the time of the physical formation and development of the earth (especially prior to human history)

the period from about 540 million years ago until the present, a period when abundant life existed

the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago

from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms

the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life

the earliest eon in the history of the Earth from the first accretion of planetary material (around 4,600 million years ago) until the date of the oldest known rocks (about 3,800 million years ago); no evidence of life

of or relating to a geological eon (longer than an era)

of or relating to a geological eon (longer than an era)

a major division of geological time; an era is usually divided into two or more periods

of or relating to a geological eon (longer than an era)

the period from about 540 million years ago until the present, a period when abundant life existed

the eon following the Hadean time and preceding the Phanerozoic eon; from about 3,800 million years ago until 544 million years ago

from 2,500 to 544 million years ago; bacteria and fungi; primitive multicellular organisms

the time from 3,800 million years to 2,500 million years ago; earth's crust formed; unicellular organisms are earliest forms of life

the earliest eon in the history of the Earth from the first accretion of planetary material (around 4,600 million years ago) until the date of the oldest known rocks (about 3,800 million years ago); no evidence of life

a major division of geological time; an era is usually divided into two or more periods