1. Plate Tectonics
ESPS 2015
Hagen

2. ESSENTIAL QUESTIONS Explain and give evidence of Continental Drift
Describe the process of sea-floor spreading
List and analyze the 3 types of boundaries

3. SPONGE ACTIVITY Give one piece of scientific evidence that is true
and one piece that is false

4. Why do Continents Drift?
Earths crust is not a uniform covering, its made of 8 major and minor plates – North American/Pacific/Juan de Fuca plate
As these plates move, the continents are rafted along passively (like a piggyback ride on top of Aesthenosphere, which is on top of the mantle
1960’s the Theory of Continental Drift or Plate tectonics became established

5. Continental Drift 1900’s-----1912
Alfred Wegener first proposed the theory of continental drift. Wegener provided evidence that the there was once a giant land mass, but did not explain how the continents moved
His theory stated that the continents used to be one large super-continent or “Pangea” and through time they have broken apart and moved.

6. Continental Drift
Wegener hypothesized that there was a gigantic supercontinent 200 million years ago, which he named Pangaea, meaning "All-earth".
EVIDENCE!!!!!! Give some space below each type of evidence
Continental Fit – Example of South America and Africa.
2. Fossils – Fossils in S. America and Africa Dated the same
Glacial Patterns – Glacial scars on N. America and Asia/Europe that had the same dates

7. Continental Drift Evidence:
When you look at a map you can see the how the edges of continents fit together like a puzzle
The theory of continental drift states that continents have moved from their current locations and will continue to move over time
Tectonic plates move with speed ~1 cm/year to ~10 cm/year.
The speed is different from plate to plate, and can depend on how much active the plate currently is.
Continental Fit

8. Continental Drift Evidence
FOSSILS EVIDENCE
Fossils show that the same reptiles lived on different continents despite being so far apart. Plants too.

9. Continental Drift Evidence
Glacial Patterns
and Rock Clues
Geological features show that colder climates were once warmer and warmer climates were once cold (e.g. glaciers and plant fossils)
Rock clues show the same rock features on different continents

10. Cut out continents and then paste them on the map
Evidence Activity
Cut out continents and then
paste them on the map
Be sure to match up fossil
evidence with rock and desert
evidence

11. Homework tonight
Case of the Mesosaurus

12. Continents today

13. Seafloor Spreading
At one time the bottom of the ocean was a foreign as space; with the discover of using sound waves to map the ocean floor lead to amazing discoveries
A system of ridges and valleys was discovered running through the center of the Atlantic Ocean
Sea floor spreading is the process by which new sea floor is created, pushing two tectonic plates further apart

14. Seafloor Spreading
As scientists began studying the ages of the ridge they found that as they moved towards the center of the ridge the rocks got younger and younger
This means that new rock was forming at the center of the ridge and being pushed outwards as new rock filled in

15. Seafloor Spreading Evidence of Seafloor spreading:
The rocks age as they move away from the ridge
The new rock contains iron which is magnetic; over the course of the Earth’s history the magnetic poles have switched; when the iron in the rock cools it lines up with the pole; the iron samples have reversed several times

16. Theory of Plate Tectonics
With the discovery of seafloor spreading showed more than why the continents are the way they are – they showed why we have the geological features that we do
The Theory of Plate Tectonics combines continental drift and seafloor spreading and states that there are several plates that move around the mantle of the Earth

17. Theory of Plate Tectonics
Where two plates interact are called plate boundaries
3 types of boundaries are called divergent, convergent and transform
These boundaries form earthquakes and volcanoes
Divergent boundaries move apart and cause seafloor spreading

18. Theory of Plate Tectonics
Convergent boundaries move together and form volcanoes
Ocean – ocean boundaries (hot spots)
Ocean – continental boundaries (magma chambers)
Continental – continental boundaries (mountains)
Transform boundaries move past one another and form earthquakes

19. Theory of Plate Tectonics