Paleoecology of a Pliocene Rocky Shoreline, Salton Trough Region, California

The Pliocene Imperial Formation, Salton Trough region, California, locally overlies metamorphic basement at contacts representing rocky shorelines. Rocky shore occurrences are best developed as probable wavecut notches in marble basement which contain dense concentrations of marine borings. The borings, which represent an in situ rocky shore community, consist of Gastrochaenolites (produced by the bivalve Lithophaga), Entobia (produced by clionid sponges), Typanites (produced by worms or barnacles), Maeandropolydora (produced by polychaetes), and shallow pits produced by echinoids. This community represents the Typanites ichnofacies and has close parallels in other Neogene boring assemblages along carbonate rocky shores. Encrusting epifauna associated with the borings include barnacles and corals. Coastal sedimentation along the rocky shorelines is represented by a high-energy facies of skeletal limestone which contains clasts of basement marble supplied by bioerosion.