Sea-Floor Spreading

mid-ocean ridge
an undersea mountain chain where new ocean floor is produced; a divergent plate boundary
a device that determines the distance of an object under water by recording echoes of sound waves
sea-floor spreading
the process by which molten material adds new oceanic crust to the ocean floor
deep-ocean trench
A deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle.
the process by which oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary