Types of rocks

Parker Heiss

Mrs.Troester

English 8

10 April 2017 

For years, people have not known about the three main types of rocks. In this essay my goal is for you to come out of the cave of darkness and into the sunshine of knowledge. Lots of people out there don’t know about them. They are very interesting and there is so much to learn about them. There are three types, metamorphic, sedimentary, and igneous. They are very interesting and they will take you on a magical adventure learning.

            First, metamorphic rocks are very interesting and they are made by heat formation. The rocks are made by very high heat compression deep in the earth. The word metamorphic also means change by heat form, which is very interesting because, they are made so far in the earth. It is very hot down there. Most people think that the heat is the worst part but they are wrong, it is actually the pressure of everything on top of them. It is so much pressure and heat that the texture and size are altered. Some of the things that come from this are marble, hornfels, and slate.

            Next, igneous are made from magma cooling. Lava cools very quickly at first and forms a thin crust that insulates the interior of the lava flow. As a result, basaltic lava flows can form crusts that are thick enough to walk on in 10-15 minutes but the flow itself can take several months to cool! It often times makes crystals. When a volcano erupts the lava can get stuck in a crevice it will cool there and that is an example of a rock. It can sometimes make glass. Granite, pumice, and obsidian are examples.

            Last, sedimentary rocks are made from sediment deposited by water air. This type of rocks is mainly made in earth’s surface and in bodies of water. There is a good chance if you find this rock it is made from plant or animals fossils. Some examples of them are coal, limestone, quartz, iron ore, sandstone, and shale are examples.

            Thus, rocks are very interesting and take you on an adventure. They are very vital to this word and without them we would not have nearly the stuff we do today. Humans are very smart and with this our brains can grow. Thank you for reading.