7th Grade-Ch. 5 Sec. 5 Metamorphic Rocks
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Transcript of 7th Grade-Ch. 5 Sec. 5 Metamorphic Rocks
Ch. 5Ch. 5Sec. Sec. 55Read Read pgs. pgs. 160-160-162162
The word "metamorphic"
comes from Greek and
means “to change
form".
Collisions between Earth’s plates push rock down toward the mantle.
Earth’s plates
Heat & pressureHeat & pressure deep beneath Earth’s surface
can changechange any rock into metamorphic rock.
form from:igneous
sedimentary other metamorphic
rock
classified by arrangement of grains1. foliated2. nonfoliated
grains arranged in parallel layers or bands- heat & pressure flatten crystals
foliated
Examples:
foliated- walking single file
grains arranged randomlynonfoliated
Examples:
Figure out foliation! Try this experiment to figure out how minerals
become oriented when a rock is under pressure.
1. Add mica flakes to a piece of play dough. The dough will represent a rock undergoing metamorphism.
2. Knead the dough until the mica flakes are well-incorporated roll your dough into a ball.
3. Break the ball of dough in half. The flakes will be oriented in all different directions just as they would be in an unmetamorphised rock.
4. Take one half of the ball and flatten it with the palm of your hand. The pressure that you are applying to the dough is like the pressure placed on our rocky Earth by the forces of plate tectonics.
5. Break the flattened dough in half and look at what has happened to the mica flakes!
It’s gneiss not to be taken for granite anymore!
sandstone quartzite
• The weakly cemented quartz particles in the sandstone recrystallize to form quartzite.
limestone marble
Video Clip-Metamorphic Rock
Uses of metamorphic
rocks:
marble - used to build buildings & statues
•fine, even grain
•can be cut into thin slabs or carved into many shapes
•easy to polish
slate-•used for flooring, chalkboards
•foliated- splits easily into flat surfaces
What does metamorphic
mean?
The word "metamorphi
c" comes from Greek and means “to change
form".
Where and under what conditions
are metamorphic rocks formed?
Heat & pressureHeat & pressure deep beneath Earth’s surface
can changechange any rock into metamorphic rock.
What characteristic of
metamorphic rocks do geologist
use to classify them?
Geologists classify metamorphic rocks by the arrangement of their grains.1. foliated2. nonfoliated
How does a foliated
metamorphic rock form?
A foliated metamorphic rock is formed when heat and pressure flatten the
crystals in the rock.
Which of these rocks is foliated? How can you tell?
Quartzite
The grains in a foliated rock are arranged in parallel layers or bands.
foliated- walking single file
What is the main use of metamorphic rocks?
• The main use of metamorphic rocks is for building and sculpture.
Which might be more useful for carving chess pieces-marble or
slate? Explain your answer.• Marble would be more
useful for carving chess pieces because marble can be carved into many shapes and be easily polished.
Activity-A Sequined Rock1. Make three balls of clay about 3 cm in diameter. Gently mix
about 25 sequins into one ball.2. Use a 30-cm piece of string to cut the ball in half. How are
the sequins arranged?3. Roll the clay with the sequins back into a ball. Stack the three
balls with the sequin ball in the middle. Set these on a block of wood. With another block of wood, press slowly down until the stack is about 3 cm high.
4. Use the string to cut the stack in half. How are the sequins arranged?
5. Making Models What do the sequins in your model rock represent? Is this rock foliated or nonfoliated?