Pebble, gravel and course-grain sand beaches are high risks areas in terms of profound contamination. Most hydrocarbons can easily enter gaps and flow so deep that it is practically impossible to remove them without seriously damaging the populations living within the sediment substrate.
Fine-grain sand beaches tend to retain oil on the surface, as the oil is
most likely too viscous to penetrate into the depths through the fine spaces.
Oil may accumulate along the
high tide mark and be covered over with a layer of clean sand of varying
Beach growth may cause layers of oil to be covered with sand, creating alternate layers. Buried oil is very problematic as the layers of oil may be uncovered by waves and swept away to then pollute other areas.