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| Sunday, 8 May 2005 |
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Junior Observer |  |
| News Business Features Editorial
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As high as a mountain
In simple words, a mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is higher than a hill and rises above 2000 feet. Covering around a fifth of the earth's surface, mountains exist in every continent. They occur more often in oceans than on land; some islands are the peaks of mountains rising out of the water. Mountains are symbols of stability. How do mountains form? They are created over long periods of time, by tremendous forces in the earth, with a steep top, usually shaped up to a peak or ridge. Mountains are formed by volcanism, erosion, and disturbances or an uplift in the earth's crust. Most geologists believe that the majority of mountains are formed by the geological forces, heat and pressure producing changes under the earth's crust, and movements in the earth's crust. They call this movement 'plate tectonics'. This theory sees the crust of the earth divided into a number of rigid plates that move about at the rate of a few centimetres an year. The term 'plate tectonics' describes this theory. It says that the Earth's crust is covered by a number of rigid plates that float on molten rock under the Earth's surface. As the plates slowly move, they sometimes collide. These collisions can cause earthquakes. The collisions can also cause large pieces of rock, or even part of the plate, to tower up into the air. This process can form mountains. The Earth's plates do not always push themselves up to form mountains. Sometimes, their movement causes magma to push between the cracks and erupt into the air. Magma is nothing more than molten rock. When it cools in the air after erupting, it becomes rock again. After many eruptions, a mountain will form from the cooled magma. There are five basic kinds of mountains: volcanic, fold, fault-block, dome, and erosion mountains. These different types of mountain names not only distinguish the physical characteristics of the mountains, but also how they were formed. Volcanic mountains are formed when molten rock, or magma deep within the earth, erupts, and piles upon the surface. These mountains are usually made of basalt and rhyolite. Volcanic mountain building takes place in subduction zones; this is where two of the earth's tectonic plates collide. Fold mountains, such as the Appalachian Mountains in the eastern United States, and the Alps in Switzerland, formed when two plates collided head on, and their edges crumbled. Fold mountains consist mainly of sedimentary rocks, like limestone and shale. Fault-block mountains consist of huge blocks of the earth's crust that have been tilted or pushed up along a fracture line called a fault. The Sierra in California, USA is an example of a fault-block mountain. It is created when a plate hits a fault and tips upside down, creating erosion and debris, which is at the base of the mountain. Fault-block mountains are found in places like Arizona and Nevada in the United States. Dome mountains such as the Black Hills in South Dakota, also in USA, form when tectonic forces lift the earth's crust into a broad bulge or dome.
Erosion mountains such as the Catskill Mountain in New York, result from erosion of a thick pile of sedimentary rock. This type of mountain is all that remains of a plateau after rivers or glaciers erode the plateau to form peaks and valleys. Did you know that mountains are full of various plant communities? If you climb from the base to the peak of a big mountain, you will pass through a number of different plant communities. The foothills may be covered in broad-leaved forests; higher up, coniferous trees like pines appear. As you climb higher, it gets colder and colder and the trees eventually thin out and disappear. The highest parts of the mountain support only sparse grasses and low-growing flowers. If the mountain is high enough, even this vegetation disappears and the peak is bare and rocky. *** The making of a mountain Here are some ways how mountains form: Two plates can press against each other until the land is lifted and folded over itself. One plate can push on top of another one. As one plate slides downward into the earth, it begins to melt. The melted rock rushes upward along cracks and weak spots, bursting out as fiery volcanoes. You can see a huge "ring of fire" where volcanoes circle the Pacific Ocean. Plates can stretch until they crack and slide, forming fault-block mountains. In the ocean, great underwater mountains are formed when plates spread away from one another, and melted rock pushes up through the gap. *** More mountain facts * The Himalayas are the world's tallest mountains. * The Andes, which runs for more than 4,900 miles, is the longest mountain range in the world. * Mauna Kea, Hawaii, with an elevation of 13,796 feet, is actually 32,000 feet tall from its start on the sea floor, making it the world's highest island peak from base to tip. * Mount Everest, part of the Himalayas, is the highest point on earth,
with a height of 29,023 feet. What many don't realise is that Mount
Everest is only one in this range of over 30 peaks that rise to over
24,000 feet. Also in this range is Kanchenjunga at 28,208 feet, Makalu at
27,766 feet, and Dhaulagiri at 26,810 feet. |
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| Politics | Produced by Lake House |
We know that our country is blessed with many beautiful mountains. But
have you ever wondered how these amazing landforms are made? And what a
flat, dull place the world would be without mountains? 
The dome is raised above its surroundings, so erosion will occur, and
as a result of erosion, peaks and valleys are formed. 
