Download rocks - Cobb Learning

Standard S6E5.c
Classify rocks by their
process of formation.
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What three characteristics
do scientists use to
identify rocks?
What are the three groups
into which geologists
classify rocks?
What is a rock’s texture?
What do the three major
groups of rock have in
common? How are they
different?
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Rocks are made of minerals and a mixture of
other materials
Some rocks are made of a single mineral
When studying a rock sample, geologists
observe the rock’s texture, origin and mineral
composition

A rock’s texture is the size, shape, and pattern of the
rock’s grains
Grain Size
a. fine-grained (small-basalt)
b. coarse-grained (large-granite)
Grain Shape
a. smooth and rounded (conglomerate)
b. jagged (breccia)
Grain Pattern
a. foliated (gneiss)
-mineral grains appear in parallel lines
b. nonfoliated (marble)
- minerals appear random
No Visible Grain
a. have no apparent grains (obsidian)
.
Origin how and where the rock was formed
1. igneous rock = forms from the melting, cooling and hardening of
molten rock
a. extrusive= formed above the surface (lava)
b. intrusive = formed below the surface (magma)
2. sedimentary rock = forms in layers from other
rocks, plants, and animals through a process of weathering,
erosion, deposition, compaction and cementation
a. clastic rock= formed from other rocks
b. organic rock= formed from things once alive
c. chemical rock= formed from saltwater solutions
3. metamorphic rock = formed when existing
rock is changed by heat, pressure, or chemical reactions
a. foliated rock= minerals arranged in bands
b. nonfoliated rock= grains arranged randomly
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By looking at a small sliver of a rock under a
microscope, geologists can observe the size and shape
of the crystals and identify the minerals the rock
contains
Also, geologists can do tests to identify the physical
properties of the minerals inside the rock.
Amount of Silicon in the Rock (mineral composition)
1. mafic= dark-colored rocks (poor in silica) (basalt)
2. felsic = ligt-colored rocks (rich in silica) (granite)
Compare – Rocks in each group make up the
Earth’s crust and are composed of minerals and
other materials
Contrast – Rocks are different in the way they are
formed
What terms describe a rock’s texture?
A. igneous rock, sedimentary rock, metamorphic
rock
B. grain size, grain shape, grain pattern
C. mantle, crust, core
D. clastic, organic, chemical
What three characteristics do scientists use to
identify a rock sample?
A. igneous, sedimentary, metamorphic
B. color, luster, hardness
C. inorganic, solid, crystalline struce
D. rock origin, texture, mineral composition
What are the three groups into which geologists
classify rocks?
A. grain size, grain shape, grain pattern
B. rock origin, mineral composition, texture
C. igneous, sedimentary, metamorphic
D. luster, color, hardness
Contrast: How are the three groups of rocks
different?
Compare: What do the three major groups of rock
have in common?
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What characteristics are
used to classify igneous
rocks?
What are the three (3)
ways that magma can
form?
What is the difference
between extrusive and
intrusive rocks? Give an
example of each.
Why are some igneous
rocks dark and others
light?
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Igneous rock forms when molten rock cools and hardens.
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Molten rock = liquid rock
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Igneous Rock forms by:
1. melting
2. cooling
3. hardening (solidifying)
Igneous rocks are classified by their origin.
Igneous rocks are classified by the texture of the grains
Igneous rocks are classified by the mineral composition of
the rock
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Three ways magma
can form:
 heat/rise in
temperature
 pressure released
 rock changes
composition
Three Ways Igneous Rocks Differ
1. Igneous rocks differ in origin:
- form either from lava, above the earth’s surface
- or from magma, below the earth’s surface.
2. They also differ in texture according to the size and shape of their
mineral grains. (course-grained or fine-grained)
3. Igneous rocks differ in mineral composition depending on how
much silica and other minerals are present. (felsic or mafic)
1. Origin – form above or below Earth’s surface
2. Texture – how fast they cool off (fine-grained or coarse-grained
3. Mineral Composition - what the rocks are made of
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Igneous rock form below and above Earth’s surface.
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Intrusive igneous rock – Intrusive rock forms when magma
hardens (below) Earth’s surface.
coarse-grained (large grains)
– below Earth’s surface (from magma)
– ex. granite (light colored rock = felsic)
–
Extrusive igneous rock – Extrusive rock forms from lava that has
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erupted (above) Earth’s surface.
fine-grained (small grains)
– on the Earth's surface (from lava)
– ex. basalt (dark colored rock = mafic)
–
Intrusive igneous rock –
Intrusive rock forms when
magma hardens (below)
Earth’s surface.
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
coarse-grained (large
grains)

below Earth’s surface
(from magma)

ex. granite (light colored
rock = felsic)
Extrusive igneous rock –
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Extrusive rock forms from lava
that has erupted (above) Earth’s
surface.

fine-grained (small
grains)

on the Earth's surface
(from lava)

ex. basalt (dark colored
rock = mafic)
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Mineral Composition –
Igneous rock rich in silicon/light-colored are
felsic rock.
Igneous rock poor in silicon/dark-colored are
mafic rock.
Texture – (grain size)
Fine-grained (small) = cools quickly = formed
above surface
Coarse-grained (large) = cools slowly = formed
below surface
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Most igneous rocks are hard, dense, and
durable.
Ancient Native Americans used obsidian for
making very sharp tools for cutting and
scraping.
Granite is used as a building material such as
decorative stonework, curbstones, and floors.
Basalt is crushed to make gravel.
The rough surface of pumice makes a good
abrasive for cleaning and polishing.
1. Which of the following are ways magma is
formed?
a.
b.
c.
d.
by compaction and cooling
by melting and cooling
by changes in composition
by weathering and erosion
2.
a.
b.
c.
d.
What kind of texture does igneous rock have
when magma cools slowly?
coarse-grained
large-grained
fine-grained
medium-grained
3. What kind of texture does igneous rock have
when magma cools rapidly?
a.
b.
c.
d.
coarse-grained
medium-grained
large-grained
fine-grained
4. What kind of rock is formed when magma
intrudes into other rock?
a.
b.
c.
d.
extrusive igneous rock
sedimentary rock
intrusive igneous rock
organic sedimentary rock
5. What kind of rock is formed from lava that cools
on Earth’s surface?
a. organic sedimentary rock
b. sedimentary rock
c. intrusive igneous rock
d. extrusive igneous rock
Uh, looks
like a
layered
cake to
me…
Stratification
Uluru, Australia
White Cliffs of Dover,
England
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Where does
sedimentary rock
form?
Describe the
formation of
sedimentary rock.
Describe the three
main categories of
sedimentary rock.

Describe four types
of sedimentary
features or
structures.
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Sedimentary rocks form
from particles deposited
by water and wind.
After sediment has
been deposited, the
processes of compaction
and cementation change
the sediment into
sedimentary rock.

Weathering- the breaking down of rock into
sediment by wind and moving water
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Erosion – movement of sediment away from its
source
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Deposition- process of which sediment settles out
of the water or wind carrying It into layers.
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Compaction- the process that presses sediment or
layers together.
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Cementation- the process in which minerals
crystallize and glue particles of sediment together.
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Geologists classify
sedimentary rocks
according to the type
of sediments that
make up the rock.
There are three major
groups of sedimentary
rocks: clastic rocks,
organic rocks, and
chemical rocks.
A clastic rock forms
when sediments are
compacted and
cemented together.
 (rocks made from
other rocks)
 Examples of clastic
rocks:
 Shale
 Sandstone
 Conglomerate
 Breccia
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Shale forms from
tiny particles of clay.
Shale feels smooth,
and splits easily into
flat pieces
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Sandstone forms
from the sand on
beaches, on the
ocean floor, in
riverbeds, and in
sand dunes.
Sandstone is formed
when small particles
of sand are pressed
and cemented
together.
.
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Conglomerate is a
rock made up of
large particles with
rounded edges.
Breccia is a rock
made up of large
fragments with
sharp edges.
Organic rock forms from
the remains of plants and
animals that once lived in
the ocean.
The term “organic” refers
to substances that were
once part of living things.
Three important organic
rocks:
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Coal
Limestone
Chalk
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Coal forms from the
remains of swamp plants
buried in water.
Over millions of years,
they slowly change into
coal.
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The hard shell of
living things produces
limestone.
Chalk forms from
sediments made of
skeletons of
microscopic living
things found in the
ocean.
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Chemical rock forms
from solutions of
dissolved minerals and
water.
Chemical rocks can also
form when mineral
deposits are left from
evaporating seas or lakes.
Examples:
 rock salt (halite)
 Gypsum
Stalactites – sharp, icicle shapes that grow
downward from the ceiling
Stalagmites – cone-shape features that grow
from the floor upwards.
Rock Salt (Halite) – forms
when large bodies of salt
water evaporate
Gypsum - found in
evaporated sedimentary
deposits
Sedimentary Rock
Features:
-Stratification
-mud cracks
- ripple marks
- rain-drop impressions
Grand Canyon,
Arizona
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The most important
feature of
sedimentary rock is
stratification.
Strata –
- layers of rock
Stratification – the
process in which
sedimentary rocks
are arranged in
layers
Location?
Ripple marks are made by the motion of wind
and water waves on lakes, oceans, rivers, and
sand dunes.
Mud cracks
form when
fine-grained
sediments at
the bottom
of a shallow
body of
water are
exposed to
air and dry
out.
Rain-drop
impression
s can be
preserved
in finegrained
sediments,
as small
pits with
raised
rims.
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Sandstone and limestone are used as building materials.
The White House in Washington, D.C. is built of sandstone.
Limestone is also used to make cement.
Breccia is used as architectural stones for interior building
veneers, tiles, window sills and other decorative applications.
Coal is used for electricity, steam, heat and coke production.
Conglomerate has very few commercial uses. Its inability to break
cleanly makes and unreliable physical strength a poor candidate
for decorative use.
Shale is used for oil and natural gas.
Rock salt is also known as the mineral “halite”. It is often used in
the chemical industry or for use as a winter highway treatment.
Some halite is processed for use as a seasoning for food.
Gypsum uses include: manufacture of wallboard, cement, plaster of
Paris, soil conditioning.
Which process forms sediment?
a.
b.
c.
d.
weathering
cementation
compaction
deposition
What are strata?
a.
b.
c.
d.
mineral fragments
minerals crystallized out of solution
layers in sedimentary rock
fossils in sedimentary rock
What kind of sedimentary rock is
made of fragments of rocks
cemented together by a mineral?
a.
b.
c.
d.
organic
stratified
chemical
clastic
What kind of sedimentary rock is
made from solutions of dissolved
minerals in water?
a.
b.
c.
d.
organic
chemical
stratified
clastic
What kind of sedimentary rock is
made from fossils?
a.
b.
c.
d.
organic
stratified
chemical
clastic
What is the process called in which
sedimentary rocks are arranged in
layers?
a.
b.
c.
d.
erosion
extrusion
weathering
stratification
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How are metamorphic rocks
formed?
Describe two ways a rock can
undergo metamorphism.
Describe the difference
between foliated and
nonfoliated metamorphic
rock.
What are some examples of
metamorphic rock and how
are the examples used?
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Metamorphic rock is formed when existing rock is
changed by heat, pressure, or chemical reactions.
Heat and pressure deep beneath Earth’s surface can
change any rock into metamorphic rock.
Metamorphic rocks are classified by the
arrangement of their mineral grains.
Metamorphic rocks are rocks in which the
structure, texture, or composition has changed.
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The two types of metamorphic rocks are
called foliated rock and non-foliated rock.
Foliated rock is when the grains are parallel
or arranged in planes or bands.
Non-foliated rock refers to where the grains
are arranged randomly.
Foliated Rock
Mineral grains are
arranged in planes
or bands
The effects of
metamorphism depend
on the heat and
pressure applied to the
rock.
The picture on the right
shows what happens to
shale (sedimentary)
when it is exposed to
more and more heat and
pressure
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

Slate
(from shale)
Gneiss
(from granite)
mineral grains are not arranged in planes or bands
Quartzite
(from quartz)
Marble
(from limestone)
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Metamorphism occurs
when temperature and
pressure in the earth’s
crust change.
Minerals present when
the rock formed, may
not be stable in the new
environment
The original minerals
will change into
minerals that are more
stable in the new
environment.
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Scientists can understand
a metamorphic rock’s
history by observing the
minerals the rock
contains.
For example, a
metamorphic rock that
contains garnet, formed
at a greater depth, greater
heat and pressure than a
rock that contains only
chlorite.
The texture or mineral composition of a rock can
change if the surroundings change
If the temperature or pressure of the
environment is different than the one in which
the rock formed, the rock will undergo
metamorphism
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Meta = change
Morph = shape
Origins of
Metamorphic Rock
This metamorphic rock
is an example of how
mineral grains were
aligned into distinct
bands when the rock
underwent
metamorphism.
Meta = changed
Morph = shape
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Contact Metamorphism – happens when rock is heated by
nearby magma.
Minerals in surrounding rock changes into other minerals
because of increased temperature.
Occurs near igneous intrusions, such as plate movement.
Occurs over small areas
Regional Metamorphism – happens when pressure builds
up around rock deep beneath other rock formations or when
pieces of the Earth's crust collide with each other
Increased temperature and pressure causing rock to become
deformed and chemically changed.
Occurs over large areas, such as mountain ranges.
Contact Metamorphism occurs over small areas, such as
next to bodies of magma.
Regional Metamorphism occurs over large areas, such
as beneath mountain ranges
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Metamorphic rock has features that tell you abou
its history.
In metamorphic rocks, these features are caused
by deformation.
Deformation is a change in the shape of a rock
caused by a force placed on it.
These forces may cause a rock to be squeezed or
stretched.
Folds or bends in metamorphic rock are structure
that indicate that a rock has been deformed.
Metamorphic Rock Structures
These large folds occur in metamorphased sedimentary
rock along Saglet Fjord in Labrador, Canada
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Marble and slate are the two most useful
metamorphic rocks and come in a variety of colors.
Marble can be cut into thin slabs and easily
polished (Taj Mahal).
Slate , because it is foliated, splits easily into flat
pieces and is used for flooring, roofing, outdoor
walkways, or chalkboards.
Gneiss is very appealing to the eye. It can be used
for buildings, roads and curbs.
Schist is found in preparations for ezcema, and in
medicines to cure boils in humans and animals.
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There are 3 major rock groups: igneous rocks
sedimentary rocks and metamorphic rocks.
Igneous rocks form when molten rock cools and
hardens from magma or lava.
Sedimentary rocks form from particles deposited,
pressed, and cemented together by water and
wind.
Metamorphic rocks form from heat and pressure,
or a chemical change.
Forces inside Earth and at the surface produce a
rock cycle that builds, destroys, and changes the
rocks in the crust.
1. How does metamorphic rock form?
a. by intense heat and pressure
b. erosion, deposition, compaction, cementation
c. melting into lava or magma, then cooling into a
new rock
d. by pressing together and then cementation
2. Molten rock beneath Earth’s surface is called
a.
b.
c.
d.
lava.
magma.
sedimentary rock.
igneous rock.
3. If you wanted to duplicate conditions in a
laboratory that produced metamorphic rock from
sedimentary rock, what would you need to do?
a. apply pressure to the rock
b. apply high temperature to the rock
c. apply high pressure and high temperature to
rock
d. let the rock stand under water for a long time
the
4. Which of the following is a metamorphic rock?
a.
b.
c.
d.
granite
sandstone
limestone
marble
5. Metamorphic rocks can be formed from
a. igneous rocks.
b. sedimentary rocks.
c. metamorphic rocks.
d. all rock groups.
6. The rock formed when granite changes to a
metamorphic rock is
a. marble.
b. basalt.
c. gneiss.
d. pumice.
7. Metamorphic rocks that have their grains
arranged in parallel bands or layered are said
to be
a. jagged grained.
b. foliated.
c. nonfoliated.
d. coarse grained.
8. The heat that changes a rock into metamorphic
rock comes from
a. friction of plate movement.
b. the sun.
c. the heat of the mantle.
d. chemical rocks in the crust.
9. Which rock’s name comes from the Greek
words for “changed” and “shape”?
a. metamorphic
b. sedimentary
c. fossiliferous limestone
d. igneous
10. What are the two ways a rock can undergo
metamorphism?
a. weathering and erosion
b. compaction and cementation
c. Contact and Regional
d. cooling and hardening
11. Geologist classify metamorphic rock according
to
a. the exterior color of the rock.
b. the overall shape of the rock.
c. the arrangement of the grains that make up the
rock.
d. the degree of hardness of the rock.
EQ: What is the rock cycle?
•
What materials are
rocks made of?
•
Describe four
processes that
change rock from
one type to another.
•
What are the three
main classes of rock?
•
Describe two
characteristics of
rock that are used to
help classify it?
What materials
are rocks made
of?
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Rock is describe as a naturally
occurring solid mixture of one or
more minerals and organic
matter.
Rocks are made of mixtures of
minerals and other materials,
although some rocks may
contain only a single mineral.
When studying a rock sample,
geologists observe the rock’s
origin, color and texture and
determine its mineral
composition.
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Texture is described with terms based on grain
size, grain shape, and grain pattern.
Most rocks are made up of tiny particles of
minerals or other rocks, which are called grains.
A rock’s grains give it its texture.
There are three major groups of rocks: igneous
rock, sedimentary rock, and metamorphic rock.
These terms refer to how the rocks in each
group were formed (origin).
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The rock cycle is a series of
processes in which a rock
forms, changes from one type
to another, is destroyed, and
forms again by geological
processes.
Rocks have been used by
humans to make tools and
weapons and to construct
buildings.
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Certain geological processes make and destroy
rock.
These processes shape the features of the Earth.
These processes also influence the type of rock
that is found in a certain area of Earth’s
surface.
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Weathering is the process by which water,
wind, ice, and heat break down rock.
Erosion is the process by which sediment is
removed from its source.
Deposition is the process by which sediment
moved by erosion is laid down.
Uplift is the process by which rock within the
Earth moves to Earth’s surface.
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Igneous rock is formed when magma or lava is
cooled and hardens and solidifies.
Sedimentary rock is formed by the process of
weathering, erosion, deposition and compaction
and cementation.
Metamorphic rock is formed by heat, pressure
or chemical change deep beneath Earth’s surface.
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Scientists classify rocks in detail by using two
important criteria – composition and texture.
Composition is the chemical makeup of a
rock; describes either the minerals or other
materials in the rock.
Texture is the quality of a rock based on the
sizes, shapes, and positions of the rocks
grains.
1.
a.
b.
c.
d.
Which of the following rocks is not normally
used as a construction material?
marble
halite
limestone
granite
2. The process in which wind, water, ice, and heat
break down rock is called
a.
b.
c.
d.
uplift.
intrusion.
recystallization.
weathering.
3. What forms when rock partially or completely
melts?
a.
b.
c.
d.
limestone
reefs
ripple marks
magma
4. Scientists classify rocks
a.
b.
c.
d.
by composition and texture.
by volume.
by mass.
by color and size.
Solid mixture of one or more minerals and
organic matter:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
Process by which new rock forms from old
rock:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
Process by which sediment is removed from its
source:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
Process by which sediment is dropped and comes
to rest:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
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There are 3 major rock groups: igneous rocks
sedimentary rocks and metamorphic rocks.
Igneous rocks form when molten rock cools and
hardens from magma or lava.
Sedimentary rocks form from particles deposited,
pressed, and cemented together by water and wind.
Metamorphic rocks form from heat and pressure, or
a chemical reaction.
Forces inside Earth and at the surface produce a rock
cycle that builds, destroys, and changes the rocks in
the crust.
Size, shape, and position of grains that make up a
rock:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
10. Which type of rock is MOST LIKELY to form
layers?
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


A.
B.
C.
D.
Sedimentary
Igneous
Metamorphic
magma
11. The _________ of a rock is determined by the
sizes, shapes, and positions of the minerals the
rock contains.
12. ________ metamorphic rock contains minerals
that are arranged in plains or bands.
13. The most characteristic property of
sedimentary rock is __________.
14. Sedimentary rock is classified into all of the
following main categories except _________.
a. clastic sedimentary rock
b. chemical sedimentary rock
c. nonfoliated sedimentary rock
d. organic sedimentary rock
15. An igneous rock that cools very slowly has a
__________ texture.
a. foliated
b. fine-grained
c. nonfoliated
d. coarse-grained
The chemical makeup of a rock:
a. composition
b. rock
c. erosion
d. texture
e. rock cycle
f. deposition
16. Igneous rocks form when
a. minerals crystallize from a solution.
b. sand grains are cemented together.
c. magma cools and solidifies.
d. mineral grains in a rock recrystallize.
17. A __________ is a common structure found in
metamorphic rock.
a. ripple mark
b. fold
c. sill
d. layer
18. The process in which sediment is removed
from its source and transported is called
____________.
a. deposition.
b. erosion.
c. weathering.
d. uplift.
19. Mafic rocks are
a. light-colored rocks rich in calcium, iron, and
magnesium.
b. dark-colored rocks rich in aluminum,
potassium, silica, and sodium.
c. light-colored rocks rich in aluminum,
potassium, silica, and sodium.
d. dark-colored rocks rich in calcium, iron, and
magnesium.