2. Plate Tectonics Earth’s Interior Pangaea Plate Movement Plate Boundaries

3. Pangaea Theory stating all of the continents were once joined as a “super-continent” Alfred Wegener proposed this idea Looked at specific evidence (fossils/rock record/fit) from one continent to the next. Proposed all continents once fit together, then broke apart. Hence the term, Continental Drift.

4. Plate Movement Plates move because the Asthenosphere –a layer of partially melted rock that is able to flow (like silly putty) with the aid of convection currents (“heat currents”) –Convection currents slowly move the ridged crust in a specific direction –Movement per year is about the same as how long your fingernails grow per year (how much is that!?)

5. Plate Movement When plates move, they collide with one another’s boundaries. Three main types of boundaries -Convergent -Divergent -Transform

6. Plate Boundaries Type of Boundary Convergent –Oceanic-oceanic –Oceanic-continental –Continental- continental Divergent Transform Result of Boundary Plates come together –Subduction zone/ volcanic islands –Subduction zone/ volcanic mountains –Non-volcanic mountains Plates moving away from one another, creates new sea floor Plates sliding past one another, creates earthquakes

7. Convergent Boundaries Oceanic-Oceanic Boundary Plates converge creating a subduction zone—one plate slides underneath the other plate creating a volcanic arc (volcanic islands) This will also create a trench in the ocean

8. Convergent Boundaries Oceanic-Continental Boundary Subduction zone—oceanic plate slides under continental plate because it is more dense. The oceanic plate breaks off and melts once it is heated in the mantle. The melted plate then comes through the continental plate to create volcanoes on the continental plate Additionally, this will create an oceanic trench

10. Convergent Boundaries Continental-Continental When two continental plates come together, the two plates “crumple” much like a piece of paper This creates huge mountain ranges, e.g. Himalayans & Mt. Everest

11. Divergent Boundaries If two continental plates diverge, the continent would stretch much like a rubber band getting thinner and thinner with each stretch

12. Divergent Boundaries Occur mainly on the sea floor between oceanic plates When the sea floor spreads, it splits, thus creating a way for the mantle to rise through the crust, creating new sea floor. Example: Mid-Atlantic Ridge.

13. Transform Boundary Transform boundaries slide past one another laterally Can slide uniformly or they can get “stuck” at a particular point until there is enough pressure to move past the “stuck” point When there is enough pressure to move beyond this point, we may feel the movement as an earthquake depending on the intensity An example of a transform boundary is the San Andres Fault in California

14. Hot Spots There are several volcanoes caused by “hot spots” A hot spot is a point in the mantle where a plume of hot material rises to the surface causing an area of geo-thermal activity. Hot spot does not move, the plate does ExamplesExamples of hot spots include: the Hawaiian Island Chain and Yellowstone National Park One theory indicates hot spots as the reason for the break up of Pangaea