The environmental evolution, inferred from the sedimentary sequence, that has occurred during the last three millennia in a drained coastal marsh in the Tiber delta is presented. The stratigraphy of the sediments has been revealed through excavation of 7 km of trenches in an area of about 1.5 km2. The most evident environmental variations are represented by the transformation of freshwater marshes into brackish-water marshes, around the ninth-eighth centuries bc, and from brackish-water to freshwater marshes during the fourteenth-fifteenth centuries ad. The change in the water salinity was produced by the opening and closure of an inlet connecting the marshes and the sea because of the evolution of the delta. Other environmental variations are reflected in the fluctuations in the water level of brackish marshes: in a general trend towards an increase in water level, probably caused by the late-Holocene sea level increase, some phases of water decrease in the range of 10-20 cm occurred. The majority of the environmental changes were largely produced by erosion and sedimentary events connected with Tiber delta variations induced both by human impact and climate. The lower water levels were contemporary with glacial advances in the Alps and the Apennine chains. At least one of the five decreases of the water level was contemporaneous with a marine regression documented in Italy. © SAGE Publications 2011.

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