Disturbance

• a cultural deposit is said to be disturbed when the original sequence of deposition has been altered or upset by post-depositional factors. Agents of disturbance include natural forces such as stream or wind erosion, plant or animal activity, land-slides etc.; and cultural forces such as later excavations.
• Any event or series of events that disrupt ecosystem, community, or population structure and alters the physical environment.
  Source: Terms of the Environment