and the Bay of Bengal, which is the world's largest bay. Bays also form through coastal erosion by rivers and glaciers. A bay formed by a glacier is a fjord. Rias are created by rivers and are characterised by more gradual slopes. Deposits of softer rocks erode more rapidly, forming bays, while harder rocks erode less quickly, leaving headlands. See also References Bodies of water Coastal and oceanic landforms Coastal geography Oceanographical terminology