Final answer:
When a river reaches the ocean or a large lake, the sediments settle at the bottom and build deltas or estuarine areas. These sediments can eventually form sedimentary rocks. During sedimentation, floc particles settle to the bottom of the water supply.
Step-by-step explanation:
When a river reaches the ocean or a large lake, the water typically slows dramatically and any silt in the river water will settle. Rivers with high silt content discharging into oceans with minimal currents and wave action will build deltas, low-elevation areas of sand and mud, as the silt settles onto the ocean bottom. Rivers with low silt content or in areas where ocean currents or wave action are high create estuarine areas where the fresh water and salt water mix.
Sedimentary rocks (layered rocks) are made by the deposition of particles carried in air or water and by the precipitation of chemicals dissolved in water. These particles and chemicals come from the weathering (breaking apart in place) and erosion (carrying away and breaking apart while moving) of rocks on the Earth's surface. Boulders, rocks, gravel, sand, silt, clay, and mud are carried by water currents in streams, rivers, lakes, and oceans. These particles are deposited in stream beds, shores, lake and ocean bottoms, and deltas where rivers empty into lakes and oceans. These particles are cemented together and hardened to form the sedimentary rocks called conglomerate, sandstone, siltstone, shale or claystone, and mudstone.
During sedimentation, floc settles to the bottom of the water supply, due to its weight. This settling process is called sedimentation. The floc particles are then removed from the bottom of the basins.