Porlock Ridge and salt marsh, Exmoor, Somerset, UK. This salt marsh used to be agricultural land. The shingle beach (seen in the distance) has protected the coast from the sea. The beach is being eroded away, which allows the sea to frequently inundate the land behind the beach. This has enabled the salt marsh to develop. Salt marshes form on coastal mud flats such as estuaries. This salt marsh is part of an important coastal geomorphological site, which has developed over many years.