1 / 12

Understanding Sea-Floor Spreading: The Mid-Ocean Ridge and Its Geological Significance

The Mid-Ocean Ridge, the world's longest mountain chain stretching 50,000 km, mainly submerged underwater, plays a crucial role in shaping oceanic crust. Harry Hess proposed in 1960 that the ocean floor acts like conveyor belts, transporting continents as molten material from the mantle erupts at the ridge. This process, known as sea-floor spreading, continually adds new material to the ocean floor, supported by evidence like pillow-shaped rocks, magnetic stripes, and drilling samples. Subduction at deep-ocean trenches further explains ocean floor expansion and recycling back into the mantle.

wylie-keith
Download Presentation

Understanding Sea-Floor Spreading: The Mid-Ocean Ridge and Its Geological Significance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Sea Floor Spreading p. 331-337

  2. Mid-Ocean Ridge • Longest chain of mountains in the world (50,000 km long!) • Mostly underwater • Iceland part of Mid-Ocean Ridge • We use sonar to map the ocean floor

  3. How was the Ridge Made? • Harry Hess, studied the mid-ocean ridge • 1960 he suggested ocean floor like conveyor belts, carrying continents with them • Movement begins at mid-ocean ridge

  4. At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge. What Happens?

  5. Sea-Floor Spreading • Sea-floor spreading: the process that continually adds new material to the ocean floor. • Evidence for Sea-floor spreading: • Molten material • Magnetic stripes • Drilling samples

  6. Evidence: Molten Material • Rocks shaped like pillows found – only forms when molten material hardens quickly Scientists inside Alvin 4 km deep

  7. Evidence: Magnetic Stripes • Magnetic field around Earth • Poles have reversed themselves (last time 780,000 years ago) • Magnetized “stripes” on ocean floor hold record of reversed poles

  8. Evidence: Drilling Samples • Rocks drilled from ocean floor • Age of rocks determined • Further away from ridge, older the rock • Youngest rock found in the center of the ridge

  9. Subduction at Deep-Ocean Trenches • How can the ocean floor keep getting wider and wider? • Floor plunges into deep underwater canyons called deep-ocean trenches • These occur where oceanic crust bends downward

  10. Subduction is the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

More Related