Front

What is the process by which remains or traces of living things become fossils?

Back

Fossilization

Front

What are fossils used to determine the age of rock layers?

Back

Index fossils

Front

What are the divisions in the geologic time scale called that include the Paleozoic, Mesozoic, and Cenozoic?

Back

Eras

Front

What is the largest span of geological time?

Back

Eon

Front

What can be concluded about the top layer of rock seen in an undisturbed cliff wall?

Back

The top layer is younger than layers located farther down the cliff.

Front

What type of fossil provides evidence of the activity of ancient organisms?

Back

Trace fossil

Front

What is a fossil that is used to compare the relative ages of rock layers?

Back

Index fossil

Front

What is the term for the time it takes for half of a radioactive substance to decay?

Back

Half-life

Front

What is the geological time scale?

Back

A system of chronological dating that relates geological strata to time.

Front

What is the significance of index fossils in relative dating?

Back

They help to identify the relative ages of rock layers.