The Rock Cycle
Earth Science
Ms. Kurtzweil
Most rocks are made of minerals
► Jigsaw
puzzle
 Each piece is an important part of the
final picture
 Minerals combine to form most rocks
► Rocks
are like words
 Letters combine to make words
 Minerals combine to make rocks
► Rock:
a naturally formed solid that is usually
made up of one or more types of minerals
Our world is built of rocks
► Used
for building
houses and
skyscrapers
► Sources of metals,
such as iron,
aluminum, and copper
► Carved into statues
and other works of art
and culture
► Basis for pavement for
roads and highways
Like a Rock
► Solid,
dependable, unchanging….
► Really?
► Rocks DO change, over huge
time spans
 Thousands to millions of years
► Rock
Cycle: the set of natural
processes that form, change,
break down, and re-form rocks
The Rock Cycle
The Rock Cycle
► Repeating
events
► Changes do not occur in any particular order
► A rock at any point in the cycle can change in
2 or 3 different ways
► Has no beginning or end; goes on continually
Rocks are classified by how they are
formed
► Igneous
 Molten rock cools and
becomes solid
 Within Earth, or on
Earth’s surface
 Can reach surface over
time by weathering or
uplifting
 Will be weathered when
they reach the surface
Rocks are classified by how they are
formed
►
Sedimentary
 Forms when pieces of older
rocks, plants, and other loose
material get pressed or
cemented together.
 Loose material is carried, settles
forming layers
 Pressure compacts sediments
together
 New minerals cement
sediments together
 Water evaporates, leaving
behind dissolved minerals
Rocks are classified by how they are
formed
► Metamorphic
 Heat or pressure causes
older rocks to change
into new types of rocks
 Deeper into crust,
temp. and pressure
greater
 Can be raised to the
surface and weathered
over time
Rocks in the Crust
►
Rock types are not
evenly distributed
 Surface of the crust:
► 75%
sedimentary
► 25% igneous and
metamorphic
 Entire crust
► 95%
igneous and
metamorphic
► 5% sedimentary
Rocks in the Crust
► Distribution
is a reflection of the rock cycle
 Why would more sedimentary rocks be found at the
surface?
 Why are most igneous and metamorphic rocks found
deeper within the Earth?