Here's why:

* Seafloor Spreading: Mid-ocean ridges are where new oceanic crust is formed. Magma rises from the Earth's mantle, cools, and solidifies, creating new crust.

* Movement Away from the Ridge: As new crust is formed, it is pushed away from the ridge on either side, like a conveyor belt. This process is called seafloor spreading.

* Age Gradient: The further away from the ridge you go, the older the rocks become.

So, the youngest rocks are found at the very center of the ridge, where they are constantly being created.