1. GEOLOGIC ERAS AND PLATE TECTONICS

2. Planet Earth
Geologic History
Earth’s Interior
Tectonic Plates

3. Geologic History Precambrian Era 4.6 billion years ago until
570 million years
Volcanic Mountains
1) Mountain building
2) erosion
Fault
Ancient Sea
magma 
Igneous Rock
Ancient Sea
Sediments 
Original Canadian Shield
First single and multi-celled organisms

4. Geologic History Paleozoic Era 543 to 248 Million Years Ago
3) Sedimentary Rock
Folding/uplift
1) No Mountains
2) Sedimentary
Rock uplift
Erosion
Appalachian Mountains
Interior Plains
Very Old
Sediments
Igneous Rock
Sediments
 Lower layers changed into rock
NA covered by shallow seas
Appalachians formed
1st plants and animals appear on land

5. Geologic History Mesozoic Era 248 to 65 Million Years Ago Igneous Rock
4) Interior Plains
“folding young”
“old eroded”
5) GLSLL
3) Western Cordillera
2) Appalachian
MTNS
1) CDN Shield
oil
Igneous Rock
Formation of Rocky Mountains Begins
Reptiles and Dinosaurs
1st birds and mammals
Mountains Forming

6. Geologic History Cenozoic Era 65 million years to present (US!)
5) WESTERN CORDILLERA
3) APPALACHIAN
4) INTERIOR PLAINS
Coastal
Mountains
Rockies
1) CANADIAN SHIELD
2) GLSLL
Mountains Forming
ATLANTIC OCEAN
Heat
Volcanic Activity
Igneous Rock
Ice sheets cover most of NA
Continents take on present shape
Modern forms of life evolve

7. Earth’s Interior HYDROSPHERE ATMOSPHERE Crust - 8-64 km thick
Air
ATMOSPHERE
Water
Crust
km thick
- cold & fragile
- Granite and Basalt
Land
LITHOSPHERE
Mantle
km thick
- hot & molten
- Magnesium and Silicon
Outer Core
km thick °C
- liquid Nickel and Iron
Inner Core
km thick °C
- solid Nickel and Iron

8. Plate Tectonics - Continental Drift

9. Plate Tectonics - Continental Drift

10. Plate Tectonics - Continental Drift
THE CONTINENTS TODAY
Antarctica

11. HMMMM
Close examination of a globe often results in the observation that most of the continents seem to fit together like a puzzle: the west African coastline seems to snuggle nicely into the east coast of South America and the Caribbean sea; and a similar fit appears across the Pacific.

12. PANGAEA 1912 Alfred Wegener (1880-1930)
proposed that the continents were once compressed into a single large continent which he called Pangaea (meaning "all lands"),
believed that Pangaea was intact until about 300 million years ago, when it began to break up and drift apart.

13. FOUR MAIN PIECES OF EVIDENCE1.
Wegener noted the jigsaw fit of South America and Africa, especially, but also elsewhere

14. PROOF CONTINUED
2. He found fossils that were the same on both continents. After a certain period, the fossils begin to evolve differently on the different continents.

15. 3. He found that on both sides of the Atlantic, mountains were the same both in terms of age and structure.

16. 4. He found that ice sheets covered parts of Africa, India, Australia and South America 250 million years ago. How could this happen in places that are so warm today?

17. PROBLEM
Wegener's hypothesis of continental drift did NOT explain how the continents could drift across the earth's surface.
….thus, the theory of PLATE TECTONICS! NOT until the the 1960s
Earth’s outer shell made up of 20 plates
They move over a weak layer of hot rock which flows like slow-moving plastic
Unequal distribution of heat within the earth causes convection currents to move the plates

18. Plate Tectonics Map

19. PLATE TECTONICS THERE ARE THREE BASIC PLATE MOVEMENTS 1. DIVERGENT
where the plates move apart
new magma wells up to the surface forming new crust
the Mid-Atlantic ridge is a prime example.

20. MID-ATLANTIC RIDGE

21. 2. CONVERGENT two plates come together
one plate subducts (goes under) the other plate, creating a subduction zone
the crust at the leading edge of the subducting plate melts back into the mantle
3 different types of convergent boundaries

22. MID-OCEANIC CONVERGENCE

23. B. Convergence Zone: Oceanic Crust and Continental Crust

24. CONTINENTAL-CONTINENTAL

25. Accumulated material melts as it goes down into the mantle.
Rises back up as liquid rock.
Creates volcanoes and volcanic islands

27. 3. TRANSFORM BOUNDARIES two plates slide past each other
this can create tremendous friction, which may be eventually released in the form of violent earthquakes
the San Andreas Fault is a transform boundary

28. SAN ANDREAS FAULT CALIFORNIA

29. Plate Tectonics Sliding

30. Plate Tectonics Sliding
Less than Generally not felt, but recorded.
Often felt, but rarely causes damage.
Under At most slight damage to well-designed buildings.
Can be destructive in areas up to about kilometers across.
Major earthquake. Can cause serious damage over larger areas.
8 or greater Great earthquake. Can cause serious damage in areas several hundred kilometers across.

31. Tectonic setting of western British Columbia and Washington state
Tectonic setting of western British Columbia and Washington state. The oceanic Juan de Fuca plate is moving beneath the continental North America plate at a rate of about 4 cm/year. Earthquakes occur along parts of the boundary between the two plates.

32. This map, which shows 20th-century earthquakes in red, illustrates how they cluster on the edges of the major tectonic plates (outlined in yellow).

33. SUMMARY
Theory of continental drift and evidence to support it. (Pangea!)
Plate tectonics: how plates move (convection currents)
Different movements of plates, geologic processes and associated landforms
Diverging: ridges/volcanoes
Converging: trenches, mountains, island arcs
Subducting: same as above
Slipping/Transform: faults and earthquakes
Earthquakes and Volcanoes: along major tectonic plate boundaries