What visual inspection term describes a small amount of material that separates from the face of an excavation and trickles down?

The term that describes a small amount of material that separates from the face of an excavation and trickles down is indeed referred to as raveling. Raveling typically occurs in soil or rock when the cohesion between particles weakens, causing them to loosen and fall away, potentially posing risks in excavation safety and stability. This process can lead to further erosion if not properly managed.

The other terms have distinct meanings in the context of excavation and geological formations. Subsidence refers to the sinking or settling of the ground, often due to underground material collapsing or being removed. Bulging indicates an outward protrusion due to pressure or instability in the material behind an excavation wall. Fissure describes a crack or split in a surface, which may indicate structural weaknesses but does not specifically refer to material trickling down as raveling does. Understanding these differences is crucial in evaluating excavation conditions and ensuring safety.