The Ria of El Barquero, in the north-western coast of Spain, has only recently been altered by anthropogenic structures, so that effects of such interferences in the natural dynamic processes of the coast are in some way measurable. Two ports have been built in the last decade, although only the one in the eastern part of the Ria interrupt the littoral drift of sand, thus causing important erosive effects towards the south and in the inner part of the Ria, where a turistic beach exists. Since 1990 the beach has experienced a mean retreat of 15meters, with the total destruction of the dune belt in the east part and complete disappearance of the road bordering the beach. On the other hand, new incipient beaches and increasing of others upstream of the ports have occurred. The beach of Bares, in the northern part of the Ria, has an interesting archaeological site (a roman villa and a medieval church and cemetery) on a promontory, a brecciated quartz dike dividing the beach. An important part of the site, still occupied in the XVIII century, has already disappeared due to erosion. No recent human interventions can be invoked to provoke such erosion, so natural causes, mainly the rising of sea level, can be deduce
