Inferencia del tiempo relativo de funcionamiento del sector septentrional del muelle de la linterna de Portus

The detailed analysis of the bioerosion structures and cementing organisms recognized in the artifactual assemblage of the northern sector of the lantern quay (Portus, Italy) has allowed us to infer its relative period of operation. The life history of this assemblage has been established in 5 phases: (1) first colonization; (2) deposition of the column fragments; (3) second colonization; (4) bioerosion; (5) deposition of the Wall, third colonization, vertical displacement and new bioerosion. In particular, it is established that the fragments of columns are underlaying with respect to the wall blocks. The presence of a very high bioerosion rate (>70%) due to the activity of clionaida sponges in the fragments of marble columns, provides a relative time of their activity, approximately 20 years. The discovery of an adult specimen of Pholas dactylus in a block of the walls deposited after the fragments of columns, allows to infer its activity over a maximum of 12 years. It is established, therefore, that the relative operating time of the studied sector of the quay could be established as between 30-35 years. The environmental conditions in this port sector would initially be shallow marine, normal to brackish salinity, with tidal influence but of low hydrodynamic energy, fine sediment and zero sedimentation rate. These conditions would change until total filling, disuse and abandonment.