Which Sediments Settle Closest to Shore When a River Meets the Ocean?

When a river flows into the ocean, its velocity drops dramatically. This slowdown causes the heaviest, coarsest sediments—like gravel and coarse sand—to settle out first, right near the shoreline. Finer particles such as silt and clay remain suspended longer and are carried farther offshore before they finally deposit. This natural sorting process creates distinct zones of sediment size radiating from the river mouth.