Deposition

Deposition happens when wind, water, or ice drops the material it has been carrying. After rocks are broken by weathering and moved by erosion, they have to land somewhere. When the moving force slows down, it drops the sediment. Over time, deposition builds up new landforms.

How Deposition Works

Fast-moving water can carry heavy rocks and sand. When the water slows down, it drops the heaviest pieces first. The lightest pieces settle last. This is why you find big rocks upstream and fine sand at river mouths. Wind works the same way. When wind slows, it drops sand and dust.

Landforms from Deposition

Deposition creates many landforms. River deltas form where rivers meet the sea and drop their sediment. Sand dunes form when wind deposits sand in one place. Beaches are made from sediment deposited by ocean waves. Glaciers leave behind hills of rock and dirt when they melt.

Fun Facts

• The Mississippi River Delta was built from millions of tons of sediment deposited over thousands of years.
• Sand dunes can move across a desert as wind picks up sand from one side and deposits it on the other.
• Some of the world's best farmland is found on river floodplains where nutrient-rich sediment has been deposited.

Did You Know?

The Nile River in Egypt has been depositing rich soil along its banks for thousands of years. Ancient Egyptians relied on this deposited soil to grow their crops and build one of the world's greatest civilizations!