Here's why:

* Permeable soil: This type of soil allows water to pass through it easily. Think of sand or gravel. The spaces between the particles create pathways for water to flow.

* Aquifer: An aquifer is an underground layer of rock or soil that holds groundwater.

* How it works: Water seeps down through the permeable soil and collects in the layer below. This layer, often made of sand, gravel, or fractured rock, acts as a reservoir for groundwater.

Let me know if you'd like more details on how aquifers form!