Continental Drift Theory Flashcards
Plate Tectonics is a synthesis of what two theories?
- Continental Drift Theory by Alfred Wegener
- Seafloor Spreading by Harry Hess and Robert Dietz
Continental Drift Theory Maker
Alfred Wegener (1912), meteorologist
Seafloor Spreading Makers
Harry Hess (Princeton) and Robert Dietz (Marine Coastal Geodetic)
Types of Plate boundaries
- Converging
- Divergent
- Transform (passive)
Evidence 1 of Continental Drift Theory
Continental Fit: From Pangaea came Gondwanaland (South America and Africa) and Laurasia (North America, Europe, and Asia)
All continents in Pangaea
South & North America, Africa, Eurasia, Antarctica, Australia, and India
What is the Flaw of the Continental Drift Theory?
Wegener did not fully understand what causes the plates to move
What causes the plates to move
The mantle’s convection currents acts like a conveyor belt and it causes the plates to slide
What is Evidence 2 of Continental Drift Theory?
Distribution of Fossils
Explanation of Distribution of Fossils
Fossils of (Glosopteris, Lystrosaurus, and Mezosaurus) are found in unexpected far continents
Explain Glosopteris
- Fern-like plant
- seeds are too large to be airborne for long distances
- Found in Southern America Southern Africa, India, Antarctica, Australia
Explain Lystrosaurus
- strictly land-dwelling reptiles
- Found in Africa Antarctica, and India
Explain Evidence 3 of Continental Drift Theory: Match of Rock Ages and Structure
- Match of Mountain belts (Appalachian mountains matching with Ireland, Scotland, and Norway rocks)
- Match applicable only to rocks older than Cretaceous
Explain Mesozaurus
- freshwater reptile
- found in Brazil and Africa
Explain Evidence 4: Stratigraphy of the Continental Drift Theory
- similar rocks suggest similar environment of deposition
Explain Evidence 5: Paleoclimate Indicators (CFE)
- Coal deposits found in Antarctica
- Fossil Coral reefs found in North America and Eurasia
- Evaporite deposits (salt)
Explain Evidence 6: Glaciation
- Glacial deposits (tillites) in S.A., Afr, India, Aus.
- Glacial striations: grooves made by motion of ice - points toward the ocean (“point of origin”)
Explain Evidence 7: Apparent Polar Wandering Curves
Assumption: There is always a magnetic north at any given time
Fixed Continent, Poles Wander vs. Drifting Continent, Fixed Pole
Impacts of the Continental Theory
- Continents are capable of lateral motion
- Challenged the notion of largely up and down motion
- Challenged the idea of permanence
Inspiration of CDT
Drifting icebergs
Why was CDT met with skepticism?
Wegener didn’t provide a convincing driving mechanism for the plates to move - would later be supported by Seafloor Spreading
