What is Plate Tectonics
The theory of plate tectonics, sometimes confused with the earlier theory of continental drift, is a comprehensive explanation of the composition of the Earth’s crust and how it is not a single solid sphere but a collection of individual plates of hardened rock that float on top of a viscous liquid mantle. The best way to envision this was put forth by the National Oceanic and Atmospheric Administration’s New Millennium Observatory on their site about tectonics. They suggested imagining a chocolate covered caramel candy bar that has been left in a hot area for a while. The chocolate breaks into pieces and moves on the flowing caramel center.
What is interesting about this theory is that the interactions of the plates can have catastrophic consequences for the immediate environment in areas where two plates meet. The areas where the plates meet are called plate boundaries. There are three types; convergent, divergent and transform fault.
A convergent boundary is one where when two pieces of tectonic plate come together one is forced beneath the other back into the mantle. This leads to a destruction of plate area. Mountain ranges are often formed when plates come together in this way.
A divergent boundary occurs when two plates move away from each other due to the force of magma pushing up between them. It is in this area that new seafloor is created.
A transform fault boundary occurs when two plates slide next to each other. When plates do this, it often causes earthquakes. This type of movement is called a slip fault. The San Andreas Fault in California is a prime example.
So, new sea floor is being created from divergent boundaries in the mid-ocean ridges, but how much new seafloor are we talking about?