Unit D: Cycles in Earth and in space
Chapter 2: Rocks and the rock cycle
Minerals and rocks
A mineral is a solid nonliving substance
that occurs naturally in rocks or in the ground.
A rock: is a naturally formed solid that is made up of one or more types of
minerals.
Types of rocks:
1-Ignoeus rocks:
The rock that forms when melted rock hardens is called igneous rock.
This rock is the result when melted rock within Earth, called magma, is pushed up
from the mantle to the crust, which is cooler. The cooler temperatures cause
the magma to harden into rock.
-Igneous rock will be either intrusive or extrusive depending on where it cools.
Intrusive igneous rock cools deep within Earth’s crust.
Extrusive igneous rock cools on Earth’s surface.
Sedimentary Rock
Sedimentary rock forms when layers of sediment—bits of rock carved by
wind, water, or ice—settle over time and bind together. Sedimentary rock is
divided into two main groups—clastic and chemical.
1-Clastic sedimentary rocks:
The word clastic comes from a Greek word meaning “broken.” Clastic rock
forms from rock that is broken into smaller pieces.
This is the result of natural processes such as wind and rain weathering
rock, forming sediment.
Next, wind and water move the sediment. Layers of sediment build up over
a long period of time. Water deposits minerals, such as calcite, in the spaces
between the particles. These minerals glue the layers together.
Finally, the layers are pressed and cemented together to form rock.
Chemical sedimentary rock forms when chemicals in water come out of
the water and form solids. This happens when water that contains a large
amount of a solid compound evaporates and leaves the solid behind.
-Limestone, one very common chemical sedimentary rock, forms in a
different way. When animal shells or skeletons pile up at the bottom of an
ocean or lake, they can become cemented together and form rock.
Sometimes you see shells in the rock, but not always.
Lime stone usually contains fossils.
Metamorphic Rock
Metamorphic rock forms when igneous, sedimentary, or metamorphic rock
is changed by pressure, high temperature, very hot water, or a
combination of these factors.
High temperature is the most important cause of metamorphism, the
process by which metamorphic rock is formed.
Uses of Rock
1-Igneous rock is used in everything
from construction materials to jewelry.
Granite is an igneous rock that builders
use because it lasts a long time.
Obsidian was once used for blades in tools because
of the sharp edges it has when broken.
Obsidian’s shiny black surface also
makes it a favorite of jewelry makers.
Pumice is an igneous rock that can be ground
into powder and used in cleaning products.
2-sedimentary rock has a wide variety of uses.
Shale and mudstone are used in construction.
-Energy resources such as petroleum and natural gas are found in
sedimentary rock.
Rock salt or halite is used to season and to preserve food.
Metamorphic rock is a popular building material.
Marble is prized for its unique look
and is used in many public buildings
and artistic sculptures.
Talc is a mineral that comes from schist.
Talc is a powder used in cosmetics.
The Rock Cycle
The processes that change rock from one kind to another are called
the rock cycle.
A.Write the letter of the best choice.
1. What type of rock is formed when a volcano explodes? S3E1b
A. igneous
B. metamorphic
C. sandstone
D. sedimentary Concepts
2. What does this picture show? S3E1d
A. how sediments build up
B. the rock cycle
C. types of soil
D. igneous rock
3-Gneiss is a rock that changed from granite by heat and pressure.
Which type of rock is gneiss?
a-igneous
b-marble
c-metamorphic
d-sedimentary
4- Which of the following processes can change a metamorphic rock into
sedimentary rock?
a-adding pressure
b-increasing temperature
c-melting
d-weathering
5-Rock changed by heat and pressure is known as
a-Igneous
b-Marble
c-Metamorphic
d-Sedimentary
6-Rocks continually change into other types of rocks into the
a-adding pressure
b-increasing temperature
c-melting
d-rock cycle
7-pieces of sediment settle out of water or wind during..................
a- pressure
b- weathering
c-deposition
d-erosion
8-Which of the following is a good definition of the word rock?
a- A rock is any nonliving solid found in nature.
b- A rock is anything found in the ground
c-a rock is a hard object
d-a rock is a mineral mixture
9-Which effect do high temperature and pressure have on igneous rock?
A. They turn igneous rock into soil.
B. They have no effect.
C. They change igneous rock to sedimentary rock.
D. They change igneous rock to metamorphic rock.
10-Which of the following is NOT true of the rock cycle?
A. Soil never becomes rock.
B. Igneous rock can become sedimentary rock.
C. Any rock can become a different kind of rock.
D. Metamorphic rock forms by exposure to heat and pressure.
B.Match the clue on the left with the term on the right. Write the
letter in the blank.
1-rock that is changed from one form to another
by high heat and great pressure
A. igneous rock
2-rock formed when melted rock cools and hardens
B. sedimentary rock
3-rock formed by compacted and cemented particles
C. metamorphic rock
C.Match the clue on the left to the term on the right. Write the letter
in the blank.
rock changed by pressure and very high heat
A. igneous
rock formed by layers of sediment that bind together
B. metamorphic
magma that has reached Earth’s surface
C. lava
melted rock that has crystallized
D. sedimentary
D.Complete the graphic organizer below.
E.Complete the graphic organizer below.
F.Answer the following:
1-One type of rock can become another type of rock.
Explain how this is possible.
.
.
.
2-It is common to find fossils in sedimentary rocks. One way fossils form is
that when ocean animals die, their shells, teeth, and bones drop to the ocean
floor. Those pieces become part of the sediment layer. It is not common to
find fossils in igneous rock. Why?
.
.
.
3-Suppose a geologist shows you two different rocks. She tells you that one
of the rocks is sedimentary and the other is igneous. How can you identify
each kind of rock?
.
.
.
4-John says that a metamorphic rock can form from a sedimentary rock.
Clare says that a metamorphic rock can form from an igneous rock.
Who is correct? Explain.
.
.
.
RS
G.Put the following changes to rocks in the correct sequence.
Number the events 1 to 3.
Sediment is cemented into a sedimentary rock.
Small pieces are weathered from a metamorphic rock.
Sediment is deposited in a different place.