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Geology of Shorelines

Shorelines can vary dramatically in their forms and compositions. Some shorelines are narrow with beaches formed from rounded or flattened cobbles and pebbles; some are wide and covered in a layer of sand or broken shell fragments; and still others are steep cliffs with no beach at all. The composition and structure of the beach will determine the potential effects of oil on the shoreline.

Oil tends to stick to mud and to the surfaces of cobbles and pebbles. It also flows downward in the spaces between cobbles, pebbles, and sand grains, and accumulates in lower layers of beach sediments. Oil that sticks to mud particles suspended in the water column and to cobbles and pebbles on the beach is exposed to the action of sunlight and waves, which helps it to degrade and makes it less hazardous to organisms that come into contact with it. Oil that sticks to rocks and pebbles can be wiped or washed off. Oil that flows onto sandy beaches, however, can "escape" downward into sand, making it difficult to clean up and reducing its ability to degrade.

Natural processes such as evaporation, oxidation, and biodegradation help to clean the shoreline. Physical methods such as wiping with sorbent materials, pressure washing, raking, and bulldozing can be used to assist these natural processes. Choosing the most effective yet potentially least damaging cleaning methods helps to assure that the natural systems of shorelines will be preserved and protected for future generations.


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