Rock Cycle Unit
Presentation
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Science
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7th - 8th Grade
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Hard
Joseph Anderson
FREE Resource
18 Slides • 15 Questions
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Intro to the Rock Cycle
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Open Ended
Look at the picture of the 3 types of rocks. What is one similarity OR one difference between the rocks?
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Minerals and Rocks
Mineral: a solid that is formed naturally in the earth and normally has a crystal structure
Rock: a solid that is made up of one or more minerals
Minerals are the "building blocks" of rocks.
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Types of Rocks
Rocks are classified into 3 categories, based on how they are formed
Does anyone know what the three categories are?
Answer: igneous, metamorphic, and sedimentary
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Multiple Choice
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1. Igneous Rocks
Igneous rocks are formed by magma/lava.
When a volcano erupts, it spews out hot molten rock called lava. Eventually the lava will cool down and become solid. This forms an extrusive igneous rock.
Igneous rock can also form as magma cools below earth's surface. These are called intrusive igneous rocks.
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2. Sedimentary Rocks
Sedimentary rocks are formed by years of sediment (small pieces of rocks/minerals) compacting together and becoming hard.
A stream or river will carry lots of sediments to a larger body of water. These pieces will settle at the bottom and over a really long time (perhaps millions of years), they will form into solid rock.
Some examples of sedimentary rocks are shale, limestone, and sandstone.
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3. Metamorphic Rocks
Metamorphic rocks are formed by heat and pressure.
They are generally found inside the Earth's crust.
Metamorphic rocks are often made from other types of rock. For example, shale, a sedimentary rock, can be changed into a metamorphic rock such as slate.
Other examples of metamorphic rocks include marble and anthracite.
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Multiple Choice
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Multiple Choice
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The Rock Cycle
The rock cycle is how natural processes (weathering, erosion, deposition, heat, and pressure) can cause rocks to change from one type to another.
The process is very slow but is constant.
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Weathering and Erosion
Rocks on the surface of the earth are constantly being broken down by wind and water.
The result of all this? Large rocks are worn down to smaller sediments.
When the sediments are broken off a rock and stay in the same area, it is called weathering.
When the sediments are carried somewhere else, it is called erosion.
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Multiple Choice
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Multiple Choice
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Multiple Choice
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Deposition
Sediments are carried away by wind or by rain, streams, rivers, and oceans. As rivers get deeper or flow into the ocean, their current slows down, and the rock particles (mixed with soil) sink and become a layer of sediment. This is called deposition.
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Compaction/Cementation
As the layers of sediment stack up (above water or below), the weight and pressure compacts (squashes down) the bottom layers. This is called compaction and cementation.
After years of this, the sediment turns into sedimentary rock.
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Multiple Choice
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Metamorphism
Metamorphism: Over very long periods of time, sedimentary or igneous rocks end up buried deep underground, usually because of the movement of tectonic plates. While underground, these rocks are exposed to high heat and pressure, turning them into metamorphic rock.
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Multiple Choice
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Melting and Crystallization
Melting: Metamorphic rocks underground melt to become magma. When a volcano erupts, magma flows out of it.
Crystallization of magma: As the lava cools it hardens and becomes igneous rock.
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Multiple Choice
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Multiple Choice
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Intro to the Rock Cycle
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