The Earth Spits Fire
||edHelper's suggested reading level:
||grades 9 to 10
||Flesch-Kincaid grade level:
||subduct, table-shaped, tabular, volcanism, subducts, solidify, batholiths, rift, composition, tremendous, hiccups, plutons, majority, igneous, fracture, intrusive
||Pacific Ring, Pacific Ocean, North America, South America, Aleutian Islands, North Pacific Ocean, Mid-Atlantic Ridge, North American
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The Earth Spits Fire
By Trista L. Pollard
1 The burps, grumbles, and hiccups that happen inside our planet produce the most fascinating changes on its surface. The Earth's crust with its shifting plates causes mountains to form, earthquakes to shake, and volcanoes to erupt.
2 Our planet's internal oven produces enough heat to move our tremendous tectonic plates. As these plates move, collide, and subduct, surrounding rock composition is altered. Combine this internal heat and moving plates with melting rock, and you have magma. Magma is the liquid rock that forms under the Earth's surface. Most of the time the rock in the mantle remains solid. This is due to the extreme pressure on the mantle from surrounding rocks in addition to very high temperature. However, there are occasions when mantle rock reaches its melting point. Once the mantle and crust melt, they form magma. Magma forms in three different ways. When a rock's temperature rises above the melting point of its minerals, then the rock is capable of melting. As you read earlier, the rock within the mantle is normally under extreme pressure. When this excess pressure is removed from the rocks, which are already heated above their melting point, the rocks will melt. The last way that magma forms involves fluids. When rock comes into contact with water, the melting point of its minerals may decrease. As a result, the rock will melt.
3 Activities that cause magma to move towards or onto the surface are categorized as volcanism. Magma has less density than the surrounding rock and this allows the magma to rise through the Earth's crust onto the surface. As magma travels toward the surface, it becomes larger as it picks up surrounding rock. The magma is extremely hot, so as it moves, it melts the surrounding rock. The new melted rock becomes part of the traveling magma. Think of it as a traveling magma convoy. Another way magma grows in size is when it enters the cracks of surrounding rocks. As the magma enters the cracks, large blocks of overlying rock break off and melt. Once the magma reaches the surface, it is referred to as lava. As with other shifts in our crust, lava is part of the mountain building process. This lava, as it flows through vents, may build up and form a cone of material. This material could in later years form mountains. These same vents or volcanoes also expel magma and gases into our atmosphere once they reach the surface.
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