Plate Tectonics

1. Plate Tectonics By: Maddie O’Toole

2. The History of Pangaea Alfred Wegener, who was a geologist and a meteorologist, proposed the 1st theory of continental drift. He made an hypostasis that about 200 million years ago there was one large supercontinent consisting of all of Earth’s land masses, and it was called Pangaeawhich means all Earth and was there in the Carboniferous time period. Not all scientists originally believed in Wegener’s theory, because he didn’t have enough evidence or exclamation for why the continents actually moved. He didn’t have evidence for why the mountain ranges and other features didn’t continue we’re the continents split or other things like that. Also some people believed a theory that the planet was a molten ball on the inside and nobody believed that the sides could cool enough once it cracked. Later, some scientists started to believed Wegner’s theory because during the controversial time of this topic they thought that the Earth is going throughout heating and cooling cycles which caused expansion and contraction of the land masses.

3. Convergent Boundaries A convergent boundary is a deforming region where 2 or more platesmove toward each other and collide, and one is pushed down underneath the other plate. Earthquakes and volcanoes are common near convergent boundaries as a result of pressure, friction and plate material melting in mantle. An example of a convergent boundary is the boundary between the Pacific and Juan de Fuca Plates. It’s marked by a submarine mountain chain which is known as Juan Fuca Ridge which is about 500 kilometers long. Most trenches are caused by the movement of tectonic plates.

4. Divergent Boundaries Divergent boundaries are linear features that lie between two tectonic plates moving away from each other. This occurs above rising convection currents. The current then pushes up at the bottom of the lithosphere and causes plate material to be lifted along the direction of flow. This occurrence causes a mid ocean ridge, which is an area of the seafloor that is higher then the surrounding area. Divergent boundaries sometimes do produce earthquake activity, and if the boundaries form on continents then it can make a line of volcanoes.

5. Transform Boundaries Transform boundaries are where two plates slide past one another. When the two plates slide past each other no plates are added destroyed. The fraction zone is what forms transform plate boundaries, and this zone is known as a transform fault. Large earthquake activity is usually what occurs around transform boundaries. When an earthquake takes place this causes landslides and mudslides.

6. Real World Connections The US is mostly located on the North American Plate. The Pacific Plate borders most of the US, and so does the North American Plate and the Juan Fuca Plate. We are in danger of serious hazards because California is on the North American Plate and the Pacific Plate, which is a major fault line, and it is called the San Andreas Fault. The San Andreas Fault is hazardous because it can cause major earthquakes. Based on what I have learned about plate tectonics I think that in the distant future, plate tectonics are going to make the continents form together again.

7. Bibliography • http://www.ucmp.berkeley.edu/geology/techist.html • http://geology.com/nsta/divergent-plate-boundaries.shtml • http://www.kidsgeo.com/geology-for-kids/0045-divergent-boundaries.php • http://geology.com/san-andreas-fault/ • http://en.wikipedia.org/wiki/North_American_Plate • http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/description_plate_tectonics.html • http://www.ucmp.berkeley.edu/geology/techist.html • http://scign.jpl.nasa.gov/learn/plate2.htm