1. Accumulation: The groundwater accumulates above the impermeable layer, forming an aquifer. This is like a giant underground lake or reservoir. The water table, the upper surface of this saturated zone, rises.
2. Lateral Flow: The water will flow horizontally, seeking a path of least resistance. It might move along the top of the impermeable layer, looking for an opening or a less resistant area where it can seep through or continue its downward journey.
3. Discharge: The groundwater may eventually find a way to discharge. This can occur:
* Springs: The water emerges at the surface, often where the impermeable layer intersects the surface of the land.
* Wells: If humans drill into the aquifer, the groundwater can be extracted for use.
* Rivers and Lakes: Groundwater can seep into surface water bodies, contributing to their flow and water level.
4. Pressure Buildup: If the water has nowhere to go and keeps accumulating, the pressure in the aquifer can increase. This can lead to:
* Artesian Wells: If the pressure is high enough, water can flow freely from the well without pumping.
* Overlying Rock Fracture: In extreme cases, the pressure can cause the overlying rock to fracture, providing a pathway for the water to escape.
5. Geological Changes: The interaction of groundwater with the impermeable layer can cause changes to the surrounding rock:
* Dissolution: If the impermeable layer is made of soluble rock like limestone, groundwater can dissolve it over time, creating caves and sinkholes.
* Mineral Deposition: As groundwater moves, it may dissolve minerals from one layer and deposit them in another. This can create mineral veins or other geological formations.
In short, the interaction of groundwater with an impermeable layer is crucial for shaping the landscape, influencing water availability, and impacting various geological processes.
