Earth's Landforms

Third Grade

Getting the Idea

If you flew across the United States and looked down, what would you see? You would see flat land, tall mountains, and rolling hills. And you would see deep canyons, steep narrow valleys, and sloping wide valleys. These features of the land are called landforms.

Mountains, Volcanoes, and Islands

A mountain is a landform that rises steeply from the land around it. Some mountains are tall and rocky. Other mountains are rounded and covered with trees. Mountains form when Earth's surface gets pushed up or built up. There are two large group of mountains int he United States. One group is the Appalachian Mountains, which run through South Carolina. the other group is the Rocky Mountains, which are in the Western United States. The United States also has many smaller groups of mountains.

Some mountains form from volcanoes. A volcano is an opening in Earth;s surface from which hot, melted rock can flow out. Recall that melted rock that flows onto Earth's surface is called lava. Over time, the lava cools and hardens. It may build up so high that it forms a volcanic mountain. Mount St. Helens and Mount Rainier, in the state of Washington, formed this way.

An island is a landform with water all around it. the islands that make up the state of Hawaii are the tops of volcanic mountains sticking up out of the ocean. But not all islands are formed by volcanoes. Some islands are found in lakes. Others are found in the ocean near the seashore. these are called barrier islands.

Did You Know?

The highest point in South Carolina is at the top of Sassafras Mountain. it is about 1,085 meters high.

Valleys and Canyons

Another kind of landform is a valley. A valley is an area of low land that is found between high areas, such as mountains. Streams and rivers flow through most valleys.

A canyon is a valley that is narrow and deep, with steep, straight sides. A canyon is often formed by a river that flows swiftly over the land. It may take millions of years for a river to wear away the land to form a canyon. One example of this kind of landform is the Grand Canyon in Arizona

Plateaus and Caverns

The Grand Canyon was carved by a river in the Colorado Plateau. A plateau is a large, high area of flat land. It is higher than the land around it.

Water under the ground can carve landforms, too. A cavern is a large underground space that forms when water wears away rock.

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