What creates new seafloor in the rift valleys?
continental drift
sedimentation
crust spreading
seafloor spreading
Volcanoes erupt at mid-ocean ridges, such as the Mid-Atlantic ridge. Seafloor spreading creates new seafloor in the rift valleys. This type of volcanism makes all of the ocean floor! Where a hotspot is located along the ridge, such as at Iceland, volcanoes grow high enough to create islands ( Figure below ).