Here's why:

* Soil Formation: Soil forms over time through the weathering of rocks and the decomposition of organic matter. This process happens gradually, with new layers forming on top of older ones.

* Layers: The layers of soil are called horizons. The top layer, called the A horizon, is the most recently formed. The bottom layer, the C horizon, is made up of weathered bedrock and is the oldest.

It's important to note that soil profiles can vary greatly depending on location, climate, and other factors.