Marine Erosion

Constructive and destructive
Marine erosional processes

Marine Erosional Processes

Hydraulic Action
Occurs due to the force of air and water acting in joints and cracks. It occurs as the waves breaks onto cliffs, any air trapped in cracks of the cliff will be under great pressure. As the waves retreats, the pressure is released with explosive force and the rocks will weaken and will be shattered by the storm waves.
Corrasion or Abrasion
Whereby a breaking waves hurls pebbles and shingles against a coast and erodes it.
Wearing away of the load itself. Gradual reduction in the size of the loads as it crashes with other particles.
Solution or Corrosion
Chemical erosion in chalk and limestone rocks where acidic water dissolve rock.
Refer to: http://www.geographyalltheway.com/in/gcse-coasts/wave_processes.htm

Wave Refraction and Long Shore Drift
Formation of cave, arch, stack and stump
Longshore drift explained

Marine Transportation Processes
Large boulders and pebbles are carried along the sea bed
Small pebbles and stones are bounced or roll along the bed
Fine light materials are suspended in the sea water
Fine light materials are dissolved in the sea water, involves chemical change

Overview of coastal landforms
Spit Formation
Battle between erosion and depositional
forces- coastal landform

Coastal Vegetation in Salt Marshes and Sand Dunes
Adaptation mechanism
Halophytes (salt tolerant)
Have a number of ways to cope with the daily changes in the levels of salinity, submergence by water and rapidly shifting sediments.

Able to tolerate the waterlogged situation two times a day during high tides.
Deep root to anchor the plant in the mud.

Ability to extract nitrogen directly from the air.

Example: Mangrove vegetation in tropics and sub tropics.
Xerophyte (drought resistant)
Condition on the foreshore is harsh, saline, windy and arid, due to the presence of the permeable sand.
Two most common species: Sea couch and Marram grass

Sea couch store water in its succulent leaves

Marram has deep tap roots

Salt Marshes

Coastal Management
Hard Engineering* Building artificial structures such as sea wall, Groynes, rock armor aimed at controlling natural processes
  • Trying to win over the forces of nature
  • Immediate solution to protect high value properties
  • Very costly and may have adverse environmental impact

Soft Engineering* A suitable approach to manage the coast without using artificial structure. For example, beach nourishment
  • Try to fit in and work with the natural processes
  • Often low maintenance cost - both economically and environmentally
  • Managed retreat or coastal realignment:
    • Allowing controlled flooding of low lying coastal areas where the value of land is low

Cliff side erosion: need of coastal management
Fun video on coastal management

Coral Reefs

Click here to see National Geographic coverage on Great Barrier Reef

The world of Coral Reef-
Great Barrier Reef,
National Geographic coverage
on Great Barrier reef
bio diversity
Coral Bleaching
Five largest Coral Reefs
of the world

National Geographic:
What are coral reefs?
Coral Gardening: Geo-engineering
to counter balance bleaching
Underwater coral reef Tourism
Hotel poseidon

Fun Learning

Try out this Millionaire game on Marine process
Destructive strom waves and
life risking surfing