ACT Preparation / Unit 22 ACT 2129 short lesson, about 20 seconds
Plate Tectonics
Captions available
The idea
Earth's outer layer is broken into plates that move. Their boundaries are of three kinds: divergent, moving apart; convergent, moving together; and transform, sliding side by side.
In practice
At a divergent boundary, new crust forms from rising magma; at a convergent one, one plate can sink beneath the other.
Where people slip
Name a boundary by the plates' relative motion.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
Unlocks
- Nothing yet depends on this.
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