Igneous Rock
Igneous rocks form from the cooling of molten material in the Earth’s crust. The definition of igneous means heat. In this case, igneous rocks are formed when molten material cools down either underneath the Earth crust to form plutonic igneous rocks or on the surface of the Earth to form volcanic igneous rocks. Molten material is found below the Earth's crust and is normally subjected to extreme pressure and temperatures. Because of the high temperatures and pressure changes, the molten material sometimes shoots up to the surface in the form of a volcanic eruption and then it cools down to form a volcanic or extrusive igneous rock. Alternatively, some of the molten material may cool underneath the Earth's surface very slowly to form a plutonic or intrusive igneous rock. This is because of the extreme heat levels and changes in pressure that an igneous rock does not contain organic matter or fossils. The molten materials interlock and crystallize as the molten material cools and forms solid an igneous rock. There are more than 700 known types of igneous rock and most of them are formed under the Earth’s crust since volcanic eruptions are do not happen often. On this basis, we are going to look at the commonly identified types of igneous rocks, both intrusive and extrusive. They include: granite, gabbro, basalt, diorite, andesite, obsidian, pegmatite, and pumice. Granite rocks are the light-colored and coarse types of igneous rocks. Gabbros are the dark-colored and coarse types of igneous rocks. Basalts are the dark-grey colored and fine-grained igneous rocks. Diorites are the coarse-grained igneous rocks just like the granite and gabbros. Andesites are grey-colored and fine-grained type of igneous rocks. Obsidians are the dark-colored and smooth type of igneous rocks, just like the photo up above. Pegmatite is a form of igneous rock consisting of extremely coarse granite, results from the crystallization of molten material, which is rich in rare elements. Pumice is a light-colored, vesicular, and porous, like igneous rock that forms as a resulting of very fast solidification of molten material.
About the Prezi
You will learn about the The three main types of rock, igneous, metamorphic, and sedimentary rock. You will also learn how each of these rocks form. Lastly, you will learn
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Metamorphic Rock
Metamorphic rocks have been changed over time by extreme pressure and heat. Metamorphic rocks can be formed by pressure deep under the Earth's crust, from the extreme heat caused by molten material or by the intense collisions of the plate tectonics. Uplift and erosion help bring metamorphic rock to the Earth's surface. Examples of metamorphic rocks include anthracite, marble, slate, granulite, gneiss, and schist. Anthracite is a type of coal with a huge carbon count, few impurities and with a high luster, meaning it looks shiny. Marble is a metamorphic rock that is formed from sedimentary rock. Slate is a metamorphic rock that forms from the sedimentary rock mudstone. Granulite is a metamorphic rock that is forms from the igneous rock basalt.
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Rocks & How They Form
https://web.csulb.edu/depts/geology/facultypages/bperry/Metamorphic%20Rocks%20Tour/INTRODUCTION.htm
Sedimentary Rock
Sedimentary rock are formed when sediment is deposited over time, usually as layers at the bottom of lakes and oceans. This sediment can include minerals, small pieces of plant, and other organic matter. The sediment is squeezed together over a long period of time before consolidating into solid layers of sedimentary rock. Sedimentary rock forms layers called strata which can often be seen in exposed cliffs. Sedimentary rock covers the majority of the Earth's rocky surface but only make up a small percentage of the Earth’s crust compared to metamorphic rock and igneous rock types. Examples of sedimentary rocks include limestone, sandstone, mudstone, chalk, coal, and flint. Limestone forms the metamorphic rock marble when exposed to extreme heat and pressure over time, known as metamorphism. The sedimentary rock sandstone forms the metamorphic rock quartzite. Mudstone forms the metamorphic rocks slate. Chalk is a smooth, white form of limestone. Flint is a rough, sedimentary form of the mineral quartz.
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