1. A method for organizing Earth’s history
Geologic Time Scale
A method for organizing Earth’s history

2. What is time?

3. The Earth is 4.6 Billion years old…
That amount of time is hard to imagine…
With over 30 million seconds in a year, it would take 150 years to count 4.6 billion seconds on a clock!

4. To count to a billion, it would take 95
To count to a billion, it would take 95.1 years if you count a number every 3 seconds
To walk a billion steps, you would go around the equator times at 2 feet per step
To make a billion dollars, you would need to make $100 a day for 27, years

5. Historical Geology: A Glimpse of the Earth's Past. United Learning
Historical Geology: A Glimpse of the Earth's Past. United Learning unitedstreaming. 4 January 2007 <

6. The Geologic Time Scale
A system of dating Earth’s history by combining GEOLOGY with
BIOLOGICAL
EVENTS

7. The Geologic Time Scale uses : Relative Time
Based upon order of events
And
Absolute Time
Based upon numbers

8. Pre-Cambrian and Paleozoic Eras. AIMS Multimedia unitedstreaming. 4 January 2007 <

9. recognized by a feature (ex: Ice Age)
shortest chunk

10. Subdivisions of the periods Based on ROCK and FOSSIL evidence
2. Epoch
Short time spans
Subdivisions of the periods
Based on ROCK and FOSSIL evidence

11. Based on major geologic disturbances of Earth’s crust
3. Period
Shorter
Based on major geologic disturbances of Earth’s crust

12. Based on life characteristics; biologic events
4. Era
Broad
Based on life characteristics; biologic events

13. Two or more eras form an Eon Based upon the presence of visible life
Longest division
Two or more eras form an Eon
Based upon the presence of visible life

14. TLC Elementary School: Prehistoric Earth. Discovery Channel School
TLC Elementary School: Prehistoric Earth. Discovery Channel School unitedstreaming. 4 January 2007 <

15. Arranged chronologically
Oldest events at the bottom
Most recent events at the top

16. Looking at the Geologic time scale…
What are the eras in order from most recent to oldest?

17. Now… Read about your era on the geologic time scale
Complete the questions you have been assigned
Work on the timescale activity while you wait
Teach your era to your group
Get the notes for the other eras

18. Origin from Non-Living Matter Theory...
Life formed from non-living
matter after the Earth cooled.
4.0 Billion years ago, the surface cooled forming solid crust
H2O vapor condensed & fell as rain
Much CO2, H2, CH3, CO, SO2, and N gas
No oxygen or ozone
Energy from lightning and UV from the sun caused
Chemical reactions formed organic materials

19. Non-Living Matter Theory
Theory was tested by
Miller-Urey Experiment
Scientists recreated the conditions of the early Earth to show how materials of life could form from non-living materials
Henahan, Sean. From Primordial Soup to the Prebiotic Beach.. Access Excellence December 2002<

20. This apparatus re-created conditions on a young
Miller-Urey Experiment
This apparatus re-created conditions on a young
Earth, proving that complex molecules could have been created on early Earth

21. Precambrian Era 85% of Earth’s History!! Molten earth forms & Cools
NO free o2 gas in Atmosphere (very primitive)
Oceans form

22. hydrothermal ocean vents Nutrient rich
Life began
hydrothermal ocean vents
Nutrient rich
prokaryotes (bacteria-no nucleus)
Originally-life was prokaryotic; no nucleus; didn’t need oxygen
Meteorites continued hitting earth; brought more necessary nutrients and chemicals
At some time, the ocean was covered with ice so that protected the things that were forming in the oceans

23. Photosynthesis; O2 released
later cyanobacteria (stromatolites)
Photosynthesis; O2 released
Ozone created
Then, Eukaryotes (nucleus) and soft bodied multicellular organisms
Cyanobacteria is photosynthetic; blue-green algae
It releases o2 this is critical; o2 accumulates to o3 as it is bombarded with radiation and lightening and creates ozone layer
The ozone layer makes more substantial life possible b/c it protects from UV

24. Paleozoic Era ocean life expanded Life moved to land
Plants (except flowering)
Fungi
Insects
Reptiles
Mass extinction
Largest ever
90% organisms become extinct
Ocean life completely changes
TRILOBITES

25. Cambrian Explosion Numbers of marine species increased greatly
A relatively short time during
the Paleozoic Era
Diversity of living things increased dramatically
Most living species have ancestors from the Cambrian period
Video clip from: Historical Geology: A Glimpse of the Earth's Past. United Learning unitedstreaming. 6 January 2006 <

26. Burgess Shale Fossil location in Canadian Rocky Mountains
Fossils from the “Cambrian Explosion”
Area thought to have been
under water, near the equator
Special because of age & shape of fossils of ‘soft-bodied’ animals
Video clip from: Greatest Discoveries with Bill Nye: The Origin and Evolution of Life. Discovery Channel School unitedstreaming. 6 January 2006 <

27. Burgess Shale Why is the Burgess Shale so important?
What does the Burgess Shale provide evidence for?
Video clip from: Greatest Discoveries with Bill Nye: The Origin and Evolution of Life. Discovery Channel School unitedstreaming. 6 January 2006 <

28. Mesozoic Era dinosaurs marine lizards Birds Plants Conifers Flowers
Mass extinction
Dinosaurs
Many plants and animals

29. Mesozoic Era Triassic Period (225-180 MYA)
Pangaea (supercontinent) formed

30. Mesozoic Era Jurassic Period (180-135 MYA)
Pangaea starts to separate

31. Mesozoic Era Cretaceous Period (135-65 MYA)
Continents in modern positions

32. Mesozoic Era Cretaceous Period (135-65 MYA)
Mass Extinction: 50% of all plant and animal groups die out
Alvarez’s Meteor Impact Theory- 10 km wide meteorite hits Earth

33. How could a meteorite impact cause a mass extinction?
The impact caused shock waves, tidal waves, and sent a tremendous amount of dust into the atmosphere
As the dust re-entered the Earth’s atmosphere, it would have instantly heated the atmosphere causing tremendous forest fires
Dust from impact blocked out the sun and caused major climate change and plants to die
Plants, animals, etc. went extinct due to the climate changes and competition between organisms

34. Cenozoic Era mammals Primates humans Climate changes Ice ages
Caused migrations and extinctions
Geologic changes
Mountains
Volcanoes
civilization

35. The Great Ice Age

36. A Sixth Mass Extinction?
Are we the cause of a sixth mass extinction that is currently taking place?
Round Table Discussion