What is the Rock Cycle?
THE ROCK
CYCLE
The Rock Cycle
 Defined: The process by which all rocks on
Earth are formed and how basic Earth
materials are recycled over time
 Note: A very, very long time
The Rock Cycle
Igneous
Rock
Sedimentary
Rock
Metamorphic Rock
Three main types of rock on
Earth
 Igneous Rock: Forms from molten rock that cools
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and hardens either above or below Earth surface
Two Types: Intrusive/Extrusive
Sedimentary Rock: formed either by pieces of rock
being bound together or by chemical precipitation
Two types: Clastic/Non clastic
Metamorphic Rock: Form when any type of rock is
altered by the effects of heat, pressure, or chemical
action
Two Types: Foliated/ unfoliated
Watch the Video and fill in
this Chart!
 http://www.youtube.com/watch?v=U7YQ5vwaL98
Why does the Rock Cycle even exist?
 DENSITY (again)
 When rock is heated up and melted inside the
Earth, it becomes hot liquid (magma) hot
liquids are less dense then solid rock.
 The magma moves up through any cracks or
openings (volcanoes, fissures) until it reaches
the surfaces. Then spreads out, cools, and
turns solid.
Why does the Rock Cycle even
exist? Cont’d
 After rock is formed, one of two things will
occur.
 1. Rock will begin to erode into small
sediments and settle somewhere else on
Earth’s surface (sedimentary)
 2. That rock will cool, turn solid, and become
more dense, where over a long time period,
will begin to sink. 
 Thus causing a cycle!
Next time we will introduce Igneous
Rocks, their formation, and types
IGNEOUS ROCKS
 Igneous Rock: Forms from molten rock that
cools and hardens either above or below
Earth surface.
 Igneous rocks are often defined by texture
and chemical composition.
Igneous Rocks
 Identification of igneous rocks factors
 Texture: The feel, appearance, or consistency
of a surface or a substance. (Simply what the
rock type looks and feels like)
 mineral and chemical composition:
 What minerals does the rock consist of?
Igneous Rocks
 Igneous Rocks are made from volcanic
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activity and form when magma or lava cools
Magma: Hot molten material INSIDE of the
Earth’s surface
Lava: Hot molten material OUTSIDE of the
Earth’s surface
MAJOR ELEMENTS PRESENT IN MAGMA
Oxygen, Aluminum, Iron, Magnesium,
Calcium, Potassium, and Sodium.
Igneous Rocks by Physical
and Chemical Characteristics
 Intrusive Igneous Rocks:
 Course-grained igneous rock that cools
slowly beneath the Earth’s surface.
 Extrusive Igneous Rocks
 Fine-grained igneous rocks that cool quickly
on Earths surface overnight
Intrusive Igneous Rock

Cools and turns solid very, very slowly below the Earths surface. Typically
have large crystals present in the rock due to the slow cooling process
.
Intrusive Igneous Rocks
Granite is a coarse-grained, light
colored, intrusive igneous rock that
contains mainly quartz and feldspar
minerals. The specimen above is
about two inches (five centimeters)
across.
Diorite is a coarse-grained, intrusive igneous
rock that contains a mixture of feldspar,
pyroxene, hornblende and sometimes quartz.
The specimen shown above is about two
inches (five centimeters) across.
Extrusive Igneous Rocks
Fined grained (smooth) rock that cools quickly
on Earth's surface. Cools quickly due to
exposure to the atmosphere, interaction with
water, etc.
Extrusive Igneous Rocks
Basalt is a fine-grained, dark-colored
extrusive igneous rock composed mainly of
plagioclase and pyroxene. The specimen
shown is about two inches (five
centimeters) across.
Hawaiian Islands
Obsidian is a dark-colored volcanic glass that
forms from the very rapid cooling of molten
rock material. It cools so rapidly that crystals
do not form. The specimen shown above is
about two inches (five centimeters) across.
Identifying Igneous Rock by
Color
 FELSIC and MAFIC Igneous Rock
 Felsic: Light-colored Igneous Rocks. They are
light in color due the minerals Feldspar and
Silica being present in the mineral
 Mafic: Igneous Rocks that are dark in color
due to the presence of Magnesium and Iron
Overview of Identification
of Igneous Rocks
IDENTIFICATION
DEFINITION
EXAMPLES
Intrusive
Cools and turns solid very, very slowly
below the Earths surface. Typically
have large crystals present in the rock
due to the slow cooling process.
Granite
Diorite
Extrusive
Fined grained (smooth) rock that cools
quickly on Earth's surface
Basalt
Obsidian
Mafic
Igneous Rocks that are dark in color
due to the presence of Magnesium and
Iron
Obsidian
Basalt
Felsic
Light-colored Igneous Rocks. They are
light in color due the minerals Feldspar
and Silica being present in the mineral
Granite
Diorite
Regents Scheme for Identifying Igneous Rocks
Sedimentary Rocks
2nd most Abundant type
of rock in the Earth
system.
Sedimentary Rocks
 Defined:
 Rocks formed either by rock fragments or
organic matter being bound together or by
chemical precipitation.
Formation of Sedimentary
Rock
 Very cool process 
 Sedimentary rocks formed over millions of years.
The form through a variety of processes
beginning with Weathering and Erosion
 Step one.
 Weathering: General process where rocks are
broken down at Earths surface to produce
sediment particles
 Erosion: The process of individual sediments
being carried down hill.
Two Types of Weathering
 Physical and Chemical
 Physical: occurs when solid rock is broken
into smaller pieces by mechanical process
that does not change the chemicals in the
rock
 Chemical: Occurs when the minerals in a rock
are chemical altered or disolved
Examples of physical
weathering
Examples of Chemical
Weathering
Formation of Sedimentary
Rock
Weathering occurs when
either rain, Ice, wind, or
water, breaks down solid rock
over time into small,
individual sediments
Erosion: Sediments are
carried from high energy
to low energy areas.
Typically occurs by water
transporting the
sediment down hill. Also
by wind.
Transportation and
Deposition
 Step two:
 Transportation: currents of wind and water or
the moving ice of glaciers transport sediment to
new locations down hill or down stream.
 Deposition: Occurs when sediment particles
settle out as wind dies down, water currents
slow, or glacier edges melt.
Step 3: Compaction and
Cementation
 Compaction: Process of sediments building
up in layers on top of each other over time
 Cementation: hardening of clastic sediments
by the precipitation of mineral matter in the
pore spaces. It is the last stage in the
formation of a sedimentary rock.
Two Main Types of
sedimentary Rock
 Clastic or Non-Clastic
 Clastic Sedimentary Rock-Made of small pieces
of other types of rocks (igneous, metamorphic,
sedimentary). And are cemented together after
deposition.
 Non-clastic sedimentary rock: Non-clastic
sedimentary rocks form from the
precipitation (Precipitation is the separating of
a solid from a solution) of minerals from ocean
water or from the breakdown of the shells and
bones of sea creatures.
Examples of Clastic Sedimentary Rock
Sandstone: a clastic sedimentary rock
made up mainly of sand-size
weathering debris
Conglomerate: a clastic sedimentary
rock that contains large rounded clasts.
generally filled with smaller particles
and/or a chemical cement that binds
the rock together.
Shale: a fine-grained sedimentary
rock that forms from the compaction of
silt and clay-size mineral particles that
we commonly call "mud".
Examples of Non- Clastic
Limestone is a sedimentary rock composed
primarily of calcium carbonate (CaCO3) in the
form of the mineral calcite. It most commonly
forms in clear, warm, shallow marine waters. It
is usually an organic sedimentary rock that
forms from the accumulation of shell, coral,
algal and fecal debris. It can also be a chemical
sedimentary rock formed by the precipitation
of calcium carbonate from lake or ocean
water.
Rock Salt is a chemical sedimentary rock that
forms from the evaporation of ocean or saline
lake waters. It is also known by the mineral
name "halite". It is rarely found at Earth's
surface, except in areas of very arid climate. It
is often mined for use in the chemical industry
or for use as a winter highway treatment.
ESRT Scheme for Identifying Sedimentary Rocks
Last but Not Least,
Metamorphic Rock
 Defined:
 form when any rock is changed by the effects
of heat, pressure, or chemical action.
 Two types of Metamorphism
 Regional or Contact
 Metamorphic rocks are typically
characterized as:
 unfoliated or foliated.
Metamorphic Rock

Metamorphic rocks form from either Igneous or Sedimentary rocks that are
effected by pressure and heat within the Earths surface.
Metamorphic Rock
 New types of Metamorphic rock are formed
depending on the amount of heat and
pressure present around the rock.
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Example: Sedimentary Rock – Shale
Regional Metamorphism
Contact Metamorphism
 When molten rock come into contact with
local rocks in a small area
Foliated Metamorphic Rocks
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Foliated Metamorphic Rock
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Definition:

Metamorphic rocks whose minerals
are squeezed together under high
pressure and arranged in wavy
layers or bands
 Examples:
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Gneiss is foliated metamorphic rock
that has a banded appearance and is
made up of granular mineral grains. It
typically contains abundant quartz or
feldspar minerals.
Schist is metamorphic rock with well developed
foliation. It often contains significant amounts of mica
which allow the rock to split into thin pieces
Joke of the day….
If it looks nice, it is probably Gneiss… If it looks like
Schist, it is probably Schist…. Get it???
 One more Example….
Slate is a fine-grained, foliated
metamorphic rock that is created by
the alteration of shale or mudstone
by low-grade regional
metamorphism
Nonfoliated Metamorphic Rocks

Definition:

Metamorphic rock that lacks
mineral grains that are banded.
Marble is a non-foliated metamorphic
rock that is produced from the
metamorphism of limestone
 Examples
Quartzite is a non-foliated
metamorphic rock that is
produced by the metamorphism
of sandstone.