What is the primary purpose of the geologic time scale?

To predict future asteroid impacts on Earth.

To document the history of all human civilizations.

To find the precise monetary value of different fossils.

What defines a distinct geologic period, such as the Carboniferous period?

The name of the scientist who first studied rocks from that time.

Its characteristic climate and the unique types of life that existed.

Its specific length of time, which is always the same for every period.

The first appearance of human ancestors in the fossil record.

It covers a vastly longer span of time.

It is measured exclusively in days and weeks.

It focuses only on events that occurred in the ocean.

It was created by historians rather than scientists.

The plant lived during the Carboniferous period.

The plant was likely the primary food source for all dinosaurs.

The climate of the Carboniferous period was identical to today's climate in Brazil.

This specific plant species could only grow in exactly two locations on the entire planet.