The Origin of Igneous Rocks

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History of Rock Worksheet

Write a 500- to 750-word explanation regarding the role of plate tectonics in the origin of igneous rocks.

Igneous rocks can come from two hot liquid like materials, which are lava and magma, these to substances are a lot alike, magma is what lava is before it is taken to the Earth's surface by a volcano eruption. These substances being such a large part of the forming of Igneous rocks is where the rock gets its name, the word igneous comes from the word ignis, which is the Latin word for fire. Magma and Lava are a consistency like molten metal and they carry crystallized minerals and are hot enough to change existing rocks forms. Igneous rocks are created in three places. The first is where the lithospheric plates pull apart making a gap in the at the ridges under the ocean. The second is where the continental crust is forced together. The third is where the plates come together. As the lava or magma moves they collect different minerals and these minerals begin to crystallize as the lava or magma cools. The speed of the cooling process helps to determine the physical characteristics of the rocks. With the movement and the new minerals that come this will change the rock. There are two types of Igneous rocks. The first kind of Igneous rock is Extrusive rock, which is formed when magma escapes through the where the plates meet, these rocks cool very quickly some in a matter of seconds which makes their grains very small called the Aphanitic texture. The second kind of Igneous rock is Intrusive rock, which is made underneath the Earth's surface which makes it cool very slowly some take thousands of years, which makes larger size grains called Phanertic texture. The classification of each rock is based on the minerals that it is made up of, some of the common minerals found in Igneous rocks are olivine, mica, feldspar, quartz, and pyoxenes. The most well known Igneous frock is Granite, which is also the most commonly used Igneous...
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