The Living World
21 Topics | 21 Quizzes

Coastal Processes: Transportation

Transportation, as the name implies, is the process of the ocean moving material. Material can be introduced into the sea in a number of ways, including erosion from rock and input from rivers. Also, destructive waves contribute to the erosion and movement of this material along the coast.

Once the material is in the water it is moved in several ways: 

  • Traction: Larger, heavier materials such as pebbles are dragged along the sea floor
  • Saltation: Small but heavier materials, such as larger grains of sand or shingle, are bounced along the seabed
  • Suspension: Small, fine materials or particles are held in the flow of water
  • Solution: Minerals from rocks are dissolved in seawater and carried in solution with no visible load

The sediment is then carried by the waves and deposited along the coastline through a process known as Longshore Drift. Longshore Drift is one of the main processes behind the transportation and deposition along coastlines, so it’s important for you to understand how it works. 

Longshore Drift

Longshore Drift operates somewhat like a conveyor belt: it’s an almost mechanical process that moves and deposits material along the coastline.

Waves approach the beach at an angle because of the prevailing wind. As the waves break, the swash carries material up the beach at that same angle. The backwash then flows back to the sea naturally, due to gravity, following the slope of the beach. This process repeats in a zigzag pattern along the coastline and gradually transforms the shape of the coast over time.

Various factors, including the type of shoreline, wave energy, wind direction and even human interventions, can influence the intensity and direction of longshore drift.

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