The Earth's Tectonic Plate

The word tectonic plate comes from the Greek meaning "pertaining to building". This theory tries to explain the movements of the earths lithosphere ever since the past all the way up to now. Essentially, there are three main driving forces for the movement of the Earth's tectonic plates. They are mantle convection, gravity, and the Earth's rotation. Mantle convection is very similar to the theory developed by Holmes in 1929. There are large convection currents of molten material in the Earth's upper mantle. As these currents transmit energy to the Earth's asthenosphere new lithospheric material is pushed up toward the Earth's crust. Gravity is a secondary driving force for the movement of the Earth's tectonic plates. At mid-ocean ridges the elevation is higher than the surrounding ocean floor. As the currents within the Earth cause new lithospheric material to rise and spread away from the ridge, gravity causes the older material to sink toward the ocean floor and aid in the movement of the plates. The Earth's rotation is the final mechanism for the movement of the Earth's plates but it is minor in comparison to mantle convection and gravity.

Divergent boundaries are where the plates move away from each other and new crust is created. Convergent boundaries are where the plates collide with one another causing the subduction of one plate beneath the other and the transform boundaries are the final type of plate boundary and at these locations the no new crust is created and none is destroyed. Instead the plates slide horizontally past one