coasts and sea

• destructive wave: when backwash is stronger than swash, material is eroded
• constructive wave: when swash in stronger than backwash, material is deposited
• compressed air: air is trapped in cracks of rocks and compressed by waves, pressure is increased, when waves retreat that air expands like an explosion, this can shatter rock
• bay: a wide, curved opening into the coast. soft rock, such as shale is eroded by the 4 processes of coastal erosion. eg dublin bay
• sand spit and lagoon: a sandspit begins where there is a change in the direction of a coastline, long shore drift loses some of its energy and deposits material at a faster rate than it can be removed. gradually, these deposits build up, spit extends further across bay. if sand spit continues to grow, it will reach far side of bay to form a sandbar. a lagoon is formed. over time the lagoon begins to fill with silt and mud from rivers that may flow into it.
• sea wall: a wall made of concrete built between the sea and coastal town
• rock armour: large boulders placed at the base of soft cliffs or in front of sand dunes
• groynes: low walls, often made of wood, that are built at right angles to the coast
• gabions: wire cages that are filled with small stones, placed along beaches