At divergent boundaries, two tectonic plates are moving away from each other. As they pull apart, magma (molten rock) from the Earth's mantle rises to fill the gap, creating new crust. This process is called seafloor spreading. * Features: Mid-ocean ridges (underwater mountain ranges), rift valleys (like the East African Rift Valley), and volcanoes (often less explosive). * Activity: Frequent but relatively shallow earthquakes. * Convergent Boundaries: *