Mid-Ocean Ridges form when the sea floor plates move Earthquakes occur and magma rises and meets or seeps out on the ocean floor, also called undersea volcano. As the magma piles up along the water, it cools down and becomes hard, which adds to the edges of the sideways moving plates. As the plates move and the magma builds up it then becomes 'constructive' and makes new ridges under water.
Subduction Zones are after results of when a mid ocean ridge forms. Subduction zones are smaller pieces of mid ocean plates that form which melt back into the Earth and become new thick layers of rock.
Earthquakes occur when the outer, brittle portions of plates induce stress that result in movement of the overlying plates. The stresses from convection can also deform brittle portions of overlying plates there by storing tremendous energy within the plates. Once the plates stress is exceeded brittle zones break suddenly which release the stored energy.
Mountain Ranges form when one tectonic plate big or small moves and collides into another plate, as the plates put pressure on each other one of the plates surfaces either goes up or down and mountain rangers are formed. typically for two plates to run into each other and from mountains both must be the same density and or material.
B. Mantle Convection moves using the concept of heat flowing through the earths rocky mantle which is soild rock made up of magma, It rides on the very top of the earths surface and as the plate tectonics move the mantle is there for shifted in different ways and changes the flow of magma and the pressure of the earths surface in places. Mantle is added to the growing edges of a plate when sea floor spreading occurs, the hot added material cools down by conduction and convection of heat. At the edges of the plate where the material thermally contracted cools down and becomes more dense, it sinks under its own weight in the process of the subduction at an ocean trench.
C. Plate tectonics only move a few centimeters a year. The way the plates are loctaed is everywhere there is a volcano or earth quake its marked on a map and usally they will outline where a plate lays. The world was once a super continent and over the years the worlds surface moved and now the earths plates lay where they are now.
http://www.pacificislandtravel.com/nature_gallery/platetectonics4.gif
http://www.go2add.com/images/LookingAtCrusts/ConvectionInTheMantle.gif
Bibliography.
http://library.thinkquest.org/17457/platetectonics/4.php
http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/description_plate_tectonics.html
http://www.platetectonics.com/book/page_11.asp
http://en.wikipedia.org/wiki/Mantle_convection
