This is a drawing of the Earth's lithosphere.
Click on image for full size
Clues to Plate Movements
Many kinds of surface features are clues that our lithosphere is sliding.
Two types of features can form when plates move apart. At mid ocean ridges, the bottom of the sea splits apart and new crust is formed from molten rock, or magma, rising from the mantle. Continental rifts form when a continent begins to split apart. If a continental rift continues to split a continent apart it can eventually form an ocean basin.
When two plates move towards each other, several features can form. Often, one of the plates is forced to go down into the hot asthenosphere at a subduction zone. Volcanoes may form when a subducted plate melts and the molten rock comes to the surface. If neither plate is subducted, the two crash into each other forming huge mountains.
If these features are found on a planet's surface, they provide evidence that the planet's surface is in motion. The sliding lithosphere makes Earth special because there are only a few other planets that have a surface in motion.
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