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Sea Floor Spreading.

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Presentation on theme: "Sea Floor Spreading."— Presentation transcript:

1 Sea Floor Spreading

2 HDWK Mid Ocean Ridges Molten Material (go look! Pillow Lava!)
Detected a long time ago Molten Material (go look! Pillow Lava!) Magnetic Stripes Drilling Samples Subduction and Deep Ocean Trenches

3 Mid Ocean Ridges


5 Mid-Atlantic Ridge Pingvellir, Iceland

6 Iceland is ripping apart – but it gets filled in with new lava – so it gets bigger!

7 Africa is tearing apart too

8 How Convection helps Sea Floor Spreading (traditional version)

9 Go Look for Volcanic Activity!
Pillow lava from the Mid-Atlantic Ridge Shows active eruptions Sonar of a volcano & pillows

10 Magnetic Stripes – Reversals

11 Drilling the Sea Floor for Rock Ages

12 Glomar Challenger Drilling for Rocks (and used for other things! but we’d have to kill you if we told you what it was for )

13 Can it Spread Forever?? No Way, It has to go somewhere, and usually it dives under a continent! Oceanic Crust is Denser than Continental Crust – so it sinks under the continent. This process is called Subduction and makes the Deep Ocean Trenches

14 Subduction and Deep Ocean Trenches

15 More Detail than you want! Subduction!

16 Some Vocab Plate Convergent Plate Boundary Divergent Plate Boundary
Transform Plate Boundary Sea Floor Spreading Magnetic Reversal Rift Zone Subduction Island Arc


18 Hawaii is Special Hawaii is special, it is on the Pacific Plate, but the hotspot under the Big Island appears to have been there for 70+ million years. The evidence is the chain of islands stretching out to the NW from Hawaii to Kure – and on along the Emperor Seamount chain.

19 Kea and Loa


21 Tectonic Plates - names

22 Most of the volcanoes are located on or near ___________________
_________ volcano is the only one in the middle of a ___________.





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