Transcript Geologic Time Scale - Colorado Springs School District 11

The entire history of the world as told to us by the dirty,
filthy rocks
4.6 bya
Precambrian Time
Phanerozoic
Eon (the 3
Eras)
544 mya
Present
•4.6 bya -- begins when Earth forms from gas and dust (we think)
•4 bya – oceans form
•2.5 bya – organisms begin photosynthesis, makes more oxygen in the
atmosphere.
•Most organisms were bacteria, algae, or soft-bodied animals
Paleozoic Era
Explosion of life
245
mya
Mesozoic
Era
66.4
Cenozoic
mya
Era
Age of the dinosaurs
Rise of the
mammals
Present
544
mya
•Shallow seas cover much of the
land
•Explosion of life in seas
•Invertebrates with shells appear
Cambrian
544
mya
Ordovician
505
mya
•Ice cap covers North
America
•Early vertebrates –
jawless fish – become
common
•Coral reefs develop
•Land plants appear
•Insects & spiders
appear
Silurian
438
mya
•Winged insects
•First true reptiles
•N. America & Europe
are covered in swamps
Devonian Carboniferous Permian
408
mya
•Age of fishes begins
•First amphibians
•Forests grow in
swampy areas
360
mya
286
mya
•Pangaea forms
•Reptiles become dominant
•Mass extinction kills many
marine invertebrates
245
mya
Triassic
245
mya
Jurassic
208
mya
•Age of Reptiles begins
•First dinosaurs appear
•First mammals appear
•Turtles & crocodiles
appear
Cretaceous
144
mya
•Pangaea continues to break apart
•Sea levels rise
•Largest dinosaurs thrive
•First birds appears
•First flying reptiles appear
(pterosaurs)
66.4
mya
•Widespread volcanic
activity
•First flowering plants
appear
•Tyrannosaurus Rex
•Mass extinction kills
dinosaurs
66.4
mya
•Age of mammals begins
•Whales and dolphins appear
•Horses, elephants, bears, rodents, and
primates appear
•Continents move into present locations.
1.6
mya
•Thick glaciers advance in most of N.
America & Europe, all of Antarctica,
and parts of S. American and Asia.
•Giant mammals in N. America &
Eurasia
•Mr. Cruz is born – the people rejoice!
Present
Tertiary