1. Continental Drift

2. Pangaea Pangaea Theory of Continental Drift
All the continents were once part of a supercontinent.
Suggest that continents are in constant motion on the surface of the earth.

3. Evidence That Continents Move
Glaciers
Glaciers form in a climate that is below freezing most of the time.
Grooves in glaciers show that neighboring continents were once part of pangaea.

4. Evidence That Continents Move
Fossils
Rocks
Fossils of similar animals were found on several different continents.
Similar rock formations were found on different continents.

5. What was Missing? Wegener’s Hypothesis
Despite the evidence from glaciers, fossils, and rocks, he could not explain how such large pieces of land could move.

6. Continental Drift Hyposthesis
Coastline Fit
Rocks
Fossil Evidence
Climate Evidence

8. August 26, 2014 Warm UP What is the Continental Drift Hypothesis?
The theory that the continents are in constant motion.

9. August 27, 2014 Warm Up
Which two mountain ranges did Wegener use to support his idea that North America and Europe were once joined?
The Appalachian and the Caledonians.

10. Agree or Disagree? Why The seafloor is flat.
Echo sounding led to the discovery that the seafloor is not flat. Scientists discovered mountain ranges in the middle of the ocean, called mid-ocean ridges.

11. August 28, 2014 Warm Up
What device do scientist use to determine how deep the ocean is at any given place? How does this device work?
Scientists use echo sounders. The echo sounder sends out sound waves that bounce off the ocean floor.

12. Sept 2, 2014 Warm Up
Name four types of evidence scientists use to support the theory of seafloor spreading.
The four lines of evidence to support seafloor spreading are 1) parallel magnetic stripes, 2) changes in thermal energy, 3) sediment age, and (4) sediment thickness.

13. Sept 3, 2014 Warm Up How do continents move over the Earth’s surface?
Like groceries on a conveyor belt continents are carried along as the seafloor spreads away from a mid-ocean ridge.

14. Sept 4, 2014 Warm Up
Is Earth’s magnetic field currently normal or reversed polarity?
The Earth’s magnetic field currently has normal polarity.

15. Sept 5, 2014 Warm Up
How do magnetic minerals help support the theory of sea-floor spreading?
Magnetic minerals record the polarity of Earth’s magnetic field at the time of cooling and crystallization.