Fossil Mediterranean molluscs as sea-level indicators

Intertidal molluscs are known to occur in similar positions or zones on shores throughout the world. However, little is known about the extent to which these distributions are preserved in the fossil record. This study attempts to define the relationship to present sea level of live and dead intertidal molluscs in the Mediterranean, and utilizes this information to interpret the position at which Quaternary shorelines were formed. The preservation of zonation patterns in the fossil record is affected by post-mortem transport, breakage and burial of the shell material. To take account of such taphonomic changes, experimental studies of shell transport and burial under waves and unidirectional currents were made, and the distribution of dead molluscs on modern shores were compared with live distributions. It proved possible to predict the frequency with which certain species were deposited on the modern shore and, by analogy, the likelihood of their preservation in the fossil record. Thus death assemblages in fossil shorelines can be accurately related to past sea levels.