Presentation on theme: "HDWK Mid Ocean Ridges –Detected a long time ago Molten Material (go look! Pillow Lava!) Magnetic Stripes Drilling Samples Subduction and Deep Ocean Trenches."— Presentation transcript:
HDWK Mid Ocean Ridges –Detected a long time ago Molten Material (go look! Pillow Lava!) Magnetic Stripes Drilling Samples Subduction and Deep Ocean Trenches
Mid Ocean Ridges
Mid-Atlantic Ridge Pingvellir, Iceland
Iceland is ripping apart – but it gets filled in with new lava – so it gets bigger!
Africa is tearing apart too
How Convection helps Sea Floor Spreading (traditional version)
Go Look for Volcanic Activity! Pillow lava from the Mid-Atlantic Ridge Shows active eruptions Sonar of a volcano & pillows
Magnetic Stripes – Reversals
Drilling the Sea Floor for Rock Ages
Glomar Challenger Drilling for Rocks (and used for other things! but wed have to kill you if we told you what it was for )
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. Subduction Deep Ocean TrenchesThis process is called Subduction and makes the Deep Ocean Trenches
Subduction and Deep Ocean Trenches
More Detail than you want! Subduction!
Some Vocab Plate Convergent Plate Boundary Divergent Plate Boundary Transform Plate Boundary Sea Floor Spreading Magnetic Reversal Rift Zone Subduction Island Arc
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.
Kea and Loa
Tectonic Plates - names
Most of the volcanoes are located on or near ___________________ _________ volcano is the only one in the middle of a ___________.