Earth History 4.75

Front

What process describes how a boulder can turn into silt as it moves down a river?

Back

The boulder hits other rocks or objects and breaks apart.

Front

What is a span of time within an era called?

Back

Period

Front

How have scientists determined that the Earth is about 4.5 billion years old?

Back

Radioactive dating.

Front

What is a common fossil found in many areas from a specific time, used to help identify the age of rock layers?

Back

Index fossil.

Front

What term describes any remains, trace, or imprint of animal or plant life preserved in Earth's crust?

Back

Fossils.

Front

What is the term for the preserved remains of ancient organisms?

Back

Fossils.

Front

What is the significance of index fossils in geology?

Back

They help identify the relative ages of rock layers.

Front

What method involves using the decay of radioactive isotopes to date rocks?

Back

Radioactive dating.

Front

What is the geological time scale?

Back

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

Front

What is the difference between an era and an epoch in the geological time scale?

Back

An era is a larger division of time than an epoch.