What is a mountain? A mountain is an area of land that rises to a great height. Mountains are all around us. They are on every continent. They are even under the oceans.
Mountains are made in different ways. Some mountains are made by volcanoes. Others are formed when the earth's crust folds over. Some mountains are even made when large rock blocks slide away from each other. Each way forms a different type of mountain.
The earth's crust is divided into plates. The continents and ocean floors are on these plates. The plates slowly move around, pulling apart or pushing together. We cannot see these drifting movements because they happen very slowly. These movements make mountains.
Mountains created by volcanoes can appear quickly. Melted rock erupts from cracks in the earth's crust. The melted rock, or lava, forms layers of rock as it cools. All of these layers make a mountain. Mount St. Helens is a mountain that was created by a volcano.
Folded mountains are made when two plates push together. The pressure folds the rock. The earth's crust bends and buckles, pushing the rock up. The Appalachian Mountains are folded mountains.
Block mountains are made when plates push together but do not bend. Instead, the crust fractures. A rock block slips up, and another slips down. The rock that slips up makes a mountain. The Tetons are block mountains.
Dome mountains are made when melted rock called magma cannot come out of the earth. Instead, it pushes and pushes against the rock on top. The rock bends and forms a dome on the surface. The Black Hills in South Dakota are dome mountains.
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