Warm-up: Geologic Time Scale

Front

What is the Geologic Time Scale?

Back

A system of chronological dating that relates geological strata to time, used by geologists and other Earth scientists to describe the timing and relationships of events in Earth's history.

Front

What are the main divisions of the Geologic Time Scale?

Back

Eons, Eras, Periods, and Epochs.

Front

Which eon do we currently live in?

Back

The Phanerozoic Eon.

Front

What is the most recent era in the Geologic Time Scale?

Back

Cenozoic Era.

Front

What percentage of Earth's history is represented by the Precambrian Era?

Back

About 90%.

Front

What is the law of superposition?

Back

A principle stating that in undisturbed sedimentary rock layers, the oldest layers are at the bottom and the youngest are at the top.

Front

What is an epoch in the context of the Geologic Time Scale?

Back

A subdivision of a period in the Geologic Time Scale, representing a specific time frame in Earth's history.

Front

What is the difference between an era and a period?

Back

An era is a larger division of time than a period; periods are subdivisions of eras.

Front

Name the four main eons of the Geologic Time Scale in order.

Back

Hadean, Archean, Proterozoic, Phanerozoic.

Front

What significant events mark the beginning of the Phanerozoic Eon?

Back

The appearance of abundant fossil evidence and the Cambrian Explosion.