Page 714 - Environment: The Science Behind the Stories

Geologic Time Scale e
APPENDIX

Eon Era Period
0 0 Neogene 2.6 Quaternary First humans
PHANEROZOIC CENOZOIC Paleogene 23 K-Pg mass extinction
Numerous glaciations

66
0.5 Rocky Mountains form
100
Cretaceous
MESOZOIC 145

1.0 Jurassic Atlantic Ocean opens
200
201 First dinosaurs, birds, mammals
Triassic
PROTEROZOIC 300 Supercontinent Pangaea
1.5 Millions of years ago Permian 252 Largest mass extinction

299
Carboniferous Coal-forming swamps
widespread
2.0 400 PALEOZOIC Devonian 359 Insects begin to diversify

Billions of years ago 2.5 Ordovician 419 First land plants

Silurian
443

500 485
Cambrian First vertebrates
Marine animals diversify
3.0 541
ARCHEAN First eukaryotes

3.5
Oxygen builds up
in atmosphere

Oldest evidence of life
4.0
Age of bombardment Geolo G i c Time Scale
HADEAN

4.5
Origin of Earth

E-1

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