2. What is a Rock?
• Naturally-occurring mixtures
of minerals, mineraloids, glass
or organic matter.
3. What is a Rock?
• Rocks are divided into 3
groups based on how they
were formed:
• IGNEOUS
• SEDIMENTARY
• METAMORPHIC
4. What is the difference
between a rock and a
mineral?
• Rocks are made up of ONE or
MORE minerals.
5. What is the process through
which rocks change?
• The Rock Cycle—
earth materials change back and forth
among the different types of rocks
6. • Once a rock is formed, does it stay
the same rock forever? NO!
• Rocks are continually changed by
many processes, such as weathering,
erosion, compaction, cementation,
melting, and cooling
• Rocks can change to and from the
three different types
9. There is no set path a rock takes to
become another kind of rock
10. Now you complete a
Rock Cycle diagram.
Identify the Rock Types
formed by writing the
name ins the ovals.
IGNEOUS
Weathering, Erosion,
Compaction, Recrystallization
Cementation
Melting,
Solidification Melting,
Solidification
Recrystallization
SEDIMENTARY METAMORPH
Weathering, Erosion,
IC
Compaction,
Cementation
11. How are rocks redistributed?
• The core, mantle, & crust are one giant
rock recycling machine !
13. Questions--
1. What do igneous rocks form from?
2. What kind of rock are fossils found?
3. What are metamorphic rocks formed
by?
Remember: The rock cycle is a
continuous process that occurs over
millions of years. It makes new
rock, destroys old rock, and
recycles the ingredients of the
Earth's crust over and over again!
14. • “Ignis” = Latin for “fire”
• Formed from the cooling of either
magma or lava
• The most abundant type of rock
• Classified according to their origin and
composition
15. ORIGIN— Where rocks are formed
• Below ground = from magma (intrusive
igneous rock)
• Usually have LARGE crystal grains (they
cooled slowly)
16. Some have large & small crystals
(called porphyritic)
Above ground = from lava (extrusive
igneous rock)
Usually have SMALL or NO crystals
(they cooled too quickly)
17. COMPOSITION— What kind of
substances the rocks are made of
• Basaltic Igneous Rocks —made from lava/magma that is
low in silica, rich in iron and magnesium. Rocks are
dark-colored.
• Granitic Igneous Rocks—made from magma/lava high in
silica and oxygen. Rocks are light-colored.
• Andesitic Igneous Rocks—have a composition between
basaltic and granitic.
19. • Formed from sediments
(rock fragments, mineral
grains, animal & plant
remains) that are pressed
or cemented together or
when sediments precipitate
out of a solution.
20. • These sediments are moved by wind, water,
ice or gravity.
• Sedimentary rocks represent 7% of the
Earth’s crust, but they cover 70% of the
Earth’s surface.
• Sedimentary rocks are
fossil-carrying rocks.
21. What turns sediments into solid rock?
• Water or wind breaks down and
deposits sediment (erosion &
deposition)
22. • The heavy sediments press down on
the layers beneath (compaction)
23. • Dissolved minerals flow between the
particles and cement them together
(cementation)
24. How can sedimentary layers help us
understand the age of fossils?
• As sedimentary rocks are deposited, they
form horizontal layers.
• Scientists know that the layers on top (and
the fossils in the top layer) are YOUNGER
than the fossils in lower layers.
http://youtu.be/9Df4CtlZ0AQ
26. 3 Types of Sedimentary
Rocks:
• Clastic (also called Detrial)—made of
broken pieces of other rocks.
• Organic—remains of plants and animals
are deposited in thick layers
– Examples: Fossil rich limestone is made
from the shells of ocean animals; used to
make chalk
• Chemical—minerals dissolved in lakes,
seas, or underground water
27. Examples
• Limestone
made when
calcite
mineral
precipitates
from sea
water
• Rock Salt—
made from
evaporation
of sea
waters
28. • Rocks that have changed due to
intense temperature and pressure
• “Meta” means “change” and morphosis
means “form” in Greek
• Igneous, sedimentary and other
metamorphic rocks can change to
become metamorphic rocks
29. What occurs in the Earth to
change these rocks?
• Pressure from overlying rock layers
• High heat, but not enough to melt the rock
• Rocks may be flattened or bent or atoms may
be exchanged to form new minerals.
30. • *You can think of metamorphic rocks
as a squished peanut butter & jelly
sandwich in your lunch.
31. How are metamorphic rocks
classified?
1. Foliated—mineral grains are
flattened and line up in parallel
bands
– Example: gneiss formed from
rearrangement of minerals in granite into
bands
33. Where do metamorphic rocks
usually form?
• Where magma intrudes relatively cool rock
• Near colliding plates (near mountain ranges)
• Places that are covered miles thick with other
rock causing pressure
• When hot water intrudes rock
• Where a meteorite strikes Earth (rare)
• Where lightning bolts strike rocks (rare)
36. Final Vocabulary Words
• Uplift: The rising of regions of the Earth’s
crust to higher elevations.
• Strata: layers of Rock.
• Fossils: The trace or remains of an
organism that lived long ago, commonly
preserved in sedimentary rocks.
• Magma: Molten material on the inside of
Earth’s crust.
• Lava: molten material on Earth’s surface.
37. Vocabulary Review
• Foliated: A metamorphic rock in which
the mineral grains are arranged in planes
or bands.
• NonFoliated: a metamorphic rock in
which the mineral grains are NOT
arranged in planes or bands.
• Index Fossils: a fossil found in the rock
layers of only one geological age and that
is used to establish the age of the rock
layers.
38. Vocabulary Review
• Stratification: The process in which
sedimentary rocks are arranged in layers.
• Coal: a fossil fuel that forms
underground from partially decomposed
plant material.
39. Vocabulary Review
• Rock Cycle: the series of processes in
which a rock forms, changes from one type
to another, is destroyed, and forms again
by geological processes.
• Rock: a naturally occurring solid mixture
of one or more minerals or organic matter.
• Erosion: the process by which sediment
is moved from one location to another.
• Weathering: process by which rock is
broken down into smaller pieces.
40. Vocabulary Review
• Sediment: small solid particles of rock
and inorganic/organic material.
• Sedimentary Rock: a type of rock
formed when particles from other rocks or
the remains of organisms are compacted
and cemented together.
• Deposition: the process by which
sediment is “dropped” and comes to rest.
• Cementation: process by which
dissolved minerals crystallize and glue
particles of sediment together.
41. Vocabulary Review
• Compaction: the process by which
sediments are pressed together.
• Igneous Rock: a type of rock that forms
from the cooling of magma or lava.
• Metamorphic Rock: a type of rock
formed from existing rock changed by
heat, pressure, or chemical reactions.