PLATE TECTONICS. By: Rachel Deal

History of Pangaea In 1911 Alfred Wegener thought of the “Pangaea Theory” which was that, 300 million years ago the continents were combined and the earth was one. Many scientists disagreed with Wegener and believed in static continents and land bridges. Wegener didn’t have enough evidence to prove his theory was correct. Now we know that this theory was incorrect because the information he would give just doesn’t make sense. Continents did not move on the ocean floor, they would form plates which floated on the asthenosphere.

Alfred Wegener Earned a Ph.D. in astronomy which helps him in the study of geology. Published The Origin of Continents and Oceans in 1920 and new additions came out in 1922 and 1929. Named the “Pangaea theory” from the Greek word meaning “all of earth.” http://www.ucmp.berkeley.edu/history/wegener.html

Convergent Boundaries Convergent boundaries are locations where lithospheric plates are moving towards each other which causes plate collisions that can make volcanoes, earthquakes and crystal deformation. Convergent boundaries can cause volcanoes. Example: The oceanic lithosphere slides towards the continental lithosphere and collide. The oceanic lithosphere will slide under the continental lithosphere and push hot magma up to form a volcano. http://geology.com/nsta/convergent-plate-boundaries.shtml

Convergent Boundary http://tasaclips.com/illustrations.html

Divergent Boundaries A divergent boundary is when plates move away from each other. This occurs above rising convection currents which push up on the bottom of the lithosphere and move the plates in the direction of the currents and break apart. Divergent boundaries can cause trenches. Example: When the oceanic lithosphere plates flow on top of the currents underneath and slide way from each other. This will cause a trench, a depression in the ground. http://geology.com/nsta/divergent-plate-boundaries.shtml

Divergent Boundary http://tasaclips.com/illustrations.html

Transform Boundaries Transform boundaries are places where two plates slide against each other. The area that forms a transform boundary is called a transform fault. This causes earthquakes, mudslides and landslides. Example: Two oceanic lithosphere plates run along each other in a horizontal motion. http://geology.com/nsta/transform-plate-boundaries.shtml

Transform Boundaries http://www.ncaggregates.org/rock_talk.php?file=mountains

Real World Ohio is on the North American Plate. All of the United States is on this plate. The Caribbean, Cocos, African, Eurasian, South American and the Pacific Plate boarder most of North America. California is the only U.S. state that would be in danger caused by tectonic plates because it is very close to the Pacific Plate. In the future I predict earthquakes. In the west of the U.S. there are already earthquakes and I think they will spread.

http://www.learner.org/interactives/dynamicearth/plate.html