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Sea-floor Spreading

Sea-floor Spreading. Mid- ocean ridge- Undersea mountain chain where new ocean floor is produced. Alfred Wegener. Harry Hess. Harry Hess - came up with the theory of sea-floor spreading .

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Sea-floor Spreading

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  1. Sea-floor Spreading • Mid-ocean ridge- Undersea mountain chain where new ocean floor is produced.

  2. Alfred Wegener Harry Hess • Harry Hess- came up with the theory of sea-floor spreading. • Sea-floor spreading- at the mid-ocean ridge, magma rises from the mantle and erupts. The magma spreads out, pushing older rock to both sides of the ridge.

  3. Picture of Sea-Floor Spreading

  4. Evidence for sea-floor spreading: • 1. Molten material- presence of rocks that can only form when molten material hardens quickly after erupting under water. (Pillow Lava)

  5. 2. Evidence from magnetic stripes in the rock of the ocean floor.

  6. 3. Drilling Samples- Glomar Challenger (drilling ship) brought up rock samples from the ocean floor and found that the farther away from the ridge the samples were taken, the older the rocks were. Youngest rocks were in the center of the ridges.

  7. Subduction at Deep-Ocean Trenches: • Deep-ocean trench- deep underwater canyons where old ocean floor eventually sinks. • Subduction- process by which the ocean floor sinks beneath a trench and back into the mantle.

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