EQ: How are rocks formed?

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EQ How are rocks formed?

• Standard S6E5.c
• Classify rocks by their process of formation.

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Classifying Rocks

• Classifying Rocks - How Geologists Classify
  Rocks When studying a rock sample, geologists
  observe the rocks origin, color and texture, and
  determine its mineral composition
• A. Origin 3 major groups of rocks
• 1. igneous rock forms from the cooling and
  hardening of molten rock
• a. lava above the surface
• b. magma below the surface
• 2. sedimentary rock forms in layers from
  other rocks, plants, and animals through a
  process of weathering, erosion, deposition,
  compacted and cemented together
• 3. metamorphic rock formed when existing
  rock is changed by heat, pressure, or
  chemical reactions
• B. Texture the size, shape, and pattern of the
  rocks grains
• 1. Grain Size
• a. fine-grained (small)
• b. coarse-grained (large)
• 2. Grain Shape
• a. smooth and rounded
• b. jagged
• 3. Grain Pattern
• a. lie in flat layers
• b. wavy, swirling patterns
• c. looks like rows of multicolored beads
• d. occur randomly

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Classifying Rocks

• I. Classifying Rocks - How Geologists Classify
  Rocks When studying a rock
  sample, geologists observe
  the rocks origin, color and
  texture, and determine its mineral
  composition
• A. Origin 3 major groups of rocks
• 1. igneous rock forms from the cooling and
  hardening of molten rock
• a. lava above the surface
• b. magma below the surface
• 2. sedimentary rock forms in layers from
  other rocks, plants, and animals through
  a process of weathering, erosion,
  deposition, compaction and cementation
• 3. metamorphic rock formed when existing
  rock is changed by heat, pressure, or
  chemical reactions

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• B. Texture the size, shape, and pattern of
  the rocks grains
• 1. Grain Size
• a. fine-grained (small)
• b. coarse-grained (large)
• 2. Grain Shape
• a. smooth and rounded
• b. jagged
• 3. Grain Pattern
• a. lie in flat layers
• b. wavy, swirling patterns
• c. looks like rows of multicolored
  beads
• d. occur randomly
• 4. No Visible Grain
• a. have no apparent grains
• b. smooth, shiny texture

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• C. Mineral Composition
• 1. mafic dark-colored rocks
• (poor in silica)
• 2. felsic light-colored rocks (rich
  in silica)

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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?

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What materials are rocks made of?

• 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 rocks origin, color and texture and
  determine its mineral composition.

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What materials are rocks made of?

• 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 rocks 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

• 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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Processes That Shape the Earth

• Certain geological processes make and destroy
  rock.
• These processes shape the features of the Earth.
• Theses processes also influence the type of rock
  that is found in a certain area of Earths
  surface.

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Processes That Shape the Earth

• 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 Earths surface.

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Illustrating the Rock Cycle

• 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 beneath Earths surface.

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Rock Classification

• 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.

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Quick Check

• Which of the following rocks is not normally used
  as a construction material?
• marble
• halite
• limestone
• granite

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Quick Check

• 2. The process in which wind, water, ice, and
  heat break down rock is called
• uplift.
• intrusion.
• recystallization.
• weathering.

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Quick Check

• 3. What forms when rock partially or completely
  melts?
• limestone
• reefs
• ripple marks
• magma

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Quick Check

• 4. Scientists classify rocks
• by composition and texture.
• by volume.
• by mass.
• by color and size.

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Quick Check

• Solid mixture of one or more minerals and organic
  matter
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. deposition

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Quick Check

• Process by which new rock forms from old
• rock
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. deposition

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Quick Check

• Process by which sediment is removed from its
  source
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. depositi

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Quick Check

• Process by which sediment is dropped and comes to
  rest
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. depositi

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Quick Check

• The chemical makeup of a rock
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. depositi

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Quick Check

• Size, shape, and position of grains that make up
  a rock
• a. composition
• b. rock
• c. erosion
• d. texture
• e. rock cycle
• f. depositi

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How do igneous rocks form?

• What characteristics are used to classify igneous
  rocks?
• Describe three (3) ways in which igneous rocks
  differ?
• 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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Origins of Igneous Rock

• Igneous rocks are classified by their origin of
  formation, texture of the grains, and composition
  of the rock.
• Igneous rock forms when magma cools and hardens.
• Three ways magma can form
• heat/rise in temperature
• pressure released
• rock changes composition

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Composition and Texture of Igneous Rock

• Igneous rocks differ from one another in what
  they are made of, how fast they are cooled and
  where the rocks form.
• Composition
• Igneous rock that is rich in silicon and
  light-colored are called felsic rock.
• Igneous rock that is poor in silicon and
  dark-colored are called mafic rock.
• Texture
• Fine-grained (small) cools quickly
• Coarse-grained (large) cools slowly

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Origin of Formation

• Igneous rock formations are located below and
  above Earths surface.
• Intrusive igneous rock Intrusive rock (granite)
  forms when magma hardens (beneath) Earths
  surface.
• coarse-grained (large crystals)
• below Earths surface
• ex. granite
• Extrusive igneous rock Extrusive rock (basalt)
  forms from lava that has erupted (onto) Earths
  surface.
• fine-grained (small crystals)
• on the Earth's surface
• ex. basalt

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How do igneous rocks form?

• Igneous rocks are classified according to their
  origin, texture, and mineral composition.
• Igneous rocks form either from lava, above the
  earths surface or magma, below the earths
  surface.
• They also differ in texture according to the size
  and shape of their mineral grains.
• Igneous rocks differ in mineral composition
  depending on how much silica and other minerals
  are present.
• Dark igneous rocks form from magma or lava low in
  silica content (mafic).
• Light igneous rocks form from magma high in
  silica content (felsic).
• Light-colored rocks are less dense than the
  dark-colored rocks.

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Uses of Igneous Rock

• 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.
• Perlite is often mixed with soil for strating
  vegetable seeds.

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Quick Check

• 1. Which of the following are ways magma is
  formed?
• by compaction and cooling
• by melting and cooling
• by changes in composition
• by weathering and erosion

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Quick Check

• What kind of texture does igneous rock have when
  magma cools slowly?
• coarse-grained
• large-grained
• fine-grained
• medium-grained

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Quick Check

• 3. What kind of texture does igneous rock have
  when magma cools rapidly?
• coarse-grained
• medium-grained
• large-grained
• fine-grained

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Quick Check

• 4. What kind of rock is formed when magma
  intrudes into other rock?
• extrusive igneous rock
• sedimentary rock
• intrusive igneous rock
• organic sedimentary rock

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Quick Check

• 5. What kind of rock is formed from lava that
  cools on Earths surface?
• a. organic sedimentary rock
• b. sedimentary rock
• c. intrusive igneous rock
• d. extrusive igneous rock

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How is sedimentary rock formed?

• Describe the origin of sedimentary rock.
• Describe the three main categories of sedimentary
  rock.
• Describe three types of sedimentary structures.

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What is sedimentary rock?

• 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.

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Forming of Sedimentary Rock

• Erosion occurs when running water or wind
  loosen and carries away fragments of rock.
• Deposition- the process in which sediment settles
  out of the water or wind carrying it.
• Compaction- the process that presses sediment
  together.
• Cementation- the process in which minerals
  crystallize and glue particles of sediment
  together.

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Types of Sedimentary Rock

• 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.

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Clastic Rocks

• A clastic rock is a sedimentary rock that forms
  when rock particles are squeezed together.
• Examples of clastic rocks
• Shale
• Sandstone
• Conglomerate
• Breccia

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Clastic Rock Shale

• Shale forms from tiny particles of clay.
• Shale feels smooth, and splits easily into flat
  pieces

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Clastic Rock Sandstone

• 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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Clastic Rock Conglomerate and Breccia

• Conglomerate is a rock made up of large particles
  with rounded edges.
• Breccia is a rock made up of large fragments with
  sharp edges.

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Organic Rocks

• Organic rock forms from the remains of plants and
  animals and are deposit in thick layers.
• The term organic refers to substances that were
  once part of living things.
• Three important organic rocks
• Coal
• Limestone
• Chalk

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Organic Rock Coal

• Coal forms from the remains of swamp plants
  buried in water.
• Over millions of years, they slowly change into
  coal.

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Organic Rock Limestone

• 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 Rocks

• Chemical rock forms when minerals that are
  dissolved in a solution crystallize.
• Chemical rocks can also form when mineral
  deposits left when seas or lakes evaporate.
• Examples
• Rock salt
• gypsum

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Sedimentary Rock Structures

• The most important feature of sedimentary rock is
  stratification.
• Stratification is the process in which
  sedimentary rocks are arranged in layers.
• Strata differ from one another depending on the
  kind, size, and color of their sediment.
• Ripple marks (1) are made by the motion of wind
  and water waves on lakes, oceans, rivers, and
  sand dues.
• Mud cracks (2) form when fine-grained sediments
  at the bottom of a shallow body of water are
  exposed to air and dry out.
• Rain-drop (3) impressions can be preserved in
  fine-grained sediments, as small pits with raised
  rims.

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Uses of Sedimentary Rocks

• 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.

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Quick Check

• 1. Which process forms sediment?
• weathering
• cementation
• compaction
• deposition

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Quick Check

• 2. What are strata?
• mineral fragments
• minerals crystallized out of solution
• layers in sedimentary rock
• fossils in sedimentary rock

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Quick Check Sedimentary Rock

• 3. What kind of sedimentary rock is made of
  fragments of rocks cemented together by a
  mineral?
• organic
• stratified
• chemical
• clastic

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Quick Check

• 4. What kind of sedimentary rock is made from
  solutions of dissolved minerals in water?
• organic
• chemical
• stratified
• clastic

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Quick Check

• 5. What kind of sedimentary rock is made from
  fossils?
• organic
• stratified
• chemical
• clastic

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Quick Check

• 6. What is the process called in which
  sedimentary rocks are arranged in layers?
• erosion
• extrusion
• weathering
• stratification

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How is metamorphic rock formed?

• How are metamorphic rocks formed?
• Describe two ways a rock can undergo
  metamorphism.
• Describe the difference between foliated and
  nonfoliated metamorphic rock.

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How Do Metamorphic Rocks Form?

• Metamorphic rock is formed when existing rock is
  changed by heat, pressure, or chemical reactions.
• Heat and pressure deep beneath Earths surface
  can change any rock into metamorphic rock.
• Metamorphic rocks are classified by the
  arrangement of their mineral grains.

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Textures of Metamorphic Rock

• 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.
• gneiss (from granite)
• Slate (from shale)
• Non-foliated rock refers to where the grains are
  arranged randomly.
• Marble (from limestone)
• Quartzite (from sandstone)

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Foliated Metamorphic Rock

• Gneiss
• Schist

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Nonfoliated Metamorphic Rocks

• Quartzite
• Marble

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Composition of Metamorphic Rock

• Metamorphism occurs when temperature and pressure
  inside the Earths crust change.
• Minerals that were present in the rock when it
  formed may not be stable in the new temperature
  and pressure conditions.
• The original minerals change into minerals that
  are more stable in these new environment.
• Some metamorphic minerals form only at certain
  temperatures and pressures.
• Common metamorphic rock slate, schist, marble,
  and gneiss.

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Metamorphic Rocks

• The texture or mineral composition of a rock can
  change when its surroundings change.
• If the temperature or pressure of the new
  environment is different from the one in which
  the rock formed, the rock will undergo
  metamorphism.
• Two ways that rock can undergo metamorphism are
  by contact metamorphism and regional
  metamorphism.
• Contact metamorphism happens near bodies of
  magma.
• Regional metamorphism occurs within Earths crust
  when pressure builds up in rock very deep below
  other rock formations

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Metamorphic Rock Structures

• Metamorphic rock has features that tell you about
  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 structures
  that indicate that a rock has been deformed.

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Uses of Metamorphic Rock

• Marble and slate are the two most useful
  metamorphic rocks.
• Marble can be cut into thin slabs and easily
  polished (Taj Mahal).
• Slate , because it is foliated, splits easily
  into flat pieces.
• Slate is used for flooring, roofing, outdoor
  walkways, or chalkboards.
• Marble and Slate both come in a variety of colors.

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Summary

• 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.

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Quick Check

• 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

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Quick Check

• 2. Molten rock beneath Earths surface is called
• a. lava.
• b. magma.
• c. sedimentary rock.
• d. igneous rock.

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Quick Check

• 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
  the rock
• d. let the rock stand under water for a long time

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Quick Check

• 4. Which of the following is a metamorphic rock?
• a. granite
• b. sandstone
• c. limestone
• d. marble

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Quick Check

• 5. Metamorphic rocks can be formed from
• a. igneous rocks.
• b. sedimentary rocks.
• c. metamorphic rocks.
• d. all rock groups.

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Quick Check

• 6. The rock formed when granite changes to a
  metamorphic rock is
• a. marble.
• b. basalt.
• c. gneiss.
• d. pumice.

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Quick Check

• 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.

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Quick Check

• 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.

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Quick Check

• 9. 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.

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Quick Check

• 10. Which type of rock is MOST LIKELY to form
  layers?
• A. Sedimentary
• B. Igneous
• C. Metamorphic
• D. magma

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Quick Check

• 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 __________.

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Quick Check

• 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

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Quick Check

• 15. An igneous rock that cools very slowly has a
  __________ texture.
• a. foliated
• b. fine-grained
• c. nonfoliated
• d. coarse-grained

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Quick Check

• 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.

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Quick Check

• 17. A __________ is a common structure found in
  metamorphic rock.
• a. ripple mark
• b. fold
• c. sill
• d. layer

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Quick Check

• 18. The process in which sediment is removed from
  its source and transported is called
  ____________.
• a. deposition.
• b. erosion.
• c. weathering.
• d. uplift.

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Quick Check

• 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.