Answer
Seafloor spreading is a constructive geologic process.
At divergent plate boundaries, where tectonic plates move away from each other, seafloor spreading occurs.
The heat from mantle convection currents makes the crust more plastic and less dense.
As the plates separate, the less dense material rises, forming elevated areas on the seafloor.
Eventually, the crust cracks, and hot magma fueled by mantle convection bubbles up to fill these fractures.
The cooled magma solidifies into igneous rock (specifically basalt), becoming a new part of Earth’s crust.
Mid-ocean ridges, such as the Mid-Atlantic Ridge and the East Pacific Rise, are where seafloor spreading occurs.
These ridges can be either slowly spreading (with tall underwater cliffs) or rapidly spreading (with gentler slopes)