The Mid-Atlantic Ridge is a divergent tectonic plate boundary that is on the ocean floor. A divergent boundary is when two tectonic plates move apart from each other. In this case, the plates are the South American Plate and the African Plate. As those plates pull apart, magma from below the Earth’s crust rises up and cools down in the water. As that happens, new pieces of the seafloor are created! Mountains underwater called seamounts also form due to the cooling magma. The Mid-Atlantic Ridge is also home to a lot of volcanoes because the plates are spreading apart. This proved Alfred Wegener’s theory of continental drift. The Mid-Atlantic Ridge stretches for over 10,000 miles from the Arctic Ocean to the southern tip of Africa. This is what the Mid-Atlantic Ridge is!