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Forces of nature shape our Earth. They destroy land. But they build new places and spaces too.

Forces of nature are always at work. Waves hit beaches. Winds blow sand. Water floods land. Ice breaks rock into pieces. Stones from cliffs and mountains fall to the ground.

These forces cause weathering. That is when rock breaks into bits.

Weathering breaks up mountains. The pieces then get carried off. This is called erosion. It wears land away.

Water and wind wear land down. Yet they build land up too. You can see these powers at work. Just look around the United States.

Bryce Canyon in Utah is a wonder. Huge rock poles called hoodoos rise up. They have odd shapes. How did they come to be? It took a long time.

Ancient rivers once bashed into mountains. The water carried off bits of land. Over time, the bits turned into rock.

An ocean flooded in. Sea animals' bones fell to the bottom. These too became rock. Then the ocean dried up. A mountain of mixed rock arose.

Nature worked hard on the new mountain. A river rushed in. The water washed softer rocks away. The harder rocks remained. The river shaped those rocks into hoodoos.

Rain splashed the hoodoos. It fell into cracks. In winter, the water turned to ice. The ice broke the cracks open. Rock fell to the ground.

Then wind chipped in. It blew the rock bits away. This still happens. The forces never stop.

Ice is a force. It breaks up mighty mountains. Some years, more snow falls than melts. That snow piles up. It forms huge sheets of ice. They are called glaciers. They do not stand still. They slide very slowly.

A moving glacier plows up the land. It knocks over trees. It also picks up sand and rocks along the way. This act is called plucking. Pieces stick to the bottom of the glacier. As it moves, the bits cut land. The edges chip into rocks.

Ice cuts mountains as it moves. It hacks holes. Glaciers carve valleys between mountains too. Sometimes two glaciers act together. They make tops of mountains look like horns.

All the time, the ice plucks rocks. It carries the rocks away. As it melts, it drops the rocks around. It leaves sand behind. This mix is called till. The till sometimes forms hills. It all happens very slowly. Glaciers can destroy mountains. But they also help to build land.

Weathering also works below ground. You can see how at Carlsbad Caverns National Park. It is in New Mexico. The park has at least 100 caves. Those are just the ones we know about!

Inside the caves, stone hooks hang from roofs. Rock straws grow from walls. Hoodoos stand tall on the floors. Dripping water made them.

Water mixed with dirt, rocks, and air. That made acid. Rivers carried it underground. It ate rock away. Drip by drip, it made rooms and tunnels.

Right now, streams cut through land. Waves wash rock. The forces are at work—even close to home. Just the wind in a yard can make changes. Watch how nature works around you. It may amaze you!

Article by Lesley J. MacDonald. Top-of-page photo by Yva Momatiuk & John Eastcott, Minden Pictures. "Earth Movers" appears on pages 18-23 of our October 2006 issue.