Plate Tectonics!

1. Plate Tectonics! By: Heather Shams en.wikipedia.org/wiki/subduction

2. Pangaea: Theory or Real? • The first theory of Pangaea came from Alfred Wegener, who developed it from his other theory of continental drift. • The super continent theory was not accepted by other scientists at the time because Wegener did not have enough evidence and couldn’t explain his theories well enough. • Pangaea, meaning “all lands”, occurred during the Carboniferous time, and stayed together till around 300 million BC. en.wikipedia.org/wiki/subduction

3. Alfred Wegner • During the time his theory of continental placement was being discussed, scientists called “anti-mobilist” had a different theory in which the Earth was going through cycles of heating and cooling. This would cause expansion and contraction of land masses. • Alfred Wegner was also into astronomy, meteorology and climatology which helped him support his theory by knowing the gravitational movements of the sun and moon, and how that relates to the movements of our plates(what continents seat on, crust). • Arthur Holmes, who supported Wegner, thought that the mantle under the crust would be going through convection which would cause movements which would carry the plates. en.wikipedia.org/wiki/subduction

4. Convergent Boundaries • A convergent boundary is when two plates collide. • The plates either form a subduction zone, which is the process of when two tectonic plates crash into each other and one goes beneath the other and sinks into the mantle. This usually produces earthquakes( seismic waves through the earth), landslides(such as rock falls, deep failure of slopes and shallow debris flows, which can happenany where on the earth’s crust),mudslides(rapid movement of a large amount of mud formed from loose soil and water), and volcanoes(is an opening in a planet's surface or crust, which allows hot magma, ash and gases to come from below the surface). en.wikipedia.org/wiki/subduction

5. Convergent Boundary Continued… • Or a continental collision, which is when two plates, that are made out of continental crust, collide into each other. Because continental crust is too buoyant to sink into the mantle, some rocks crumble and others thrust outward to form our large mountain(a land mass that projects well above its surroundings ranges). en.wikipedia/wiki/continentalcollision

6. Convergent Boundary Example! • An example of this type of boundary(where the plates meet) line is with the oceanic plate, Juan de Fuca (along the west coast of North America) , and the continental plate, North America. Because oceanic plates are a lot more denser then continental plates, Juan de Fuca foes under the North America Plate thus forming many volcanoes and earthquakes in that area. www.nature.nps.gov/geology/usgsnps/pltec/converge.html

7. Divergent Boundaries! • A divergent boundary is when two tectonic plates move away from each other. • This type of boundary line forms trenches, rifts, and rift valleys. The most active divergent boundaries are normally in the oceans and are usually called mid-ocean ridges. They can also form volcanic islands which occur when two plates move apart from each other enough to create a gap. The molten lava then flows out and creates a shield volcano which later develops into a volcanic island. en.wikipedia.org/wiki/divergentboundaries

8. Divergent Boundary Example! • An example of this boundary line is the Mid-Atlantic Ridge. It separates the Eurasian Plate and North American Plate in the North Atlantic, and the African Plate from the South American Plate in the South Atlantic. en.wikipedia.org/wiki/mid-atlanticfault

9. Transform Boundaries • A transform boundary, or transform fault, runs along the boundary of a tectonic plate and it occurs when two plates slide against each other in opposite directions. The crust on both plates are not destroyed or created. • This type of boundary line can produce earthquakes and fault lines in the Earth’s crust. http://en.wikipedia.org/wiki/Transform_fault

10. Transform Boundary Example! • An example of this type of boundary is the San Andreas Fault. It runs 810 miles through Canada and into the United States. It is the tectonic boundary between the Pacific and the North American plate. http://en.wikipedia.org/wiki/San_Andreas_fault

11. Are We In Any Danger? • We live in on the North American Plate and the plates that border us is the Juan de Fuca, Cocas, Caribbean, Eurasian, and African Plate. Ohio is not in any serious dangers related to plate tectonics but the west coast will be getting many more earthquakes and volcanoes. In the very distant future, I anticipate California to split off of North America and become its own plate. en.wikipedia.org/wiki/subduction