Timescale of Earth's Events 2-ESS1-1

Grade 2 - NGSS - CA

The largest unit of the geologic time scale, it is divided into eras, periods, and epochs

Eon

The largest unit of the geologic time scale, it is divided into eras, periods, and epochs. Eon It's a really long period of time when big things happen on Earth.

A unit of geologic time longer than an age but shorter than a period

Epoch

A unit of geologic time longer than an age but shorter than a period. Epoch. In simple terms for Grade 2, an epoch is a long time in Earth's history when something special happened, like the time when lots of dinosaurs lived.

The second-longest unit of geologic time, it is divided into periods

Era

The second-longest unit of geologic time, it is divided into periods. Era. An era is a long time in Earths history when big changes happened.

The change in a species over time

Evolution

The change in a species over time. Evolution. Evolution means living things change and adapt over many generations to fit their environment better.

A timeline of Earth's history based on major changes

Geologic time scale

A timeline of Earth's history based on major changes. Geologic time scale. The geologic time scale is a way to show Earth's history by dividing it into times when big changes happened.