Final answer:
New mountains in the Atlantic Ocean form due to seafloor spreading at divergent plate boundaries, where tectonic plates move apart and magma rises to create new crust along the Mid-Atlantic Ridge.
Step-by-step explanation:
New mountains continually form on the floor of the Atlantic Ocean primarily due to the process of seafloor spreading at a divergent plate boundary. The Mid-Atlantic Ridge is an underwater mountain range that is part of a rift zone, where the Earth's tectonic plates are moving apart. As the plates diverge, magma rises from the mantle to fill the gap, creating new oceanic crust and, consequently, new mountains. This process is analogous to the creation of the Hawaiian island chain through volcanic eruptions, though the mechanism is different: in the Atlantic, the mountains form along a ridge due to the pulling apart of tectonic plates.
This phenomenon is part of the larger concept of plate tectonics, which is a theory explaining the movement of Earth's lithospheric plates. These movements are associated with a variety of geological processes, including earthquakes, mountain building, and volcanic eruptions. While the Atlantic Ocean features a divergent boundary where new crust is formed, other areas of the Earth feature convergent boundaries, where crust is recycled back into the mantle through subduction zones, balancing the material added through rifts.