Sedimentation is the act of depositing sediment. This process can destroy sedimentary structures that were present upon deposition of the sediment. These become concentrated in the surface film and in marine sediment, especially estuarine mud. As water flows through the swamp, nutrients, sediment and pollutants are naturally filtered out. The EPA found no contamination in water, soil, sediment, or plant samples. Alluvial rivers with intense accumulations of sediment tend to this behavior. Abrasion produces fine sediment, termed glacial flour. Triclosan favors anaerobic conditions which is typical in soil and sediment. Driskill Mountain is a landform created by the erosion of unlithified Paleogene sediment. Subsidence can also occur due to sediment settling. The widespread sea ice prevents the deposition of fresh carbonates in ocean sediment. Streams can carry sediment, or alluvium. These lakes had a multitude of impacts on the river beyond sediment retention. In hillslope sediment transport, a variety of processes move regolith downslope. The lithostatic pressure in the rock increases due to the weight of the overlying sediment.