What geological feature is primarily formed at divergent plate boundaries?

At divergent plate boundaries, tectonic plates move apart from each other, leading to the formation of mid-ocean ridges. These geological features arise as magma from the mantle rises to fill the gap created by the separating plates. When the magma cools, it solidifies to form new oceanic crust, which can build up over time to create a ridge that rises above the surrounding sea floor. This process not only generates new crust but also contributes to the geothermal activity characteristic of mid-ocean ridges, often seen in the form of hydrothermal vents and associated ecosystems.

In contrast, mountain ranges are typically associated with convergent plate boundaries where two plates collide. Earthquakes can occur at any type of plate boundary, but they are not a defining feature of divergences specifically. Volcanic arcs are generally formed at convergent boundaries where an oceanic plate subducts beneath a continental plate, leading to the creation of volcanoes. Thus, the distinct process of spreading and creation of new oceanic crust makes mid-ocean ridges the primary feature formed at divergent plate boundaries.