1. Earth History and The Fossil Record

3. Aim: What were the major geologic developments during Earth’s history?
Do Now: Does anyone know how old the Earth really is? How do you think we know?

4. Precambrian Earth Earth formed about 4.56 billion years ago
During this time
The atmosphere and oceans formed
Plate tectonics began to build landmasses

5. Earth Formation Gravity pulls together dust, rock, and ice from space
High-velocity rocks from space cause the planet to melt

6. Earth Formation (cont.)
Dense materials (Iron/Nickel) sink to the center forming the core

7. Earth Formation (cont.)
Less dense materials (silicates) “floated” forming earth’s mantle and crust

8. Atmosphere Formation Earth’s early atmosphere consisted of:
Water vapor
Carbon dioxide
Nitrogen
Several trace gases
NO OXYGEN

9. Ocean Formation Water vapor in the air starts to cool and condense
Condensed water vapor turns to liquid and forms the early oceans

10. Earth’s Time Scale ESRT Page 8 AND 9
Earth’s time has been broken up into SPECIFIC time units

11. Earth’s Time Scale (USE YOUR ESRT!)
Largest Length of Time
Smallest Length of Time
Time Scale
EONS
ERAS
PERIODS
EPOCHS

12. EONS
Phanerozoic
Pre-Cambrian
Archean
Proterozoic

13. ERAS
Cenozoic
Mesozoic
Paleozoic

14. PERIODS PALEOZOIC ERA Broken into: Permian Carboniferous Devonian
Silurian
Ordovician
Cambrian

15. PERIODS
MESOZOIC
Broken into:
Triassic
Jurassic
Cretaceous

16. PERIODS
CENOZOIC
Broken into:
Quaternary
Neogene
Paleogene

17. EPOCHS Smallest Time Scale Broken into: Early/Middle/Late
Or the “CENES”
Holocene
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
Paleocene

22. Radioactive Dating