Mountains are landforms that stick up high above the surrounding land. A mountain is a natural rise of the Earth’s surface that usually has a summit or top. The top of a mountain is called the summit, and the bottom is called the base. It is usually steeper and taller than a hill. Mountains cover one-fifth of the earth’s land surface and occur in 75 percent of the world’s countries.
Typically, a mountain will rise at least 1,000 feet above sea level with the highest mountain in the world, Mount Everest, rising 29,036 feet. Small mountains (below 1,000 feet) are usually called hills.
While some mountains are getting taller, you can’t see them grow. It takes a very, very long time for mountains to form.
Mountains are made when Earth’s crust is pushed up in big folds or forced up or down in blocks. Mountains form over the course of millions of years. They are not all the same. They are fold, block, dome, and volcanic mountains. Mountains are jagged because they are constantly eroded by the weather, which wears the rocky surface away.
There are five basic kinds of mountains:
1. Fold Mountains - Fold Mountains are the most common type of mountain. The world’s largest mountain ranges are Fold Mountains. These ranges were formed over millions of years. Fold Mountains are formed when two plates collide head on and their edges crumbled, much the same way as a piece of paper folds when pushed together.
The upward folds are known as anticlines, and the downward folds are synclines.
Examples of Fold Mountains include:
The Himalayan Mountains were formed when India crashed into Asia and pushed up the tallest mountain range on the continents.
In South America, the Andes Mountains were formed by the collision of the South American continental plate and the oceanic Pacific plate.
2. Fault-block Mountains – These Mountains form when faults or cracks in the earth’s crust force some materials or blocks of rock up and other down. Instead of the earth folding over, the earth’s crust fractures (pull apart). It breaks up into blocks or chunks. Sometimes these blocks of rock up and down, as they move apart and blocks of rock end up being stacked of one another.
Often fault-block Mountains have a steep front side and a sloping back side.
Examples of fault-block Mountains include:
3. Dome Mountains – Dome Mountains are the result of a great amount of melted rock (magma) pushing its way up under the earth crust. Without actually erupting onto the surface, the magma pushes up overlaying rock layers. At some point, the magma cools and forms hardened rock. The uplifted area created by rising magma is called a dome because of looking like the top half of a sphere (ball). The rock layers over the hardened magma are warped upward to form the dome. But the rock layers of the surrounding area remain flat.
As the dome is higher than its surroundings, erosion by wind and rain occurs from the top. This results in a circular mountain range. Domes that have been worn away in places form many separate peaks called Dome Mountains.
4. Volcanic Mountains – As the name suggests, volcanic mountains are formed by volcanoes. Volcanic Mountains are formed when molten rock (magma) deep within the earth, erupts, and piles upon the surface. Magma is called lava when it breaks through the earth’s crust. When the ash and lava cools, it builds a cone of rock. Rock and lava pile up, layer on top of layer.
Examples of volcanic mountains include:
5. Plateau Mountains (Erosion Mountains) – Plateau Mountains are not formed by internal activity. Instead, these mountains are formed by erosion. Plateaus are large flat areas that have been pushed above sea level by forces within the Earth or have been formed by layers of lava. The dictionary describes these as large areas of ‘high levels’ of flat land, over 600 meters above sea level. Plateau Mountains are often found near folded mountains. As the years pass, streams and rivers erode valleys through the plateau, leaving mountains standing between the valleys.
The mountains in New Zealand are examples of Plateau Mountains.
