating, is called absolute dating. Absolute dating is when scientists figure out exactly how old something is by using specific methods like analyzing tree rings or measuring radioactive decay.

A fossil from an organism that existed for a short time, it is used to determine the age of other fossils
Index fossil
A fossil from an organism that existed for a short time, it is used to determine the age of other fossils. Index fossil. An index fossil is a tool scientists use to figure out how old other rocks and fossils are by comparing them.

The oldest rock layers are at the bottom and youngest are at the top
Law of superposition
The oldest rock layers are at the bottom and youngest are at the top. Law of Superposition. In geology, the law of superposition means that in any sequence of undeformed sedimentary rocks, the layers on the bottom are older than the layers on top.

Comparing the amount of radioactive and nonradioactive isotopes to determine rock age
Radiometric dating
Comparing the amount of radioactive and nonradioactive isotopes to determine rock age. Radiometric dating. Its a science method used to find out how old rocks or fossils are by measuring the decay of tiny particles inside them.