Igneous Rocks: The Three Different Types Of The Earth

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Rocks will start within one form and change through the course of time into another rock type. There are three different types of rocks in the world: igneous, sedimentary, and metamorphic. Each type of rock is formed in its own unique way. First, igneous rocks can be intrusive or extrusive. Intrusive igneous rocks, also known as plutonic rocks, are formed inside earth's crust. Molten rock rises and fills openings or melts overlaying rocks. This eventually hardens creating an intrusive igneous rock. An extrusive igneous rock, or volcanic rock, is created by magma rising the earth's surface. Magma is known as lava when it reaches the surface. After the magma reaches the surface, it runs down and cools. As the lava cools it hardens and becomes…show more content…
Weathered pieces of pre-existing rocks and organic debris make up a sedimentary rock. This is the type of rock that fossils are found in. Sedimentary rocks are classified into three separate groups: clastic, chemical, or organic. Clasitic rocks are classified by their grain size. Shale, siltstone, sandstone, and conglomerate. Mineral solutions form chemical sedimentary rocks. They are classified by thier mineral composition. Rock salt, rock gypsum, and crystalline limestone are common chemical sedimentary rocks. Organic sedimentary rocks are made up of organically derived sediments. These sediments are normally made up of body parts from plants and animals. Examples of organic sedimentary rocks include many limestones and coal. Organic rocks are classified by geologists by composition. Sedimentary rocks give information of the place it was deposited. Geologists use this insight to help predict the history of the area, as well as look for economically valuable minerals and rocks…show more content…
They are made up of either igneous or sedimentary rocks. The rocks are changed due to the intense heat from magma and the fierce pressure from shifting tectonic plates. Even though the rocks get very hot, they do not melt. If these rocks did melt it would result in the formation of an igneous rock instead of a metamorphic rock. Metamorphic alteration causes the texture and mineral composition to change. Recrystallization is the process of the formation of a new texture. Metamorphic rocks are usually classified as either regional or thermal. Regional metamorphic rocks are mostly formed by pressure instead of heat. Different types of rocks are created based on the amount of pressure. The higher the pressure, the more drastic the change. The temperature increases the deeper a rock is. This gives good possibilities for more diverse changes. Examples of regional metamorphic rocks include schist and gneiss. Thermal metamorphic rocks, also known as contact metamorphic rocks, are formed by extreme heat along with quite a bit of pressure. The pressure pushes the molten rock against the Earth's surface, causing it to recrystallize. Examples of thermal metamorphic rocks are marble and sandstone
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