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The Rock CycleWhat is the rock cycle?
What exactly is a ROCK?• A rock is a naturally occurring solid. It is
a mixture of one or more minerals & organic matter.
• Rocks are always changing; this process of new rocks forming from old rocks is called the Rock Cycle
Are rocks useful?!Absolutely!• What were they used for? • Uses of rocks: Hammers &
other tools &…
arrowheads
knives
chertobsidian
Rocks were not only used to make tools…Rocks were also used to make
buildings, monuments & roads.
Limestone, a sedimentary rock was used to make
the pyramids
Washington Monument in D.C.-made of marble, granite & sandstone
What processes make & destroy rocks?
Geological processes such as erosion & deposition
influence the type of rock that is formed on Earth’s
surface
• Sediment: small particles (usually dirt) that was suspended in water and has settled to the bottom of water.
Erosion is the process of removing sediment from its original location. Usually carried away by water or air; (it is displaced)
Deposition is the sediment that is carried away (or displaced) by erosion, is dropped off in a new location.
Feeling the Heat & PressureSediment that is buried, can be squeezed by weight of
layers on top of it to form sedimentary rock.
When the pressure & temperature is high enough, the rock can change into metamorphic rock.
If the rock gets hot enough inside the earth, the rock melts. The melted rock becomes magma; which then cools & forms igneous rock.
Igneous Rock
Metamorphic Rock
Sedimentary Rock
Magma
melting
melting
Weathering
cooling
Weathering
sediment
Heat & pressure
Heat & pressure
Weathering
Compaction & cementation
Round & round the cycle goesBuried rock is brought to the Earth’s surface by
erosion & uplift (movement in the Earth, that brings rocks inside the Earth to the Earth’s surface).
On the Earth’s surface weathering, erosion & deposition occur.
How are rocks classified?• All rocks can be classified into 3 main classes of rock
based on how it is formed: – igneous, sedimentary & metamorphic
• Each rock class can be divided further; also by how they form. – Ex: Igneous rock can form beneath Earth’s surface &
other igneous rock can form above Earth’s surface
What is looked @ to classify rocks?
• Composition: the minerals that the rock
contains
• Texture: the size, shape & grain position that make up the rock
Calcite95%
Aragonite5%
Mineral Composition of Limestone
Calcite
Quartz35%
Biotite mica10%
Feldspar55%
Mineral Composition
of Granite
Rock Textures can VarySedimentary rock can be:
Medium grained
Fine grained Coarse grained
Varying Rock Textures Continued…Igneous Rock can be fine grained or coarse grained,
depending on how much time the magma has to cool.
Metamorphic rock can also be fine or coarse grained, depending on the amount of pressure & temperature the rock is exposed to. Rock Type Fine Grained Medium
GrainedCoarse Grained
Sedimentary X X XIgneous X X
Metamorphic X X
Why do we care to look @ the texture anyway?!
• For clues to tell us where & how the rock was formed
Sandstone
Basalt
Let’s see what we’ve learned!
Fill in the Blank:1. The minerals that a rock is made of
determine the __________ of that rock.
2. ______ is a naturally occurring, solid mixture of crystals of one of more
minerals.
Sediments are transported or moved from their original source by a
process called:
a) depositionb) erosion
c) upliftd) weathering
Describe 2 ways that rocks have been used by humans.
Explain the difference between composition & texture
Look @ the table below to answer the questionTexture Particle Size
Coarse grained > 2mmMedium grained 0.06 – 2 mm
Fine grained <0.06 mm
Sandstone is a type of sedimentary rock. If you had a sample of
sandstone that had an average particle size of 2 mm, what texture
would your sandstone have?
Power Point Presentation made by
Ms. Luck
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