Question #8b5a5
1 Answer
Plate boundaries exist because the earth's crust has cracked due to stresses in the mantle.
Explanation:
At one time all of the earth's crust is believed to have been in one piece. This giant chuck of crust was called pangea.
Stresses in the crust broke open cracks separating pangea into pieces. These pieces moved away from each other. New Crust coming up through the cracks pushed the pieces apart. Where the cracks appeared divergent boundaries were formed allowing water and magma from the mantle to reach the surface. This movement is thought to be caused by convection current in the mantle.
As the pieces were pushed apart at some point some of the pieces collided with each other. These collisions create convergent boundaries. The convergent boundaries create mountains, and subduction zones. The subduction zones cause earthquakes and volcanos.
The stresses created by movement of hot material in the mantle creates the break up and reforming of the crust that make in turn creates the plate boundaries.
