Transportation

Beach material can be moved in four different ways. These are:

  • Solution - when minerals in rocks like chalk and limestone are dissolved in sea water and then carried in solution. The load is not visible.
  • Suspension - small particles such as silts and clays are suspended in the flow of the water.
  • Saltation - where small pieces of shingle or large sand grains are bounced along the sea bed.
  • Traction - where pebbles and larger material are rolled along the sea bed.

Sediment is carried by the waves along the coastline. The movement of the material is known as longshore drift. Waves approach the coast at an angle because of the direction of prevailing wind. The swash will carry the material towards the beach at an angle. The backwash then flows back to the sea, at 90° to the slope of the beach. The process repeats itself along the coast in this zigzag movement.

Waves approach a beach at an angle - determined by prevailing wind direction. Waves push rocks up the beach, roll back down and are pushed back up in a zig-zag pattern.