Rocks & The Rock Cycle7th Grade Science

Charles Leahy

What are the 3 main rock types found on the Earth?

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IgneousSedimentaryMetamorphic

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Igneous Rocks Most prevalent in Earth’s crust Intrusive - formed underground when magma (melted rock,

temps between 1,500 and 2,400 degrees F) cools Granite

Extrusive - formed above ground when lava (melted rock) erupts from volcanos and cools on the surface Basalt, Obsidian

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Formed by deposits of material on the Earth’s surface or within bodies of water (Sedimentation).

Sediment consists of small weathered particles of other rocks or the weathered shells of sea animals.

Wind and rain work on the exposed rock, particles are blown or washed away to new locations. Dead sea creatures float to the bottom of the ocean or lake.

Sediments pile up and become pressed together.The resulting weight compresses the sediments at the

bottom.Rock crystals and salts cement the sediments together,

creating sedimentary rock.Most prevalent type of rock on Earth’s surface.

Sedimentary Rocks

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• Sandstone • Limestone (sea

creatures)• Coal (from

peat)• Shale (from

clay)

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Metamorphic rocks have “morphed” into another kind of rock.

They were once igneous or sedimentary rock.Rocks deep in the earth (7 – 9 mi) are

exposed to tremendous heat (between 400 and 1,500 degrees F) and pressure.Sandstone -> QuartziteLimestone -> MarbleShale -> Slate

Metamorphic Rocks

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The Rock CycleWhat is a cycle?A model that describes the formation,

breakdown and reformation of a rock as a result of sedimentary, igneous and metamorphic processes.

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Closer look at the Rock Cycle

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Works Cited

Slide 2 http://www.herzen.spb.ru/alumni/1333366313Slide 3 http://www.open.edu/openlearn/science-maths-technology/science/geology/ro

ck-typesSlide 4 http://www.windows2universe.org/earth/geology/ig_magma.htmlhttp://www.mash.ie/documents/parts-of-a-volcano/

Slide 6 http://davidkanaga.blogspot.com/2011/07/sediments-and-sedimentary-rocks.htmlhttp://www.ehow.com/info_8639525_three-make-up-sedimentary-rock.html

Slide 7 http://www.americansouthwest.net/arizona/bill_williams_river/bwrocks_l.htmlSlide 8 http://www.learner.org/interactives/rockcycle/

Slide 9 http://www.abrighton.com/uploads/1/3/2/3/1323730/rock_cycle_drawing1.jpg