Earth's crust is broken into giant rafts drifting on hot rock beneath. Where they grind past each other the ground shakes in an earthquake; where they crash together the land buckles up into mountains over ages.
A cracked shell in slow motion
Earth's rigid outer layer is broken into tectonic plates that drift a few centimeters a year atop the softer mantle beneath. Where plates meet, three things can happen: they pull apart (divergent), push together (convergent), or slide past each other (transform).
Convergent boundaries push up mountains and cause deep earthquakes; divergent boundaries create new crust at ocean ridges; transform boundaries, like the San Andreas Fault, produce shallow quakes.
The Himalayas rise because the Indian plate collides with the Eurasian plate — a convergent boundary still lifting them today.
- Two plates grind sideways past each other, causing frequent quakes.
- Match this motion to one of the three boundary types.
- Give a real-world example.
What you should see: Sideways sliding is a transform boundary — the San Andreas Fault is a classic example.