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 * __The Three Different Types of Boundaries on Our Dynamic Earth__

Convergent Boundaries

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Convergent Boundaries are where plates serving landmasses collide, the crust crumples and buckles into mountain ranges. There are three types of these; ocean-ocean, ocean-continent, and continent-continent. When the Eurasian Plate and the Indian Plate collided over 55 million years ago, they formed the Himalayas and Mount Everest. This is an example of a continent-continent convergent boundary. An example of an ocean-continent convergent boundary would be when the diving plate melts and is often spewed out in volcanic eruptions such as those that formed some of the mountains in the Andes of South America. These were formed by the Nazca Plate and the South American Plate. At ocean-ocean convergences, one plate usually dives beneath the other, forming deep trenches like the Mariana Trench in the North Pacific Ocean, the deepest point on Earth. These types of collisions can also lead to underwater volcanoes that eventually build up into island arcs like Japan.




 * Divergent Boundaries

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Divergent Boundaries are when magma rises and pushes plates apart. The process renews the ocean floor and widens the giant basins. A single mid-ocean ridge system connects the world's oceans, making the ridge the longest mountain range in the world (60,000 km). Almost all of the plates cause this. On land, giant troughs such as the Great Rift Valley in Africa form where plates are tugged apart. The African Plate and the Somali Plate. Scientists believe that millions of years from now, Eastern Africa will split from the continent to form a new landmass, if those two plates keep drifting apart.




 * Transform Boundaries**



Transform Boundaries are when plates grind or slide past each other. The San Andreas Fault in California is an example of a transform boundary, where two plates grind past each other along what are called strike-slip faults. The North American Plate and the Juan de Fuca Plate caused this. Scientists predict that Californa will split and eastern California will be disconnected. The halting motion often triggers large earthquakes, such as the 1906 one that devastated San Francisco. The same plates (North American Plate and the Juan de Fuca Plate) as the San Andreas Fault triggered this event. Alaska is experiencing many earthquakes because the Juan de Fuca Plate is rubbing or grinding against the North American Plate. Mr. Jones calls this boundary the eighth grade dance move!




 * Bibliography**

"Cocos Plate." //UCSD//. Web. 13 Nov. 2009. .

"Himalayan Mountains." //Himalayan Mountains//. Evisum Inc., 2000. Web. 13 Nov. 2009. .

"Mid-Ocean Ridge." //Science Daily//. Science Daily, Web. 13 Nov. 2009. .

"Plate Tectonics." //National Geographic//. National Geographic, Web. 13 Nov. 2009. [tectonics-article.html|http://science.nationalgeographic.com/science/earth/the-dynamic-earth/plate- tectonics-article.html].

[|convergent2.jpg] // Convergent Plate Boundary: crustal generation and destruction //. Encyclopedia Britannica. // Encyclopedia Britannica //. Web. 4 Nov. 2009. <[]>.
 * Pictures**

[|divergent2.jpg] // Divergent Boundaries //. // Plate Tectonics and Volcanos //. Web. 4 Nov. 2009. <[]>.

[|himalaya1.jpg] elosoenpersona,. // Machapuchare Summit (6.993m), Nepal //. 2007. // Flickr //. Web. 3 Nov. 2009. <[]>.

[|midoceanridge1.jpg] Giddings, Al. // Black Smokers //. 2009. National Geographic Society. // National Geographic //. Web. 3 Nov. 2009. <[]>.

[|sanandreasfault1.jpg] Degginger, Phil. // San Andreas Fault //. 2009. National Geographic Society. // National Geographic //. Web. 3 Nov. 2009. <[]>.

[|transform1.jpg] // Transform Boundary //. NASA. // Why isn't the earth perfect //. Web. 4 Nov. 2009. <[]>.