Mod+7.8+-+Alexandra+V


 * CONVERGENT BOUNDARIES:**

A convergent boundary is a tectonic boundary where plates move into each other and the crust crumples and buckles. There are three kinds of convergent boundaries. One kind is continental-continental, or otherwise known as continent-continent. Continent-continent convergences are when the plates supporting continents or land-masses converge. This causes one plate to dive under the other, causing the crust to buckle and form mountains. An an example of continent-continent convergences is the Himalaya Mountains. The Himalaya Mountains were formed when the Eurasian Continental plate crashed into the Indian plate 55 million years ago. Another kind of convergent boundaries is ocean-ocean. Ocean-ocean convergences involve two plates on the ocean floor moving together and one diving beneath the other, forming a trench. An example of ocean-ocean convergences is the Mariana Trench, which is deeper than Mount Everest is tall. The Mariana Trench was formed when the Pacific and Philippine plates converged near where present day Japan is. The third kind of convergent boundaries is ocean-continent. Ocean-continent convergences occur on coastlines. This kind of convergence happens when one ocean floor plate and one continent plate converge together to form a trench on the edge of an ocean. 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.


 * DIVERGENT BOUNDARIES:

A divergent boundary is when two or more plates are pushed apart to form troughs.



Divergent boundaries can happen either on ocean floors or on land. In the ocean, magma from Earth's mantle rises toward the surface and pushes the plates apart. Mountains and volcanoes rise along the seam. This process renews the ocean floor and widens the large basins. **** For example, the Mid-Atlantic Ridge separates Iceland and separates the North American and Eurasian plates. **Another example could be the East Pacific Rise which separates the Pacific, North American, Rivera, Cocos, Nazca, and Antarctic plates.
 * Divergent boundaries on land are a little different. When a continent is split across two plates, there is a chance that the plates will diverge and separate the continent to form a mid-ocean ridge. An example could be the Great Rift Valley in Africa, which forms as the African and Arabian plates are yanked apart. If the plates diverge years from now, eastern Africa will split from the continent to form a new landmass. Another example is the Red Sea, which was also formed as the African and Arabian plates are continuously being ripped apart.

****TRANSFORM BOUNDARIES:**

Transform boundaries are where plates move sideways in relation to each other.

Transform boundaries don't produce features like mountains or oceans, but the halting motion often triggers massive earthquakes. Sometimes when plates move against each other like this, they make large faults in the Earth. The San Andreas Fault is an example of a fault. The San Andreas Fault is separating the North American and Juan de Fuca plates. Another example of transform boundary faults is the Alpine Fault in New Zealand, which separates the Pacific and Indo-Australian plates. The Chaman Fault is also a transform boundary. The Chaman Fault separates the Eurasian and Indo-Australian plates.


 * BIBLIOGRAPHY:**

"Plate Tectonics." //Plate Tectonics, Tectonic Plates Information, Polls, News, Photos//. Xbox360, n.d. Web. 15 Nov. 2009. .

"Himalaya Mountains." //Himalaya//. N.p., 2000. Web. 15 Nov. 2009. .

Watson, j M. "Understanding Plate Motions." //Understanding plate motions [This Dynamic Earth, USGS]//. N.p., 5 July 1999. Web. 15 Nov. 2009. .


 * PICTURES:**

[|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. <[]>.