Characteristics of the Environment - Field Sampling: Principles and Practices in Environmental Analysis - page 47

FIGURE 2.12 Movement of water through a soil having layers of differing
texture and composition.
energy source it cannot move from small to large. Thus, the water will not move into the
gravel layer unless there is enough pressure exerted by water buildup to move it from the
small sand pores into the larger gravel pores.
Lateral movement along boundaries, as shown in Figure 2.8, will continue until one of
two things happens: the water encounters a change in the horizon that will allow deeper
movement or the water above the horizon accumulates to such an extent that it exerts
enough pressure to push the water lower. In Figure 2.8 water-carrying contaminants
encounter a compacted layer that prevents deeper movement. When a hole in the
compacted layer is encountered the water moves deeper. Note that it still continues to
move further along the compacted layer. Also, once through the compacted layer it
moves in both directions (left and right). Almost any change in the composition or