Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they...
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![Page 1: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/1.jpg)
Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart
Pangaea – the first super-continent
• Alfred Wegner 1912Presented early fossil evidence• No evidence to explain how or why continents moved• Continental Drift Theory later developed into the theory of Plate Tectonics
![Page 2: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/2.jpg)
Evidence supporting Continental Drifta) Continental Puzzle –
continents fit togetherb) Matching Fossils -
matching fossils (Mesosaurus) on cross ocean landmasses
c) Mountain chains and rock type – (Appalachian)
d) Ancient climates – (ice core data, scratched bedrock)
![Page 3: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/3.jpg)
Plate Tectonics TheoryEarth's outermost layer, the lithosphere, is broken into 7
large, rigid pieces called plates: the African, North American, South American, Eurasian, Australian, Antarctic, and Pacific plates. Several minor plates also exist, including the
Arabian, Nazca, and Philippines plates. • plates are moving ~ 5 cm per year in different directions and speeds• The place where the two plates meet is called a plate boundary•Plates are crust and upper mantle
![Page 4: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/4.jpg)
Plate Boundaries and Actions
•Seafloor spreading produces new lithosphere •San Andreas Fault is an example of a Transform Fault•East African Rift Valley is an example of a divergent plate boundary•Himalayas are an example of convergent continental/continental plates
![Page 5: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/5.jpg)
Evidence and Testing for Plate Tectonics• Paleomagnetism –
changing patterns of magnetized rocks
• Earthquake patterns – link between plate boundaries and earthquakes
• Ocean Drilling - age of seafloor sediment– Newest (ridge crests)– Oldest (continental
edges)• Hot Spots – show plates
move over Earth’s surface (Hawaii)
![Page 6: Continental Drift Hypothesis – Wegner believed continents had once been joined, and over time they drifted apart Pangaea – the first super-continent Alfred.](https://reader035.fdocuments.us/reader035/viewer/2022062304/56649d035503460f949d674b/html5/thumbnails/6.jpg)
Cause of Plate Motion (tectonics)
• Heat convection in the mantle is the basic cause of plate movement
• Slab Pull and Ridge Push – downward convective flow of lithosphere (plate boundaries)
• Mantle Plumes – upward convective flow (volcanoes, hot-spots)