Geologic Timescale

Front

What is the Geologic Timescale?

Back

A system used by geologists and other Earth scientists to describe the timing and relationships of events in Earth's history.

Front

What are the four main Eras of the Geologic Timescale in order from oldest to most recent?

Back

Precambrian, Paleozoic, Mesozoic, Cenozoic.

Front

Which Era is known for the dominance of dinosaurs?

Back

Mesozoic Era.

Front

What is the most recent Era in the Geologic Timescale?

Back

Cenozoic Era.

Front

What is the oldest known organism on the Geologic Timescale?

Back

Trilobites.

Front

What does the term 'Eon' refer to in the Geologic Timescale?

Back

The largest division of geological time, which is made up of Eras.

Front

What Eon is known for visible life?

Back

Phanerozoic Eon.

Front

What is the significance of the Precambrian Era?

Back

It is the longest Era, covering about 88% of Earth's history, before complex life forms appeared.

Front

What major event marks the beginning of the Paleozoic Era?

Back

The Cambrian Explosion, which saw a rapid increase in the diversity of life.

Front

What are the three periods of the Mesozoic Era?

Back

Triassic, Jurassic, and Cretaceous.