Rock and soil do not stay in one place forever. Sediment is the particulate material—sand, silt, clay, gravel—that is transported and deposited by water, wind, or ice. It may also include organic matter and chemical precipitates.

Rivers carry sediment from eroding uplands to depositional basins. Wind moves sand into dunes. Glaciers transport and dump unsorted debris. Over time, accumulated sediment can lithify into sedimentary rock, recording past environments in its layers.

Sediment supply builds deltas, beaches, and floodplains. Too much sediment can choke reservoirs and coral reefs; too little can cause coastal erosion. Managing sediment is therefore a practical concern for engineers and environmental managers. Geologists read sedimentary deposits to reconstruct Earth’s history.

• Material transported and deposited by natural agents
• Includes sand, silt, clay, and gravel
• Builds landforms such as deltas and dunes
• Source material for sedimentary rocks