Lesson #2 - Geological Time Scale

Geologic time

This is the immense span of time covering Earth’s history.

4.6 billion

Earth formed approximately _____ years ago.

Geological Time Scale

This is a system used to organize Earth’s history into major intervals based on significant geological and biological events.

Eon, Era, Period, Epoch

The hierarchy of geologic time, from largest to smallest divisions is:

Eon

This is the largest division of geologic time in Earth’s history.

Hadean, Archean, Proterozoic, Phanerozoic

The 4 eons in Earth’s history are called:

Hadean Eon

This is the eon where earth was extremely hot, with a largely molten surface.

Archean Eon

This is the eon where early continents developed, and some of the earliest known life forms appeared.

Proterozoic Eon

This is the eon where oxygen accumulated in the atmosphere.

Phanerozoic Eon

This is the eon where complex life became abundant.

Paleozoic, Mesozoic, Cenozoic

What are the three major eras in the Phanerozoic Eon?

Paleozoic era

This is the era that is characterized by the diversification of marine organisms and the movement of plants and animals onto land.