Which natural process is demonstrated by building mounds of dirt and pouring water in the described erosion activity?

• A. Weathering
• B. Condensation
• C. Evaporation
• D. Erosion

Answer: (D)

Erosion is the movement of soil and rock from one place to another by natural forces, like water. In this activity, pouring water over built-up dirt causes the soil to loosen and be carried away by the moving water, typically downslope. The key idea is that material is removed from its original location and transported, which is what erosion describes. Weathering, by contrast, would break the dirt apart in place without moving it. Condensation and evaporation are changes of water’s state and don’t explain soil transport. So the observed effect—soil being washed away by water—demonstrates erosion.