Earth Science Ch' 13B: The Rock Cycle

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Earth Science Ch. 13BThe Rock Cycle
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Background Knowledge

• The following information is from earlier in the
  chapter and will help you better understand the
  rest of the chapter.

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Test For Identifying A Mineral

• A Mineral Must Be
• Naturally Occurring on the Earth
• Inorganic
• A Solid
• A Definite Chemical Composition
• A Crystalline Structure
• There Are About 2500 Known Minerals

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Formation and Composition of Minerals

• Minerals Form From Cooling Solutions.
• Minerals can form in a variety of ways, usually,
  though, from cooling/evaporating water or cooling
  magma/lava.
• The slower the water/magma/lava cools or
  evaporates, the LARGER the crystals that will
  form.

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Identifying Minerals

• Minerals have certain physical properties that
  can be used to identify them.
• These include
• Color
• Luster
• Hardness
• Streak
• Density
• Crystal Shape
• Cleavage and Fracture
• Other Special Properties

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Uses of Minerals

• Today, many of the Earths minerals are used to
  meet the everyday needs of people.
• Some common uses for minerals

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Ores

• The term ore is an economic term that describes
  rocks that contain minerals in useable amounts.
• Ores come in two varieties Metals and
  Non-Metals.
• Most ores are rocks that contain two or more
  minerals.

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Gemstones

• Gemstones are divided into 2 categories
  Precious Stones and Semi-Precious Stones.
• Precious Stones are the most rare gemstones and
  include diamonds, rubies, sapphires and emeralds.
• Semi-Precious Stones are more common and include
  amethysts, zircons, garnets, and topaz.
• Some gemstones are not minerals because they are
  formed through organic processes such as amber
  and pearls.

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Ch. 13-4 What Is A Rock

• Key Terms
• Rock
• Igneous
• Sedimentary
• Metamorphic
• Rock Cycle

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California Content Standards for Earth Science
Addressed

• Earth Science
• 3(c) Students know how to explain the properties
  of rocks based on the physical and chemical
  conditions in which they formed, including plate
  tectonic processes.

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Why Do I Need To Know This?

• So that you can better understand what is
  happening inside the Earth during volcanoes and
  earthquakes, which are major natural disasters.
• So that you can better understand how and why
  various minerals form to make informed decisions
  about our natural resources.
• So that you can understand some of the proof for
  plate tectonics.
• So that you can better understand how and why
  certain minerals form, especially if you want to
  buy such things as jewelry (or have it bought for
  you!)

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Key Sections Ch. 13-4

• Types of Rocks
• The Rock Cycle

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What Is A Rock?

• A Rock is a solid substance made up of 1 or more
  minerals.
• A rock can be made out of substances that do not
  fit all of the tests for a mineral (for example,
  amber is a rock, but not a mineral).
• Humans/hominids have been using rocks for tools
  and building things for over 2,500,000 years!

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Types of Rocks

• Rocks are placed into 3 groups according to how
  they form igneous, sedimentary and metamorphic.

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Igneous Rocks

• Igneous rocks form from melted
• rocks that come from inside the earth.
• Ignis, in Latin means fire.
• There are only about 100 types of igneous rocks
  in the world.

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Sedimentary Rocks

• Sedimentary Rocks form from sediment, or broken
  pieces of rock and organic matter that get
  compacted and cemented together
• There are only about 75 different types of
  Sedimentary Rocks in the world.

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Metamorphic Rocks

• Meta in Latin means change.
• Morphic in Latin means shape.
• Metamorphic Rocks form when heat and/or pressure
  change existing rocks into new types.
• There are over 2200 types of metamorphic rocks
  known to exist!

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The Rock Cycle (the basics)

• All new rocks start as igneous rocks.
• Over time they erode into particles, get moved
  away, and buried.
• At some point, they get buried so deep that they
  become stuck together (or cemented) and become
  sedimentary rocks (about 100 feet down).
• If the rocks become buried so deep, they will
  react chemically and become metamorphic rocks
  (about 1 mile down).
• If they get buried deep enough, they will begin
  to melt and become igneous rocks again (about 35
  miles down).

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The Rock Cycle (advanced)

• The rock cycle does not go in a perfect circle.
• Sometimes igneous rocks do not reach the surface
  of the Earth and instead become metamorphic
  rocks.
• Sometimes sedimentary rocks can get eroded again
  and form new sedimentary rocks.
• Sometimes metamorphic rocks can get become eroded
  and form new sedimentary rocks.
• Sometimes metamorphic rocks can continue to get
  buried and change into different metamorphic
  rocks.
• THE CYCLE IS ENDLESS IN POSSIBILITIES!!!!!!

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The Rock Cycle
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Ch. 13-5 Fluid and Fire Igneous Rocks

• Key Terms
• Extrusive Rock
• Intrusive Rock

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California Content Standards for Earth Science
Addressed

• Earth Science
• 3(c) Students know how to explain the properties
  of rocks based on the physical and chemical
  conditions in which they formed, including plate
  tectonic processes.

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Why Do I Need To Know This?

• Because volcanoes are cool!
• So you wont take everything a geologist says for
  granite!
• So that you can better understand plate tectonics.

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Key Sections Ch. 13-5

• None

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Igneous Rocks

• Igneous rocks are classified according to their
  composition and texture.
• Composition means what minerals make up the rock.
• Texture means the shape, size, arrangement and
  distribution of the minerals that make up the
  rock.
• Both the composition and texture of an igneous
  rock will change depending on where and how it
  forms.

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Igneous Rock Composition

• The composition of an igneous rock tell a lot
  about where the material came from.
• The composition can tell us if it comes from deep
  in the Earth or closer to the surface from melted
  crust material.

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Intrusive Igneous Rocks

• Intrusive igneous rocks form below the earths
  surface and consequently may not be seen.
• A pluton is a large intrusive rock that lifts up
  thousands of square miles.
• Intrusive igneous rocks tend to have coarse
  grained texture (big, inter-locking crystals).
• The most common intrusive igneous rock is granite.

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Extrusive Igneous Rocks

• These are igneous rocks that formed at the
  Earths surface.
• Extrusive rocks can have glassy, fine-grained or
  porphyritic textures.
• They may also show signs of lots of gas bubbles
  in them.
• The most common forms of extrusive igneous rocks
  are basalt and andesite.

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Ch. 13-6 Slowly Built Layers Sedimentary Rocks

• Key Terms
• Clastic Rock
• Chemical Rock
• Organic Rock

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Key Sections Ch. 13-6

• Clastic Rocks
• Organic Rocks
• Chemical Rocks

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California Content Standards for Earth Science
Addressed

• Earth Science
• 3(c) Students know how to explain the properties
  of rocks based on the physical and chemical
  conditions in which they formed, including plate
  tectonic processes.

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Why Do I Need To Know This?

• Because fossils are cool!
• So that you can better understand earth history
  and fossils.
• So that you can tell if your home is built in a
  geologically safe area.

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Sedimentary Rocks

• Sedimentary Rocks are classified into 3
  categories based on how they form
• Clastic Rocks
• Organic Rocks
• Chemical Rocks

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Clastic Rocks

• Clastic rocks are rocks that are made up of
  broken bits of other rocks.
• Clastic rocks form by being buried and cemented
  together.
• Clastic rocks are divided up based on how angular
  or rounded the broken bits are.
• Conglomerates are clastic rocks that are very
  round and often contain fossils!

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Organic Rocks

• Organic rocks are formed from the remains of
  living organisms.
• Organic rocks also contain large amounts of
  fossils.
• Organic rocks can be easily identified by pouring
  acid on them.
• One type of organic rock is limestone, which we
  use as chalk.

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Chemical Rocks

• Chemical rocks form when a sea or lake dries up.
• Two of the most common types of chemical rock are
  salt and gypsum.

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Ch. 13-7 Changes In Form Metamorphic Rocks

• Key Term
• Metamorphism

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Key Sections Ch. 13-7

• None

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California Content Standards for Earth Science
Addressed

• Earth Science
• 3(c) Students know how to explain the properties
  of rocks based on the physical and chemical
  conditions in which they formed, including plate
  tectonic processes.

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Why Do I Need To Know This?

• Because metamorphic rocks are pretty (and
  sometimes very expensive)!
• So that you can better understand earth history
  and plate tectonics.
• So that you can say you completed the rock cycle
  (wohoo!).

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Key Sections Ch. 13-7

• Types of Rocks
• The Rock Cycle

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Metamorphic Rocks

• Metamorphic rocks form when already existing
  rocks are buried deep within the Earth. The
  tremendous heat and pressure cause the rocks to
  undergo chemical reactions to create new
  minerals.
• Typically metamorphic rocks form between 100 and
  800 degrees Centigrade and thousands of times
  atmospheric pressure.
• Metamorphic rocks can be formed from any rock
  type (igneous, sedimentary, or even other
  metamorphic rocks).
• The minerals in metamorphic rocks can line up to
  show foliation.

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Metamorphism for Igneous Rocks

• Granite that is metamorphosed becomes gneiss.

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Metamorphism for Sedimentary Rocks

• Graphite becomes diamond.
• Limestone becomes marble.

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Metamorphism for Metamorphic Rocks

• Shale can metamorphose into Slate.
• Slate can metamorphose into Muscovite.
• Muscovite can metamorphose into Schist.