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Dynamic Earth

Convergent Plate Boundaries- Convergent Plate Boundaries are when two plates collide. Land-Land A land to land plate collision often buckles into mountains. India and Asia collided 55 million years ago, and started to form the Himilalaya Mountains. The mountains continue to get higher. Ocean-Land Subduction usually occurs in this situation. When that happens, an overlying plate lifts over top of the diving plate. The diving plate melts and can create volcanic eruptions. Ocean-Ocean One of the plates will subduct underneath the other plate. The older plate normally subducts, because it has a higher density. The diving plate begins to melt the lower it goes into the earth. then, magma chambers form. The magma chamber rises to the surface, and the magma breaks through the surface, creating a volcanic eruption. Examples for Convergent:


 * The Washington-Oregon coastline is an example of a convergent boundary. There, the Juan De Fuca Plate is subducting under the North American Plate. That causes volcanic mountains on the coastline.
 * The Andes Mountain Range is a convergent boundary. The Nazca Plate is subducting under the South American Plate. It is causing mountains to form and grow.
 * Mt. Everest is another example of a convergent boundary. Mt. Everest is in the Hemilayan Mountain Range. It was formed from the Indian and Asia Plates colliding and folding into mountains.

Divergent Plate Boundaries

Divergent Plate boundaries happen when two plates move away from eachother. Magma can come through the plates. The magma hardens and creates crustal material. This type of plate boundary is most common in oceans. The process then repeats itself.

Examples for Divergent:


 * The Atlantic Mid-Ocean Ridges is an example of a divergent plate boundary. There, the African and South American Plates are moving away from eachother, and creating new crust. The new crust is what makes the ridges.
 * In Iceland, there are new volcanoes growing all the time. These volcanoes are formed by the North American and the Eurasian Plates spreading apart.
 * Another example is the African Plate and the Antarctic Plate that are seperating and creating ridges in the ocean and on the coast of Antarctica.

Transform Plate Boundaries

In Transform Plate boundaries, two plates slide past one another. The place where this happens is called a transform fault. Most transform faults are found in ocean basins. Earthquake activity is usually a cause of transform plate boundaries. There are not normally volcanoes with transform boundaries.

Examples for Transform:
 * The San Andreas Fault Zone in California causes most of the earthquakes in The United States. The San Andreas Fault was created from The North American and Pacific Plates sliding past each other.
 * The Gulf of California has transform faults. That forms the Cascadia Subduction Zone. The plates involved are North American and Pacific Plates. This also causes earthquakes.
 * The African and Eurasian Plates slide past each other, creating a fault in the northern Atlantic Ocean. This can cause tsunamis.

Bibliography

"Plate Tectonics." //Plate Tectonics, Tectonic Plates Information, Facts, News, Photos--National Geographic//. n.p., 2009. Web. 14 Nov. 2009. 

//Convergent Plate Boundaries//. n.p., 2009. Web. 14 Nov. 2009. .

"Transform Plate Boundaries." //geology.com//. n.p., 2009. Web. 14 Nov. 2009. .

"Divergent Plate Boundaries." //Lesson//. n.p., 2003. Web. 14 Nov. 2009. .