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Plate Tectonics How Earth changed from being Pangea to separate continents Pangea Pangea! Plate tectonic theory- the idea that all of the continents were once one big “super continent” How can the continents move? Lithosphere - Upper part of the mantle. The lithosphere moves on top of the “plastic like” asthenosphere. (sort of like icebergs can move around on water) -The lithosphere is broken in 30 plates of different shapes and sizes Different plates • The plates move very slowly. • Some move up, some move down, some to the right, some to the left • The plates seam to fit like a puzzle. • Faults- areas where plates are touching. • Why do you think California (western north america) has so many earth quakes? • Why do you think Japan has so many tsunamis? How the plates move • There are 3 different ways the plates move • 1. Slide past each other- (Transform Faults) • 2. Colliding with each other (Converging) • 3. Splitting away from each other (Diverging) Sliding past each other Transform Faults -results in EARTHQUAKES & TSUNAMIS! -The pressure from the asthenosphere builds up so much that the plates move. Plates colliding into each otherConvergence • When 2 Continental plates collide into each other one will lift up over the other and form Mountains! • Subduction- when one plate is forced below another • (the word SUB means BELOW) • Ex. The Himalayas (India and Asia) Continental Oceanic Conversion Convergent Boundary cont. • When oceanic & continental plates collide, the oceanic plate SINKS under the continental plate because the oceanic plate is more dense (heavier).... heavier things sink. • The oceanic crust that was subducted will heat up (from friction) and re-melt into the asthenosphere. This creates magma- magma rises through the continental crust and forms volcanos! Convergence cont. -When 2 oceanic plates collide with each other a TRENCH forms. example- The Mariana’s Trench (in the Pacific Ocean) (this is the deepest part on the Earth!) Plates spreading from each otherDIVERGENCE! Question: What is underneath the crust? When 2 plates (of any kind) spread away from each other… magma comes up from the MANTLE and quickly cools on the ocean floor to form NEW CRUST! Ex. Mid Atlantic ridge (in the Atlantic ocean) Discovering Plate Boundaries A data rich exercise in which students discover plate tectonic boundary processes Seismology Map – Earthquake Locations and Depths Dale S. Sawyer Rice University Volcanology Map – Recent Volcanic Activity Dale S. Sawyer Rice University Geochronology Map – Seafloor Age Dale S. Sawyer Rice University Geography Map – Topography and Bathymetry Dale S. Sawyer Rice University
