Actively eroding rocky shorelines are characterized by rock falls, collapsing caves and seastacks. Long-term shoreline retreat may be marked by the presence on the foreshore of material distinct in texture or composition, such as older relict sediments, backshore peat or shell assemblages underlying foreshore deposits. Seasonal, before and after storms. Semi-annual or annual, once seasonal variability is established. Historical records are commonly short.
Qualitative results can be misleading, and many methods have severe limitations.
Adjacent shoreline segments may respond differently to the same environmental conditions. Changes in relative sea level and in sediment supply are critical factors in coastal evolution and in the response of shorelines to environmental change. In general, coastal phenomena can be reliably anticipated only where extensive research and monitoring data exist. A lack of current change is no assurance of continued stability in the future, but information on changes in the shoreline position, especially over the longer term, may be useful for short-term empirical predictions. Monitoring shorelines and coastal sediment dynamics may provide a better understanding of the responses of the shoreline to human modifications and sea-level change.