Essay Igneous Rocks And Rock Formation

1621 Words Nov 18th, 2016 7 Pages
While it may not seem like it, rocks and rock formation are a vital part of our day to day lives. Some geologists spend their lives studying these rocks to determine what rocks are in certain areas and how they formed. This information allows them to predict what is going to happen in the future as well as how the land got to be in the shape it is today. Experienced geologists can often know how a rock formed just by looking at it, but inexperienced geologists can easily do the same, if they know and keep in mind how certain types of rocks form. Igneous rocks have different textures, compositions, and formation locations which can be used to infer how and where a specific rock formed. With igneous rocks, texture does not refer to roughness or smoothness of the surface. “Texture” instead refers to crystal size, shape, and arrangement within the rock. Texture is determined by how long the lava or magma takes to cool (Rutzky). Rocks with larger crystals had longer cooling times, giving the hot minerals time to crystallize and grow. On the flip side, rocks with small crystals had very quick cooling times. Rocks with no crystals at all (such as obsidian) had the fastest cooling times, so the minerals had no time to form crystals (“Igneous Rock Textures”). Geologists use these textures to determine where igneous rocks formed and what minerals they are made up of. Textures can also show how much gas the magma contained before it hardened into rock. “Bubbly” rocks are formed from…

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