In geological sciences, sedimentation is the process of accumulating sediments, or dirt, on the reef. It is a natural phenomenon that results from land and reef erosion. Broadly defined, it also encompasses glacial ice deposits and accumulation of materials due to gravity, such as talus deposits and rock debris collection at the base of cliffs.
Soil decomposition, plant decomposition, animal decomposition and bedrock erosion are natural sources of sediments transported to the oceans. Sediments often add nutrients to the soil. Natural sediment mobilization helps develop and maintain coastal habitats, such as mangroves, coral reefs, estuaries, lagoons and wetlands. However, many human activities often alter the process of sedimentation and erosion. High sedimentation destroys corals when sediments land directly on top of corals, smothering the corals. Corals are not capable of removing sediments, because they cannot move. Sedimentation is sometimes detrimental to corals, mainly because it affects water clarity and makes the water cloudy or turbid. When there is high turbidity, the amount of light that reaches the corals is considerably decreased. With lesser light, corals find it difficult to photosynthesize. Human activities are major culprits in the increase of sedimentation rates along many coastline areas. These activities are mainly related to poor land management practices, such as unregulated use of off-road vehicles and poor urban development.