The seafloor spreads apart at mid-ocean ridges, which are underwater mountain ranges. Here's how it works:

* Magma from Earth's mantle rises up at the mid-ocean ridge.

* The magma cools and solidifies to form new oceanic crust.

* The new crust is pushed away from the ridge on either side, creating a rift valley.

* This process is continuous, pushing continents apart and expanding the ocean floor.

The rate at which the seafloor spreads varies, but it's typically a few centimeters per year.

Here are some examples of seafloor spreading rates:

* Mid-Atlantic Ridge: 2.5 centimeters per year

* East Pacific Rise: 15 centimeters per year

Seafloor spreading is a fundamental process in plate tectonics, driving the movement of continents and shaping the Earth's surface.