Here's why:

* Seafloor Spreading: At mid-ocean ridges, new oceanic crust is constantly being formed as magma rises from the Earth's mantle and cools. This process is called seafloor spreading.

* Continuous Creation: As new crust is formed, it pushes older crust away from the ridge, resulting in a continuous conveyor belt of rock moving outward.

* Age Gradient: This means that the rocks found closer to the ridge are younger than those found farther away.

Other locations where you might find relatively young rocks:

* Volcanic Areas: Active volcanoes, both on land and underwater, produce new rock as lava flows and cools.

* River Deltas: Rivers carry sediment and deposit it at their mouths, forming deltas. This sediment can be relatively young, though it may include older material eroded from upstream.

While these are general areas where young rocks are found, it's important to note that the specific age of rocks can vary greatly within each location.