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Theory of Continental Drift. Cornell Notes Pg. 93. The Theory of Continental Drift. Alfred Wegener (1910) Formed a hypothesis that all the continents were once joined together and have drifted apart. What was Wegener’s evidence?. Evidence from: Landforms —the continents fit together
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Theory of Continental Drift Cornell Notes Pg. 93
The Theory of Continental Drift Alfred Wegener (1910) Formed a hypothesis that all the continents were once joined together and have drifted apart
What was Wegener’s evidence? • Evidence from: • Landforms—the continents fit together • Fossils—ancient plants and animals found in many different continents • Climate—Antarctica has plant fossils. Tropics have rocks with ice scratches from glaciers- “glacial scarring” • Rock Types- similar rocks found where continents may have once been joined together.
Pangaea • Continents were joined together in one land mass • “The super continent” 245 mya
Sea Floor Spreading Harry Hess (1960) as the ocean floor spreads apart, new crust material rises from the mantle and creates new sea floor to fill the “hole.”
HESS (1960) • Sea floorspreading • Continents were moving (as Wegener had proposed) • Evidence 1. 2. 3.
1. The discovery of the Mid-ocean Ridge • Scientists mapped 47,000 miles of underwater volcanic ridges by using sonar
3. Ocean floor samples—older crust is further away from ridges