What defines the valley walls?

The valley walls are defined by the slopes that rise above the valley floor. These slopes play a critical role in shaping the overall topography of the valley and are typically composed of more consolidated materials such as rock or soil that support the structural integrity of the valley. The steepness and height of these walls can vary based on geological processes, erosion, and sediment deposition.

In contrast, the other options do not accurately describe the defining features of valley walls. Soft clay deposits relate more to sediment characteristics rather than the structural nature of valley walls. The deepest part of a river typically refers to the channel or thalweg rather than the physical boundaries of the valley itself. Being below the water table pertains to groundwater features rather than the geological features that delineate valley walls. Thus, the distinction of valley walls is primarily characterized by their elevation and slope relative to the valley floor.