Getting the Idea
Mountains, Volcanoes, and Islands
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?
Valleys and Canyons
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
Water under the ground can carve landforms, too. A cavern is a large underground space that forms when water wears away rock.