Earth Science

The second broadest category of geologic time is______________?. The Cenozoic is one of them.

• era

• eon

• epoch

• period

Earth is thought to be formed ______ years ago?

• 200 thousand

• 4.6 billion

• 3 million

• 13.8 billion

Describes a group of living things that are no longer living.

• fossil

• endangered

• extinct

• dinosaur

The geologic time scale is divided into four large units known as

• Eras

• Periods

• Eons

• Units

In which eon do we know there was no life?

• Carboniferous

• Hadean

• Miocene

• Tithonian

What is an eon?

•  Long span of geologic time. In formal usage, the longest portions of geologic time.

• the basic unit of the geologic time scale; during these spans of time specific systems of rocks were formed.

• very long span of geologic time; in formal usage, the second longest portions of geological time.

• Unit of geological time during which a rock series is deposited.

What is an era?

• Long span of geologic time. In formal usage, the longest portions of geologic time.

• the basic unit of the geologic time scale; during these spans of time specific systems of rocks were formed.

• very long span of geologic time; in formal usage, the second longest portions of geological time.

• Unit of geological time during which a rock series is deposited.

When did the formation of the moon occur?

• Hadean

• Archean

When did the formation of the earth occur?

• Hadean

• Archean

When was the first ocean formed?

• Hadean

• Archean