Lesson Plan - Get It!
Do you recycle trash or old toys or clothing or furniture? Did you know the Earth recycles rocks? And you thought rocks just sort of sat there and didn't change! Read on to find out how amazing that is!
Do you recycle some of your trash?
Recycling trash means it is changed into something else. For example, recycled plastic can be used for bottles, furniture, toys, and even clothing!
Rocks and water are both recycled on Earth, but through different cycles.
If you have not yet studied, or need to review, the previous Related Lessons in our Rocks and Minerals series, find them in the right-hand sidebar.
Water is recycled through the water cycle, and rocks are recycled through the rock cycle. The rock cycle is constantly occurring on and below the surface of the Earth, as shown in the image below, provided by Siyavula Education:
Image, via flickr, is licensed under the Creative Commons Attribution 4.0 International (CC by 4.0) license.
What are the three types of rocks outlined in green in the image? What direction do the arrows show in the image above? Why do you think the arrows move in a circular way?
You will learn several vocabulary terms during this lesson. Make a quick vocab journal page on a sheet of paper so that you can capture each of the new words you learn. If you want to hear the new words pronounced, use Google to search the words, then use the audio to listen!
The three types of rocks are igneous, metamorphic, and sedimentary. All rocks fall into one of these three categories, and move through the rock cycle to change.
Magma is liquid crust found underground. It moves up towards the surface through volcanic and geologic activity. As it reaches the surface, magma cools down and solidifies into igneous rock.
Igneous rocks can form above or below ground. Igneous rocks above ground are called extrusive igneous rocks, and cool very quickly. When a rock cools very quickly, it makes it difficult to see the particles in the rock. Extrusive igneous rocks look the same throughout, like the rock below:
Intrusive igneous rocks form under Earth's surface, and cool slowly. During the cooling process, crystals form and are easily visible.
Granite is a great example of an intrusive igneous rock. Notice how clearly you can see the particles and crystals in the rock sample.
Igneous rock can be broken down during the processes of weathering and erosion to create small particles and sediment. Eventually, the sediment runs off and can build up in another location forming a sedimentary rock.
Sediments can build up in layers over time or become cemented together very quickly. Sedimentary rocks often have a sandy texture, and you can see the individual particles making up the rock.
Did you know that scientists find the most fossils in sedimentary rocks?
Fossils are visible in sedimentary rocks because the organism is able to be preserved as layers of sediment build up.
When sedimentary rocks are buried deep in the Earth, they can be exposed to high heat and pressure. Metamorphic rocks form when sedimentary or igneous rocks interact with heat and pressure under Earth's surface.
Metamorphic rocks with visible layers are called foliated. What type of rock forms foliated metamorphic rocks underground? Sedimentary rocks!
Non-foliated metamorphic rocks do not have visible layers; a great example is marble.
Marble is used in many homes as a material for countertops, because it is very visually appealing and durable.
Each type of rock can be broken down and turned into a new substance through the rock cycle. Metamorphic rocks can be weathered into small sediments that build into layers, forming a new sedimentary rock. Igneous rocks cool below Earth's surface and can become compacted into metamorphic rocks.
Draw a picture that represents the rock cycle without looking back at the image at the start of the lesson! Use arrows and labels to help explain your image.
In the Got It? section, you will review the rock cycle with an online presentation.