The plates make up Earth's outer shell, called the lithosphere. This includes the crust and uppermost part of the mantle. Churning currents in the molten rocks below propel them along like a jumble of conveyor belts in disrepair. Most geologic activity stems from the interplay where the plates meet or divide.
The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart; and transform, where plates move sideways in relation to each other.
Convergent Boundaries
Where plates serving landmasses collide, the crust crumples and buckles into mountain ranges. These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass.
Divergent Boundaries
At divergent boundaries in the oceans, magma from deep in the Earth's mantle rises toward the surface and pushes apart two or more plates. Mountains and volcanoes rise along the seam. The process renews the ocean floor and widens the giant basins. A single mid-ocean ridge system connects the world's oceans, making the ridge the longest mountain range in the world.
Transform Boundaries
The San Andreas Fault in California is an example of a transform boundary, where two plates grind past each other along what are called strike-slip faults.
The movement of the plates creates three types of tectonic boundaries: convergent, where plates move into one another; divergent, where plates move apart; and transform, where plates move sideways in relation to each other.
Convergent Boundaries
Where plates serving landmasses collide, the crust crumples and buckles into mountain ranges. These convergent boundaries also occur where a plate of ocean dives, in a process called subduction, under a landmass.
Divergent Boundaries
At divergent boundaries in the oceans, magma from deep in the Earth's mantle rises toward the surface and pushes apart two or more plates. Mountains and volcanoes rise along the seam. The process renews the ocean floor and widens the giant basins. A single mid-ocean ridge system connects the world's oceans, making the ridge the longest mountain range in the world.
Transform Boundaries
The San Andreas Fault in California is an example of a transform boundary, where two plates grind past each other along what are called strike-slip faults.