The Geosphere Practice Test

This item tests how tectonic plates move at different boundary types. The boundary where plates slide past one another horizontally is a transform boundary. In this setting, the motion is mainly side-to-side rather than toward or away, so crust isn’t being created or destroyed at the boundary. The sliding motion builds up stress that is released as earthquakes along faults, often—think of the San Andreas Fault where the Pacific and North American plates grind past each other. Divergent boundaries involve plates moving apart, creating new crust at mid-ocean ridges or rift valleys. Convergent boundaries bring plates together and can lead to mountain building or subduction, where one plate sinks beneath another. Subduction zones are specific to convergent boundaries and involve downward motion, not horizontal sliding.