Thursday, March 13, 2008

Tectonic Plates Shaping the Earth

Have you ever wondered how the earth you live on got the shape it has? There is one simple answer: tectonic plates. Convergent, divergent, and transform boundaries play a big role in the way the earth is formed and changing.
A convergent boundary is when two plates collide and one plate goes underneath the other. This can happen when a continental and oceanic plate collides into one another. The thicker and less dense continental plate overrides the thinner more dense oceanic plate. This process us known as subduction. The partial melting produces magma chambers above the subducting oceanic plate. If a magma chamber rises to the surface without solidifying the magma will break through in the form of a volcanic eruption. There are many affects from volcanoes on our earth. The lava changes the surface and many more. This can also happen with two oceanic plates. The older plate will subduct because of its higher density. It is forced to the mantle where the plate begins to melt. Magma chambers are produced and the ones that reach the surface break through to form a volcanic eruption cone. Convergent boundaries can also happen with two continental plates. This type is very powerful. The two thick continental plates collide and both of them have a density that is much lower than the mantle, which prevents subduction. So, instead it can cause extensive folding and faulting of rocks within the two colliding plates. Convergent boundaries are just one thing that affects the earths shape.
Another type of tectonic plate movement is Divergent boundaries. This is the opposite of convergent. In this action two plates are moving away from each other. This normally occurs above rising convection currents because this process usually involves two oceanic plates. A divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from one another. This forms rifts which result in rift valleys. Divergent boundaries are from the stress called tension.
The last type of tectonic plate movement that is shaping the earth is transform boundary. This occurs when tectonic plates slide and grind against each other along a transform fault. This forms a zigzag plate boundary. This changes the earth’s shape because it deforms parts of the earth and it makes parts of the earth farther apart.
There are a few of major plates and a few smaller, or minor, plates. Six of the majors are named for the continents surrounding them, such as the North American, African, and Antarctic plates. Though smaller in size, the minors are no less important when it comes to shaping the Earth. The tiny Juan de Fuca plate is largely responsible for the volcanoes that mark the Pacific Northwest of the United States. Tectonic plates can cause earthquakes, volcanoes, rift valleys, etc., which obviously change the earth’s shape. (RS2)


Anonymous said...

Very nice it looks like you did your research. You are a genious and a good writer. This is A material. Good Work!

Anonymous said...

nice job rachal lots of info this prolly got a 100%

Anonymous said...

This helps a lot this isn't even in my science book.