How Wind, Water, and Ice Shape Land

By the end of this lesson, you will be able to explain and model how wind, water, and ice change Earth's surface to make landforms like deltas, canyons, and sand dunes.

Think about a rainy day in Texas. Water runs across a dirt yard and carves little channels in the ground. At the bottom of the slope, the muddy water slows down and drops the dirt in a small fan shape. You just watched two important processes. Erosion is when wind, water, or ice picks up rock and soil and carries it away. Deposition is when that material is dropped in a new place.

Those same two processes build big landforms, just much more slowly. A river carrying water and sand rubs against the rock below it year after year. Little by little, it cuts a deep, steep valley called a canyon. Palo Duro Canyon in the Texas Panhandle was carved this way by a river over a very long time.

Now think about where a river ends. When the Rio Grande reaches the Gulf, the water slows down and cannot carry its load anymore. The sand and mud settle at the mouth of the river and pile up into new land called a delta. Deltas are usually flat and shaped a little like a triangle or a fan.

Wind builds landforms too. In West Texas, strong wind pushes sand across the ground until something slows it down. The sand piles up into hills called sand dunes, and the wind keeps moving them slowly across the desert. Ice can do this work as well. Heavy sheets of ice scrape rock as they slide, then leave piles of rock and soil behind when they melt.

Try it: If a fast river suddenly slows down and spreads out when it reaches a lake, would it carve the land away or drop its sand and build new land?