seafloor spreading

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Seafloor Spreading

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Seafloor Spreading. Mapping of Ocean Floor. 40’s – 50’s use of echo sounding—using sound waves to map ocean floor to locate mountains and valleys. Mapping of Ocean Floor. Mid-ocean ridge – underwater mountain range. Theory of Seafloor Spreading. - PowerPoint PPT Presentation

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Page 1: Seafloor Spreading

Seafloor Spreading

Page 2: Seafloor Spreading

Mapping of Ocean Floor

• 40’s – 50’s use of echo sounding—using sound waves to map ocean floor to locate mountains and valleys

Page 3: Seafloor Spreading

Mapping of Ocean Floor

• Mid-ocean ridge – underwater mountain range

Page 4: Seafloor Spreading

Theory of Seafloor Spreading

• 60’s Harry Hess—hot dense material below Earth’s crust rises toward surface @ mid-ocean ridge then pushes seafloor apart –magma flows from cracks forming new floor

Page 5: Seafloor Spreading
Page 6: Seafloor Spreading

Evidence

• 68 Glomar Challenger—drilled holes in floor for rock samples

young rocks near ridge oldest farther away

Page 7: Seafloor Spreading

Evidence

• New organisms discovered by submersibles

Page 8: Seafloor Spreading

Evidence

• Magnetic Clues—magnetic lines reversed directions every 1000 to million years

Page 9: Seafloor Spreading

Evidence

• Magnetic Time Scale—Magnetite shows reversals in magnetic field

Page 10: Seafloor Spreading

Evidence

• Detected by magnetometer—showed new rock being formed at mid-ocean ridge & explained crust movement