Tidal notches: A sea-level indicator of uncertain archival trustworthiness

In this paper, after a short summary on the processes and rates of bioerosion that contribute to the deepening of a tidal-notch profile, some Mediterranean case-studies are presented, where a tidal notch is prevented either from forming or from being preserved. Furthermore, as shown also in a complementary paper, the recent global sea-level rise is preventing the development of new tidal notches in the present mid-littoral zone. This very useful sea-level indicator, of past temporary standstills of the relative sea level in carbonate rock areas, is of great value in assisting interpretations of relative sea-level change in locations where it is preserved. The possibilities of absence of formation or of preservation, however, imply that it should be interpreted carefully before reconstructing local relative sea-level histories. In particular, the lack of fossil tidal notches cannot be relied upon to interpret the absence of past periods of relative sea-level stabilization.

► Present tidal notches do not form due to recent global sea-level rise.
► Examples of well marked fossil tidal notches absent from the nearby sites.
► Examples of local micro-climate influence on tidal notches.
► Quality of the rock preventing reliable tidal-notch development to be recognized.
► Case studies where tidal notches could develop only at specific periods.