Salt marshes may be formed behind a spit. The zone behind a spit becomes a sheltered area. Water movement slows down and so more material is deposited. Deposition may form a salt marsh.

Creates a salt marsh which can provide habitats for wildlife and a natural defence against erosion and flooding. Salt marshes are diverse ecosystems supporting many species.

Visit BBC Webwise for full instructions The Gower peninsula has been described as having all of Wales' geography in one ... grassland, salt marsh, ancient woodland, mature sand dunes, craggy ...