Geologic Time Scale - Eons, Eras, Periods, Epochs

Eon

Largest unit of geologic time

Epoch

Smallest unit of geologic time

Phanerozoic

Most recent eon

Cenozoic

Most recent era

Quaternary

Most recent period

Holocene

Most recent epoch

Hadean

Oldest eon

Precambrian

Oldest era

Cambrian

Oldest period

4.6 bya

Date of earth’s creation

541 mya

Date of cambrian explosion

252 mya

Date of pangea formation

66 mya

Date of dinosaur extinction

2.6 mya

Start of ice age cycles

Middle life

Mesozoic means ________

Old life

Paleozoic means _______

Recent life

Cenozoic means

Cambrian, Ordovician, Silurian, Devonian, Mississippian, Pennsylvanian, Permian

Paleozoic periods in order

Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, Holocene

Cenozoic epochs in order

Cenozoic

Age of mammals

Mesozoic

Age of reptiles

Mississippian, Pennsylvanian, Permian

Age of amphibians

Silurian, Devonian

Age of fishes

Cambrian, Ordovician

Age of invertebrates

Early life

Proterozoic means ________

Triassic, Jurassic, Cretaceous

Mesozoic periods

Tertiary, Quaternary

Cenozoic periods

88

The Precambrian took up __% of earth’s history