1. Organized into divisions based on major changes
Geologic Time- A method of looking back at earth’s history based on the information preserved in the fossils and other rock structures of the rock record.
Geologic Time Scale- A summary table of the geologic history of the earth.
Organized into divisions
based on major changes
or events that took place
4 Eras
15 Periods D
Tertiary

2. G E O L I C T M S A
Tertiary

3. ERA- largest time division, oldest at bottom, most recent at top
32) Cenozoic 25) Mesozoic 9) Paleozoic 2) Precambrian

4. 3)Hadean : 4.6 BYA-3.8 BYA -Solar System started to form
-Protoplanet formed
-Solar System started
to form

5. 5)Archean 3.8BYA – 2.5BYA -minerals form -oceans form
-planet cooling
-minerals form
-oceans form
-1st life (bacteria & stromatolites- in oceans)
-Cratons form –(original continent- most ancient rocks)

6. 7)Proterozoic : 2.5 BYA-540 MYA
-Large amount of SIMPLE LIFE
-only in ocean; worms, jellyfish, bacteria

7. 10)Cambrian 540- 500 MYA -Trilobites thrive -Brachiopods numerous
-1st vertebrates seen
(backbone)

8. 12)Ordovician 500- 430 MYA -Appalachian Mountains form
-Jawless fish seen

9. 14)Silurian : 430 - 400 MYA -1st jawed fish -1st land animals
-1st plants
-1st jawed fish
-1st land animals

10. 16)Devonian 400- 345 MYA Air breathing fish 1st amphibians Insects
Bony Fish
                                                                                                      

11. 18)Mississippian MYA
-Ferns thrive
-Amphibians common

12. 20)Pennsylvanian- 325-280 MYA -coal forming swamps
-1st reptiles
-coal forming swamps
-location of coal today

13. 22) Carboniferous

14. 23)Permian: MYA
-mammal-like reptile
-mass extinctions

15. 26)Triassic : 250-190 MYA -volcanoes on east coast of N.A.
-1st dinosaurs
-volcanoes on east coast of N.A.
-Conifer trees
-1st mammals

16. 28)Jurassic : MYA
-1st birds
-Dinosaurs
dominate

17. 30)Cretaceous: 135-65 MYA -1st flowers - Bees -dinosaurs become
extinct
-Rocky
Mtns
form

18. 33)Tertiary : 65-1.5 MYA Mammals thrive 1st human-like creatures seen
(hominids)

19. Quaternary: 1.5 MY- Present
-Modern people
-Civilization
-Cities