Geologic Time Scale Review

Front

What is the geological time scale?

Back

A time line dividing the Earth’s history into units representing millions of years.

Front

Which is the youngest rock layer?

Back

Mudstone

Front

What is absolute age dating?

Back

The number of years since the rock was formed.

Front

What are fossils?

Back

Preserved remains of plants and animals from the remote past.

Front

What is an invertebrate?

Back

An animal that doesn’t have a backbone.

Front

What is a vertebrate?

Back

An animal that has a backbone.

Front

What are sedimentary rocks?

Back

Rocks formed by the accumulation of sediment.

Front

What is relative age dating?

Back

Determining the age of a fossil compared to the ages of other fossils.

Front

What is the significance of the Cambrian period?

Back

It marks a time when many major groups of animals first appeared in the fossil record.

Front

What is a mass extinction?

Back

A rapid decrease in the biodiversity on Earth.