Adivergent plate boundary is a boundary at which two tectonic plates move away from each other. as the plates move apart, magma rises upward between them and erupts onto the ocean floor as lava. this lava cools quickly to form solid rock. over time, these hardened lava flows build up on top of each other and are uplifted by tectonic forces to form mid-ocean ridges. based on this information, what type of rock are mid-ocean ridges made of? metamorphic rock sedimentary rock igneous rock eroded rock