What are the three types of rocks
that form the rock cycle?
•Igneous
•Metamorphic
•Sedimentary
lithification
• transformation of sediments into rock
through compaction and cementation
Compaction
 the
process in which pressure
squeezed air and water out and
pushes fragments together
 pressure
comes from rock layers
Cementation
 the
process in which water and
minerals combine to from cement
that holds sediment together.
Three Types of Sedimentary
Rocks
• Clastic Sedimentary Rocks
• Evaporites Sedimentary Rocks
• Organic Sedimentary Rocks
organic - once living
Clastic Sedimentary Rocks
• Formed by sediments carried by
wind, water, or ice and deposited
elsewhere
Clastic Sedimentary Rocks
• Conglomerate – cemented rounded
gravel (older, weathered rock)
• Breccia – cemented sharp cornered
pieces (newly broken rock)
• Sandstone – cemented sand sized
grains that are mostly quartz
Chemical Sedimentary Rocks
• Formed from minerals that
were once dissolved in water
Evaporites
• Formed when a
change in
temperature
caused water to
be evaporated
• Examples:
Gypsum and
Halite
GYPSUM
HALITE
Organic Sedimentary Rock
• formed from the remains of living
things
FOSSILIFOROUS
LIMESTONE
Coal
• Formed from the remains of
ancient decayed plants
BITUMINOUS COAL
COAL POWER PLANT
Limestone
• the shells of calcite rich marine
organisms like coral, clams, and
oysters
LIMESTONE
LIMESTONE WALL
Metamorphic Rocks
• Are rocks formed from an increase in
pressure and temperature deep within the
lithosphere.
How are metamorphic
rocks classified?
Metamorphic rocks are
classified by how they
are formed.
Three Types of
Metamorphic Rocks
• Contact Metamorphism
– occurs when molten rocks, such as those in
an igneous intrusion, come in contact with
solid rock
Regional Metamorphism
• are produced when high temperature and
pressure affect large regions of Earth’s
crust.
• the grade of regional metamorphism
reflects the intensity of temperature and
pressure
• classified as low grade, intermediate
grade, and high grade.
Hydrothermal Metamorphism
• occurs when very hot water reacts with
rock and alters its chemistry and
mineralogy
• hydrothermal fluids can dissolve some
minerals, break down others, and deposit
new minerals
• is common around igneous intrusions and
near active volcanoes
Nonfoliated
• composed mainly of minerals that form with
blocky crystal shapes.
– Quartzite and marble are two common examples
of nonfoliated rocks.
Foliated
• metamorphic rocks are characterized by bands
of minerals
• high pressure during metamorphism causes
minerals with flat or needlelike crystals to form
with their long axes perpendicular to the
pressure
Igneous Rocks
• Igneous rocks are rocks that are formed
from the crystallization of magma.
Heat and
melting
Magma
Cooling and
crystallization
Igneous
Rocks
Igneous Rocks Are Separated into
Two Main Categories
EXTRUSIVE
INTRUSIVE
Extrusive Igneous Rocks
• Extrusive igneous
rocks are fine-grained
igneous rocks that cool
quickly on Earth’s
surface.
• Obsidian is an example
of an extrusive igneous
rock.
Intrusive Igneous Rocks
• Intrusive igneous rocks are coarsegrained igneous rocks that cool slowly
beneath
Earth’s surface.
• Granite is the most common intrusive
igneous rock.
Igneous Rocks are Categorized by
Texture
• Texture is determined by cooling time
– Glassy Cooled very fast
– Fine Grained Cooled fast
– Course Grained Cooled slowly
– Very Course Grained Cooled very slowly
Porphyritic Texture
– A rock that has a porphyritic texture is
characterized by large, well-formed crystals
surrounded by finer-grained crystals of the same
mineral or different minerals.
How are igneous rocks
grouped?
Igneous rocks are
grouped by their
mineral composition.
Felsic si
–contains more silicon
–lighter in color
–Granite
–Makes up continental crust
Mafic
–contains less silicon
–darker in color
–rich in iron and magnesium
–Makes up oceanic crust
Intermediate
–have characteristics of both
felsic and mafic
Ultramafic
–contains very little silicon
–very dark in color
–very rich in iron and magnesium
–Earth’s mantle is ultramafic