The Piacenzian carbonate succession of Villa Buonriposo records the last stages of the Pliocene marine deposition in the Valdelsa Basin. The car bonate succession consists of a Lower Unit (LU) mainly composed of detrital, terrigenous carbonate sediments settled in an alluvial-to-shoreface environment. Pebble conglomerates and chalky carbonate/sulphate arenites are derived from the erosion of the evaporitic-dolomitic Burano Formation and its derivation the "Calcare Cavernoso". The Middle Unit (MU) composed of alternated chalky, carbon ate/sulphate arenites and irregularly bedded skeletal limestone grading in the upper part to massive limestone with rhodoliths, is interpreted to correspond to the marine carbonate factory developed in a shallow, low-energy marine setting corresponding to a carbonate ramp. Rich but low-diversity heterozoan epiphytic assemblages of the Rodechfor/Rhodalgal type, are composed of branching and crustose coralline algae, foraminifers with dominant Elphidium gr. crispum and sparse Amphystegina sp., associated with echinoids, serpulid worms and bryozoans. The skeletal remains of these organisms which live supported by meadows of seagrass (Posidonia, bushy brown and green algae), were locally accumulated in place at the death of the vegetal support or reworked and redeposited probably by storm currents, as fine-grained sometimes graded bioclastic debris. The Upper Unit (UU), characterized by pebble conglomerates similar to those occurring at the base of the section, attests to the regression from coastal to alluvial conditions and the last stages of the marine deposition in the Valdelsa Basin. The fabric and composition of the car bonate lithofacies suggest that this carbonate succession was deposited on a narrow, low-energy ramp developed on the northern coast of a small island corresponding to the present Poggio del Comune Hill. This shallow setting appears to have represented a shoal connecting the Valdelsa Basin to the adjacent Volterra Basin. The components of the Piacenzian assemblages, similar t o those living at present in the western Mediterranean, register depositional conditions in a temperate-warm climate.