Geologic Time Flashcards

Flashcards reviewing geologic time units and major events in Earth's history.

Eon

The largest division of geologic time.

Era

A major division of geologic time, smaller than an eon but larger than a period.

Period

A division of geologic time, smaller than an era but larger than an epoch.

Epoch

The smallest division of geologic time.

Hadean Eon

The first eon of the Precambrian Supereon.

Archean Eon

The second eon of the Precambrian Supereon.

Proterozoic Eon

The third eon of the Precambrian Supereon.

Paleozoic Era

The first era of the Phanerozoic Eon.

Mesozoic Era

The second era of the Phanerozoic Eon.

Cenozoic Era

The third era of the Phanerozoic Eon.

Theia Impact

A massive collision during the Hadean Eon that contributed to the Earth was uninhabitable.

Prokaryotes

The first life that originated in the Archean Eon.

Eukaryotes

Single celled or multicellular organism with a nucleus that originated in the Precambrian Supereon

Rodinia

A supercontinent that assembled during the Precambrian.

Great Oxidation Event

A significant increase in atmospheric oxygen during the Proterozoic Eon, around 2.4 billion years ago.

Cambrian Explosion

A rapid diversification of life that occurred approximately 541 million years ago.

Pangaea

A supercontinent that formed in the late Paleozoic and broke up in the Mesozoic.

Permian-Triassic extinction

Mass Extinction event around 252 million years ago.

Cretaceous-Tertiary extinction

Mass Extinction event around 66 million years ago wiped out the dinosaurs.