Remember from Part One that groundwater generally will flow downhill. Petroleum product thickness contour lines are constructed in the same manner as elevation contour lines. These contours tend to wrap around in concentric circles. Review Figure 5 with the class. The figure below is a side view or cross-section of a water table aquifer .
Rain water hits the ground and infiltrates into the soil or runs off into a body of water.
A confining layer of silt or clay stops the water from moving deeper. The sands and gravels above the confining layer becomes saturated with water because the pore spaces between the grains are filled with water. The water- saturated zone is called the water table aquifer. The upper surface of the water table aquifer is the water table. Above the water table is the unsaturated zone .