1. Plate Tectonics
Continental Drift

2. Plate Tectonics
Chapter 17

3. Early Ideas Abraham Ortelius Eduard Suess Alfred Wegener
Late 1500’s Dutch mapmaker
Noticed N & S America seemed to fit with Europe & Africa
Thought they were separated by quakes & floods
Eduard Suess
Late 1800’s Australian geologist
Proposed Gondwanaland
All southern continents were once joined
Alfred Wegener
Early 1900’s German scientist
Proposed Continental Drift hypothesis

4. Continental Drift Proposed by Wegener in 1912
Stated that all Earth’s continents were once joined in a single landmass called Pangaea
pan → all gaea → Earth
Continents broke apart 200 mya and moved to present position

6. Evidences of Continental Drift
Jigsaw fit of continents
Rock formations
Similar rock structures & types on separate continents
Mountain ranges
Coal deposits
Fossils
Same species on different continents with different climates, separated by salt water
Climate evidence
Coal deposits: form in temperate swamps, now in Antarctica
Glacial deposits in tropical areas (no glaciers there now)

7. Jigsaw Fit

8. Rock Evidence

10. Climate Evidence

11. Why was Wegener’s hypothesis not accepted?
Too many unanswered questions
What caused continents to move? Earth’s rotation, maybe? Proved NO
How could continents push through ocean floor? Wouldn’t this cause fractures? None found then.
Hypothesis thrown out by most until 1960’s