Geological Timescale

Front

How old is the Earth?

Back

Approximately 4.6 billion years old.

Front

What is the oldest era in the geological timescale?

Back

Precambrian.

Front

What determines when an era or period begins or ends?

Back

Mass Extinction.

Front

What is the main purpose of the geologic time scale?

Back

To organize the major eras of Earth's history.

Front

Which periods are found in the Mesozoic Era?

Back

Triassic, Jurassic, Cretaceous.

Front

What are the four main eras of the geological timescale?

Back

Precambrian, Paleozoic, Mesozoic, Cenozoic.

Front

What significant event marks the end of the Paleozoic Era?

Back

The Permian-Triassic extinction event.

Front

What is the significance of the Cenozoic Era?

Back

It is known as the Age of Mammals.

Front

What major event occurred during the Mesozoic Era?

Back

The rise and fall of dinosaurs.

Front

What is a period in the geological timescale?

Back

A subdivision of an era, characterized by specific geological or biological events.