Vocabulary Term HintDefinition EpicenterPoint on Earth's surface directly above an earthquake's focus Seafloor spreading Hess's theory that new seafloor is formed when magma is forced upward toward the surface at a mid-ocean ridge Riftlong crack, fissure, or trough that forms between tectonic plates moving apart at plate boundaries Subduction zone Location where one plate slips under a less dense plate at a convergent boundary
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