Rocks and Minerals

1
Rocks and Minerals
2
Quartz
Apatite
Diamond
hardness
color
Topaz
fracture
Gypsum
talc
Minerals
luster
Corundum
density
Orthoclase
Calcite
Fluorite
cleavage
3
EQ What is a mineral?

• Standard S6E5.b
• Investigate the contribution of minerals to rock
  composition.

4
EQ How are minerals identified?

• What are the characteristics of a mineral?
• How are minerals identified?
• What is the Mohs hardness scale?
• What is the major difference between an element
  and a compound?

5
Properties of Minerals

• A mineral is a naturally formed, inorganic solid
  that has a crystal structure and a definite
  chemical composition.
• Each mineral has its own set of specific physical
  properties that can be used to identify it
  (hardness, color, streak, luster, density,
  crystal system, cleavage and fracture).
• An element is a substance composed of a single
  kind of atom.
• A compound is two or more elements combined so
  that the elements no longer have their
  original distinct properties.

6
Properties of Minerals

• Naturally Formed- must form naturally
• Inorganic- cannot arise from materials that were
  once part of a living thing
• Solid- always solid, with a definite volume and a
  definite shape
• Crystalline Structure- particles must line up in
  a pattern that repeats over and over again
• Definite Chemical Composition- always contains
  certain elements in definite proportions. NaCl
  (salt)

7
Identifying Minerals

• Hardness- Mohs hardness scale ranks ten minerals
  from softest to hardest.
• Color- Because of factors, such as impurities,
  used only to identify a few minerals
• Streak- the color of a mineral in its powdered
  form
• Luster- how a mineral reflects light from its
  surface
• Density- the ratio of the mass to the volume of a
  substance
• Crystal Systems- six groups of structures based
  on the number and angle of the crystal faces
• Cleavage splitting along smooth, flat surface
• Fracture- breaking apart along curved or
  irregular surfaces

8
Special Properties

• Some properties are particular to only a few
  types of minerals
• Fluorescence glow under ultraviolet light
• Chemical Reactions reacts to an acid
• Magnetism natural magnets that attract iron.
• Taste ex. Halite has a salty taste
• Optical Properties some can cause a double
  image
• Radioactivity minerals that contain radium or
  uranium

9
Mohs Hardness Scale

• Talc 1 Softest known mineral
• Gypsum 2 fingernail can scratch it
• Calcite 3 scratched by copper penny
• Fluorite 4 easily scratched by steel knife
• Apatite 5 can be scratched by steel knife
• Orthoclase 6 can scratch window glass
• Quartz 7 can scratch steel
• Topaz 8 can scratch quartz
• Corundum 9 can scratch topaz
• Diamond 10 hardest known mineral

10
Quick Check

• 1. Which of the following is NOT a
  characteristic of a mineral?
• It is formed in nature.
• It is a living material.
• It has a crystalline structure.
• It is a solid.

11
Quick Check

• 2. Which of the following properties of minerals
  does Mohs scale measure?
• luster
• density
• hardness
• streak

12
Quick Check

• 3. Pure substances cannot be broken down into
  simpler substances by ordinary chemical means are
  called
• a. molecules.
• b. compounds.
• c. crystals.
• d. elements.

13
Quick Check

• 4. Which of the following properties is
  considered a special property that applies to
  only a few minerals?
• a. luster
• b. taste
• c. hardness
• d. density

14
Quick Check

• 5. Which of the following substances is a
  mineral?
• a. fluorite, which is a crystalline solid with
  the chemical formula CaF2
• b. coal, which forms from the remains of living
  things.
• c. obsidian, which is a volcanic glass and is
  not crystalline.
• d. brass, which is a metal that is made by
  humans.

15
EQ What is a mineral?

• What is a crystal, and what determines a
  crystals shape?
• Describe the two major groups of minerals.
• What is a native element?

16
Mineral Structure

• A mineral is a naturally formed, inorganic solid
  that has a define crystalline structure.
• Minerals may be either elements or compounds.
• Elements are pure substances that cannot be
  broken down into simpler substances by ordinary
  means.
• A compound is a substance made of two or more
  elements that have been chemically joined
  together.
• A mineral that is composed of only one element is
  called a native element.

17
Crystals

• A crystal is a solid whose atoms, ions, or
  molecules are arranged in a definite pattern.
• Crystals are solid, geometric forms produced by a
  repeating pattern of atoms or molecules that are
  present throughout the mineral.
• A crystals shape is determined by the
  arrangement of the atoms or molecules within the
  crystal.
• All minerals can be grouped into crystal classes
  according to the kinds of crystals they form.

18
Two Groups of Minerals

• Minerals are divided into two groups based on
  their chemical composition.
• Silicate minerals are minerals that contain a
  combination of the elements silicon and oxygen
  (quartz, feldspar, mica).
• Silicate minerals make up over 90 of the Earths
  crust.
• Nonsilicate minerals are minerals that do not
  contain a combination of the elements silicon and
  oxygen ( copper, calcite, fluorite, corundum,
  gypsum, galena).

19
Quick Check

• 1. What are the two major groups of minerals?
• metallic and nonmetallic
• native elements and carbonates
• silicates and nonsilicates
• quartz and mica

20
Quick Check

• 2. Silicate minerals contain a combination of
  the elements
• Sulfur and oxygen.
• Carbon and oxygen.
• Iron and oxygen.
• Silicon and oxygen.

21
Quick Check

• 3. Which of the following is a nonsilicate
  mineral?
• orthoclase, KASi3O8
• Talc, Mg3Si4O10(OH)2
• Almandine, Fe3Al2(SiO4)3
• Magnetite, Fe3O4

22
The Formation, Mining, and Use of Minerals (p.74)

• Where can you find minerals?
• What is an ore?
• Compare surface and subsurface mining.
• What is reclamation?
• What are some examples of minerals and their uses?

23
The Formation of Minerals

• Minerals form in a variety of environments in
  Earths crust.
• Each of these environments has a different set of
  physical and chemical conditions.
• The environment in which a mineral forms
  determines the minerals properties.
• Environments in which minerals form may be on or
  near Earths surface or deep beneath Earths
  surface.

24
The Environments

• Evaporating Salt Water
• When a body of salt water dries up, minerals are
  left behind.
• -gypsum, halite
• Metamorphic Rocks
• When changes in temperature, pressure, or
  chemical make-up changes a rock, metamorphism
  takes place.
• -calcite, garnet, graphite, hematite, magnetite,
  mica, and talc

25
The Environments

• Limestones
• Surface water and ground water carry dissolved
  materials to lakes and seas where they
  crystallize on the bottom
• -Calcite, dolomite
• Hot-Water Solutions
• Groundwater works its way downward and is heated
  by magma. It then reacts with minerals to form a
  hot liquid solution.
• -gold, copper, sulfur, pyrite, galena

26
The Environments

• Pegmatites
• As magma moves upward, it can form
  teardrop-shaped bodies called pegmatites. The
  mineral crystals become extremely large.
• -many gemstones, such as topaz, tourmaline
• Plutons
• As magma rises upward through the crust, it
  sometimes stops moving before it reaches the
  surface and cools slowly, forming millions of
  mineral crystals. The entire magma body
  solidifies to form a pluton.
• Mica, feldspar, magnetite, quartz

27
Mining

• An ore is the natural material large enough and
  pure enough to be mined for profit.
• Rocks and minerals are removed from the ground by
  one of two methods-surface mining and subsurface
  mining.
• Surface mining is used to remove mineral deposits
  on or near the Earths surface.
• - open pits
• - surface coal mines (open-pit)
• - quarries

28
Mining

• Subsurface mining is used when mineral deposits
  are located too deep within Earth to be surface
  mined.
• Mine reclamation is the process by which land
  used for mining is returned to its original state
  or better.
• Has been required by law since the mid-1970s.
• To reduce the effects of mining, reduce our need
  for minerals.
• Recycle!

29
The Use of Minerals

• Some minerals are of major economic and
  industrial importance.
• Metallic minerals have shiny surfaces, do not let
  light pass through them, good conductors of heat
  and electricity.
• Nonmetallic minerals have shiny or dull surfaces,
  may let light pass through them, and are good
  insulators of electricity.

30
The Use of Minerals

• Gemstones are highly valuable minerals because of
  their beauty and rarity rather than their
  usefulness.
• Color is the most important characteristic of a
  gemstone.
• The more attractive the color is, the more
  valuable the gem is.
• Mass of a gem is expressed in a unit known as a
  carat.
• One carat is equal to 200 mg.

31
Common Uses of Minerals
Mineral Uses
Copper Electrical wires, plumbing, coins
Diamond Jewelry, cutting tools, drill bits
Galena Batteries, ammunition
Gibbsite Cans, foil, appliances, utensils
Gold Jewelry, computers, spacecraft, dentistry
Gypsum Wallboards, plaster, cement
Halite Nutrition, highway de-icer, water softener
Quartz Glass, computer chips
Silver Jewelry, photography, electronic products
Sphalerite Jet aircraft, spacecraft, paints
32
Quick Check

• In a mineral, the particles line up in a
  repeating pattern to form
• A. an element
• B. a crystal
• C. a mixture
• D. a compound

33
Quick Check

• The term that describes how a mineral reflects
  light is its __________.
• A. luster.
• B. streak
• C. color.
• D. weight.

34
Quick Check

• One characteristic that a substance must have to
  be considered a mineral is _____.
• A. to be living.
• B. to be small.
• C. to a liquid.
• D. to be a solid.

35
Quick check

• A compound is two or more ________ chemically
  combined.
• A. atoms
• B. minerals
• C. elements
• D. protons

36
Quick Check

• An element is a substance composed of a single
  kind of __________.
• A. compound.
• B. atom.
• C. mineral.
• D. Mohs hardness scale.

37
Quick Check

• The groupings silicate and nonsilicate minerals
  are based on
• Organic content.
• Gas and liquid state
• Chemical composition.
• Color.

38
Quick Check

• Nonsilicate minerals
• Do not contain oxygen.
• Include native elements.
• All have a nonmetallic luster.
• Are all rare substances.

39
Quick Check

• Which of the following is NOT a class of
  nonsilicate minerals?
• oxides
• Micas
• carbonates
• native elements

40
Quick Check

• What is a mineral deposit that is large and pure
  enough to be mined called?
• gemstone
• ore
• pluton
• pegmatite

41
Quick Check

• Halides form when fluorine, chlorine, or bromine
  combine with any of the following elements EXCEPT
• sodium.
• potassium.
• calcium.
• oxygen.

42
Quick Check

• What is the name for nonmetallic minerals that
  are valued for their beauty and rarity rather
  than their usefulness?
• plutons
• gemstones
• ores
• pegmaites

43
Quick Check

• What kinds of mines are open pit and quarry
  mines?
• shaft mines
• slope mines
• surface mines
• subsurface mines

44
ROCK Mineral Mixtures
sediments
cooling
sedimentary
melting
erosion
magma
igneous
pressure
lava
metamorphic
cementation
heat
45
EQ How are rocks formed?

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

46
How are rocks classified?

• How are rocks classified?
• How does igneous rock become sedimentary rock?
• How does sedimentary rock become metamorphic
  rock?
• How does metamorphic rock become igneous rock?

47
Rock Formation

• Scientists classify rocks by the way they are
  formed.
• Rocks are composed of minerals and other
  materials.
• Minerals are the building blocks of rocks.
• Rocks are classified into three (3) groups based
  on how they are formed
• Sedimentary rocks
• Igneous rocks
• Metamorphic rocks

48
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.

49
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 color and texture
  and determine its mineral composition.
• 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.

50
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.

51
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.

52
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.

53
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 cementation.
• Metamorphic rock is formed by heat, pressure or
  chemical change beneath Earths surface.

54
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.

55
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 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 that
• have been 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

56
Quick Check

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

57
Quick Check

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

58
Quick Check

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

59
Quick Check

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

60
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?

61
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.

62
Origins of Igneous Rock

• Igneous rocks form from melted rock, the cooling
  and hardening of magma and lava.
• Magma is molten rock beneath Earths surface.
• Lava is molten rock above Earths surface.
• When a volcano erupts, magma is released onto
  Earths surface.
• Once above Earths surface, it is called lava.
• Common igneous rocks granite, basalt, pumice,
  obsidian.

63
Composition and Texture of Igneous Rock

• Igneous rocks differ from one another in what
  they are made of and how fast they are cooled.
• 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

64
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

65
Composition and Texture of Igneous Rock

• Igneous rocks differ from one another in what
  they are made of and how fast they are cooled.
• 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

66
Origin of Formation

• Igneous rock formations are located below and
  above Earths surface.
• Intrusive igneous rock from magma (below
  surface), coarse-grained (large crystals), below
  Earths surface
• Extrusive igneous rock from lava (above
  surface), fine-grained (small crystals), below
  Earths surface

67
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. They
  differ in mineral composition depending on how
  much silica and other minerals are present.
• Extrusive rock (basalt) forms from lava that has
  erupted onto Earths surface.
• Intrusive rock (granite) forms when magma hardens
  beneath Earths surface.
• Dark igneous rocks form from magma or lava low in
  silica content (felsic).
• Light igneous rocks form from magma high in
  silica content (mafic).

68
Composition and Texture of Igneous Rock

• The longer it takes for magma or lava to cool,
  the more time the crystals have to grow.
• The larger the crystals or grains, the more
  coarse the texture of the rock.
• The less time liquid rock takes to cool, the less
  time crystals have to grow.
• This type of rock will be fine-grained.
• Fine-grained rocks contain very small crystals or
  grains.
• If the cooling is very rapid, it contains no
  crystals.

69
Intrusive Igneous Rock

• Igneous rock that forms below the surface of the
  earth
• Below intrusive
• Usually has coarse-grain texture
• Cools very slowly
• Common intrusive igneous rocks are called Plutons.

70
Extrusive Igneous Rock

• Igneous rock that forms above the earths surface
• Extrusive above
• Common around volcanoes
• Cools quickly
• Usually fine-grained texture
• Lava cools to form the ocean floor

71
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.

72
Summary

• Igneous rock forms when magma cools and hardens
• The texture of igneous rock is determined by the
  rate at which the rock cools
• Igneous rock that solidifies at Earths surface
  is extrusive. Igneous rock that solidifies
  within Earths surface is intrusive.

73
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

74
Quick Check

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

75
Quick Check

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

76
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

77
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

78
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.

79
Forming of Sedimentary Rock

• Sedimentary rocks are formed when particles of
  other rocks or the remains of plants and animals
  are pressed and cemented together.
• Rocks undergo weathering to form sediment.
• Sediment is transported (erosion), settled out of
  the wind and water and deposited somewhere.
• Usually after burial somewhere, the deposited
  sediment undergoes lithification.

80
Forming of Sedimentary Rock

• Lithification is the process that turns sediment
  into a rock.
• If the sedimentary rock is buried deep in to the
  crust under more and more sediment (layered),
  often due to plate tectonics, the heat and
  pressure causes metamorphism to occur.
• This transforms the sedimentary rock into a
  metamorphic rock.
• Sediment (weathering) erosion deposited
  compaction cementation.
• Common Sedimentary Rock sandstone, shale, and
  limestone.

81
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.

82
Forming of Sedimentary Rock

• Sedimentary rocks are formed when small particles
  of rock and the remains of plants and animals are
  compacted and cemented together.
• To form sedimentary rocks, sediment is loosened
  and carried away by water and wind by erosion.
• The sediment then settles out of the wind and
  water during deposition.
• The sediment begins to settle out and form
  layers. As the layers stack up, they become
  heavier until the weight squeezes the layers
  tighter during compaction.

83
Composition of Sedimentary Rock

• Sedimentary rock is classified by the way it
  forms.
• Clastic formed from other rocks and minerals
  (conglomerate, sandstone, shale)
• Chemical forms when minerals crystallize out of
  solutions (halite)
• Organic forms from the remains of once-living
  things (limestone).

84
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.

85
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

86
Clastic Rock Shale

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

87
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.

88
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.

89
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

90
Organic Rock Coal

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

91
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.

92
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

93
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.

94
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.

95
Summary

• Sedimentary rock forms from rock weathering into
  sediment, erosion, deposition, compaction and
  cementation.
• Sedimentary rock forms at or near the Earths
  surface.
• Clastic sedimentary rock forms when rock or
  mineral fragments are cemented together.
• Chemical sedimentary rock forms from solutions of
  dissolved minerals and water.
• Organic (limestone) forms from the remains of
  plants and animals.

96
Quick Check

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

97
Quick Check

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

98
Quick Check

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

99
Quick Check

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

100
Quick Check

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

101
Quick Check

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

102
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.

103
Metamorphic Rocks

• Metamorphic rock is formed when existing rock is
  changed by heat, pressure, or chemical reactions.
• They are classified by the arrangement of their
  mineral grains.
• The two types of metamorphic rocks are called
  foliated and non-foliated.
• Foliated is when the grains are parallel or
  arranged in planes or bands.
• Non-foliated refers to where the grains are
  arranged randomly.

104
How Do Metamorphic Rocks Form?

• Heat and pressure deep beneath Earths surface
  can change any rock into metamorphic rock.
• When a rock changes into metamorphic rock, its
  texture, crystal structure, and mineral content
  change.
• 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.

105
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.

106
Textures of Metamorphic Rock

• Geologists classify metamorphic rocks by the
  arrangement of the grains that make up the rocks.
• Metamorphic rocks that have their grains arranged
  in layers or bands are foliated.
• Examples
• Slate (from shale)
• Schist
• Gneiss (from granite)

107
Textures of Metamorphic Rock

• Nonfoliated rocks grains are arranged randomly.
• Examples
• Marble (from limestone)
• Quartzite (from sandstone)
• Metamorphic rocks are harder and more dense than
  sedimentary rocks.

108
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.

109
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.

110
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 change.
• Forces inside Earth and at the surface produce a
  rock cycle that builds, destroys, and changes the
  rocks in the crust.

111
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

112
Quick Check

• 2. Molten rock beneath Earths surface is called
• A. Lava.
• B. Magma.
• C. Sedimentary rock.
• D. Igneous rock.

113
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

114
Quick Check

• 4. Which of the following is a metamorphic rock?
• A. Granite
• B. Sandstone
• C. Limestone
• D. marble

115
Quick Check

• 5. Metamorphic rocks can be formed from
• A. igneous rocks.
• B. sedimentary rocks.
• C. metamorphic rocks.
• D. all rock groups.

116
Quick Check

• 6. The rock formed when granite changes to a
  metamorphic rock is
• A. marble.
• B. basalt.
• C. gneiss.
• D. pumice.

117
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.

118
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.

119
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.

120
Quick Check

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

121
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 __________.

122
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

123
Quick Check

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

124
Quick Check

• 16. Igneous rocks forms 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.

125
Quick Check

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

126
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.

127
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.

128
Processes of Change
weathering
mechanical weathering
chemical weathering
moving water
deposition
waves
glaciers
gravity
wind
erosion
129
The Crust, Mantle, and CoreLesson 16

• How do the forces within the earth affect the
  formations of the Earths surface?

130
The Crust, Mantle, and Core

• Earth is divided into four layers the crust, the
  mantle, the outer core, and the inner core.
• Each layer is made up of different materials.
• It takes 6,380 kilometers to get to the center of
  the Earths inner core.
• Each layer has a different thickness.

131
Thickness of Earths Layers

• Crust 8-32 kilometers
• Mantle 2900 kilometers
• Outer Core 2250 kilometers
• Inner Core 1300 kilometers

132
The Crust

• The crust is the thin outer layer of Earth.
• Earths crust is made of two layers.
• The top layer is made of granite the bottom
  layer is made of basalt.
• The continents are made of both granite and
  basalt.
• The ocean floors are made of basalt.

133
The Mantle

• The makeup of the mantles rocks is similar to
  that of the crust.
• The Moho boundary is located between the crust
  and the mantle.
• Currents of the mantles molten rock can move
  whole continents and ocean floors.
• Molten rock from the mantle burst through the
  crust to create islands and volcanoes.
• The top layer of the mantle is liquid rock that
  we call the asthenosphere.

134
The Outer and Inner Cores

• Earths core is made up of two parts a shell
  called the outer core and a sphere called the
  inner core.
• Both cores are made up of the metals iron and
  nickel.
• The outer core is liquid metal the inner core is
  solid metal.
• Tremendous pressure keeps the inner core a solid.

135
Quick Check

• The very top layer of Earth, found under soil and
  water is which of the following
• a. upper mantle
• b. crust
• c. asthenosphere
• d. outer core

136
Quick Check

• Which of the following causes the difference
  between the upper mantle and lower mantle?
• a. heat
• b. pressure
• c. erosion
• D. weathering

137
Quick Check

• The pressure on the inner core can be compared to
  which of the following
• a. The same pressure as the pressure around
  an exploding bomb.
• b. The same pressure as the pressure of a
  volcano erupting.
• c. The same pressure as the pressure of
  hurricane wind.

138
Quick Check

• The inner core is made of
• a. liquid metal
• b. liquid rock
• c. solid metal

139
Quick Check

• The reason we have a magnetic field is due to
  the
• a. gravitational pull of the sun.
• b. gravitational pull of Earth.
• c. movement of the inner core.
• d. movement of the outer core.

140
Quick Check

• From the lowest to highest temperature, which is
  the correct order of Earths layers?
• A. inner core, outer core, mantle, crust
• B. mantle, crust, outer core, inner core
• C. crust, mantle, outer core, inner core
• D. crust, mantle, inner core, outer core

141
Quick Check

• In general, how does the density of material in
  Earths layers change with depth?
• a. density increases with depth
• b. density decreases with depth
• c. density does not change with depth
• d. density increases, then decreases with
  depth

142
Quick Check

• In Earths crust, what type of rock is found
  under the oceans?
• a. only granite
• b. only basalt
• c. granite on top, basalt underneath
• d. basalt on top, granite underneath

143
Quick Check

• The thickest layer of the Earth is the
• a. crust.
• b. mantle.
• c. outer core.
• d. inner core.

144
Quick Check

• The Moho is the boundary between the
• a. inner and outer core.
• b. the outer core and the mantle.
• c. the crust and the mantle.
• d. the crust and the atmosphere.

145
Quick Check

• What is the composition of the core?
• A ______________________________
• What is the composition of the asthenosphere and
  where is it located?
• A ________________________________
• _________________________________
• _________________________________

146
Quick Check

• Compare the temperature of Earths four (4)
  layers.
• Crust ______________________________
• Mantle _____________________________
• Outer Core _________________________
• Inner Core __________________________

147
Quick Check

• Inside the Earth, What increases with depth?
• A ______________________________
• _______________________________
• _______________________________

148
EQ

• How does weathering
• occur?

149
Weathering

• Describe three ways abrasion occurs in nature.
• List three things that cause chemical weathering
  of rocks.
• Describe the similarity in the ways tree roots
  and ice mechanically weather rock.
• Describe five (5) sources of chemical weathering.

150
Weathering

• Weathering is the process by which rock materials
  are broken down by the action of physical or
  chemical processes.
• Mechanical weathering is the breakdown of rock
  into smaller pieces by physical means. (ice,
  wind, water, gravity, plants, animals)
• Chemical weathering is the process by which rocks
  break down as a result of chemical reactions.
  Water, weak acids, and air can cause chemical
  weathering.

151
6 Agents of Mechanical Weathering

• 1. Ice water seeps into cracks during warm
  weather. When the temperature drops, the water
  freezes and expands, causing the ice to push
  against the sides of the crack. This causes the
  crack in the rock to widen.
• Abrasion the grinding and wearing away of rock
  surfaces through mechanical action of other rock
  or sand pebbles.
• The three ways that can cause abrasion are wind,
  water, and gravity.

152
Three Causes of Abrasion

• 2. Water as rocks and pebbles roll along the
  bottom of flowing water, they bump and scrape
  against each other, causing these rocks to become
  rounded and smooth.
• 3. Wind wind blows sand and silt against
  exposed rock eventually wearing away the rocks
  surface.
• 4. Gravity rocks grind against each other
  during a rock slide, creating smaller and smaller
  rock fragments. Anytime one rock hits another
  rock, abrasion takes place.

153
Plants and Animals

• Some plants (6) can easily break rocks. The
  roots grow through existing cracks in rocks.
• The growth causes the root to expand, forcing
  the crack to widen. The force can eventually
  split the rock apart.
• 7. Animals that live in the soil (moles, prairie
  dogs, insects, worms, gophers), cause a lot of
  weathering. By burrowing in the ground, these
  living creatures brake up soil and loosen rocks
  to be exposed to further weathering.

154
5 Agents of Chemical Weathering

• Common agents of chemical weathering are water,
  acids, and air.
• These agents weaken the bonds between minerals
  grains of the rock.
• 1. Water can cause rock to be broken down and
  dissolve. Can take thousands of years to take
  place.
• 2. Air the process of oxidation is a chemical
  reaction in which an element (iron) combines with
  oxygen, causing rust.
• (Weak Acids) - acid precipitation, acids in
  groundwater, acids in living things.

155
Three Sources of Weak Acids

• 3. Acid Precipitation rain, sleet, or snow that
  contains a high concentration of acid. Normal
  precipitation is acidic, acid precipitation
  contains more acid than normal.
• 4. Acids in Groundwater carbonic acid or
  sulfuric acid reacts with rocks in the ground,
  causing a chemical reaction, eating away at the
  rock.
• 5. Acids in Living Things Lichens produce acids
  that slowly break down rock.

156
Summary

• Ice wedging is a form of mechanical weathering in
  which water seeps into rock cracks and then
  freezes and expands.
• Wind, water, and gravity cause mechanical
  weathering by abrasion.
• Animals and plants cause mechanical weathering by
  turning the soil and breaking apart rocks.
• Water, acids, and air chemically weather rock by
  weakening the bonds between mineral grains of the
  rock.

157
Quick Check

• 1. Which of the following things cannot cause
  mechanical weathering?
• A. water
• B. acid
• C. wind
• D. animals

158
Quick Check

• 2. Which of the following is a type of frost
  action?
• A. abrasion
• B. oxidation
• C. ice wedging
• D. gravity

159
Quick Check

• 3. Which of the following types of chemical
  weathering causes a karst landscape, such as a
  cavern?
• A. lichens
• B. acid precipitation
• C. acids in groundwater
• D. water

160
Quick Check

• 4. How do lichens slowly break down a rock?
• A. by abrasion
• B. by mechanical means
• C. by ice wedging
• D. by chemical means

161
Quick Check

• 5. Which of the following will most likely
  experience oxidation?
• A. tennis ball
• B. aluminum can
• C. wooden fence
• D. Bicycle tire

162
Quick Check

1. The grinding and wearing away of rock surfaces
   through the mechanical action of other rock or
   sand particles
2. Rain, sleet, or snow that contains a high
   concentration of acids
3. The process by which rocks break down as a result
   of chemical reactions
4. The breakdown of rock into smaller pieces by
   physical means
5. A chemical reaction in which an element, such as
   iron, combines with oxygen to form an oxide
6. The process by which rock materials are broken
   down by the action of physical or chemical
   processes

• a. mechanical weathering
• b. oxidation
• c. weathering
• d. acid precipitation
• e. abrasion
• f. chemical weathering

163
Rates of Weathering

• What is differential weathering?
• How does surface area affect the rate of
  weathering?
• How does climate affect the rate of weathering?
• Why do mountaintops weather faster than rocks at
  sea level?

164
Differential Weathering

• Differential weathering is a process by which
  softer, less weather resistant rocks wear away
  and leave harder, more weather resistant rocks
  behind.
• Hard rocks weather more slowly than softer rocks.

165
The Shape of Rocks

• Weathering takes place on the outer surface of
  rocks.
• The more surface area exposed to weathering, the
  faster the rock will be worn down.
• As the surface area increases, the rate of
  weathering also increases.
• If a large rock is broken into smaller pieces,
  weathering of the rock happens much faster.
• The rate of weathering increases because a
  smaller rock has more surface area to volume than
  a larger rock.
• More of the smaller rock is exposed to the
  weathering process.

166
Weathering and Climate

• The rate of chemical weathering is faster in
  warm, humid climates than cold, dry climates
  because of oxidation.
• Oxidation happens when the temperature is higher
  and when water is present.
• Water increases the rate of mechanical (physical)
  weathering (ice wedging).
• Repeated changes in temperature (freeze, thaw,
  freeze, thaw) is a major factor in mechanical
  weathering.

167
Weathering and Elevation

• Mountaintops weather faster than rocks at sea
  level because they are exposed to more wind,
  rain, and ice than rocks at sea level or lower
  elevations.
• The increase in wind, rain, and ice increases the
  effects of mechanical and chemical weathering.
  This increase in elevation causes peaks of
  mountains to weather faster.
• Gravity affects the rate of weathering
• Steepness
• Rainwater
• Removal of sediment exposes new rock to
  weathering
• Abrasion
• Increased surface area of mountain

168
Summary

• Hard rocks weather more slowly than softer rocks.
• The more surface area of a rock that is exposed
  to weathering, the faster the rock will be worn
  down.
• Chemical weathering occurs faster in warm, humid
  climates.
• Weathering occurs faster at high elevations
  because of an increase in ice, rain, and wind.

169
Quick Check

• A process by which softer, less weather-resistant
  rocks wear away and leave harder, more
  weather-resistant rocks behind is called
• A. differential weathering
• B. mechanical weathering
• C. chemical weathering
• D. ice wedging

170
Quick Check

• Which of the following statements describe a rock
  change after it is in a riverbed for a long
  period of time?
• A. The rock rapidly breaks into smaller pieces.
• B. Chunks of the rock break off, and the rock
  becomes rougher.
• C. The edges of the rock are worn away, so its
  surface becomes smoother.
• D. The rock absorbs water from the riverbed and
  becomes softer.

171
Quick Check

• Small rocks weather more quickly than larger
  rocks because their surface area is
• A. thinner.
• B. larger.
• C. smaller.
• D. thicker.

172
Quick Check

• The average weather condition in an area over a
  long period of time is called
• A. temperature.
• B. climate.
• C. weather.
• D. humidity.

173
Quick Check

• Chemical weathering is most rapid in areas that
  are
• A. hot and dry.
• B. warm and wet.
• C. cold and dry.
• D. cool and wet.

174
Quick Check

• Which rocks are exposed to more wind, rain, and
  ice?
• A. rocks at a lower elevation
• B. rocks at a higher elevation
• C. rocks in streams
• D. rocks in warm, humid climate

175
From Bedrock to Soil

• What is soil (loam) formed from?
• What is bedrock?
• What is soil structure?
• What is humus?
• What are soil horizons?

176
The Source of Soil

• Soil is a loose mixture of small mineral
  fragments, organic matter, water, and air that
  can support the growth of vegetation.
• Bedrock is the layer of rock beneath soil.
• Parent rock is the rock formation that is the
  source of soil.
• Wind, water, and movements of glaciers can
  transport or move soil from one place to another.

177
Soil Properties

• Soil is made from different-sized materials.
• Soil texture is the soil quality is based on the
  proportions of soil particles.
• Soil texture can influence the ability of water
  move through the soil.
• Soil structure is the arrangement of soil
  particles.

178
Soil Properties

• Some soils are rich in nutrients, some are poor
  in nutrients.
• A soils ability to hold nutrients and to supply
  nutrients to a plant is describe as soil
  fertility.
• Humus is the dark, organic material formed in
  soil from the decayed remains of plants and
  animals.

179
Soil Horizons

• Soil horizons are the horizontal layers of soil.
• The top layer of soil is called topsoil,
  containing more humus than the other layers of
  soil, rich in nutrients plants need to be
  healthy.
• Good topsoil is necessary for farming.

180
Summary

• Soil (loam) is formed from the weathering of
  bedrock.
• Soil texture affects how soil can be worked for
  farming and how well water passes through it.
• The ability of soil to provide nutrients so that
  plants can survive and grow is called soil
  fertility.

181
Quick Check

• Soil quality based on the relative size of soil
  particles is called
• A. residual soil.
• B. soil structure.
• C. soil texture.
• D. soil particles.

182
Quick Check

• What is the arrangement of soil particles called?
• A. soil structure
• B. soil texture
• C. soil particles
• D. infiltration

183
Quick Check

• What is the organic material formed in soil from
  the decayed remains of plants and animals called?
• A. bedrock
• B. parent rock
• C. residual soil
• D. humus

184
Quick Check

• Soil is important because it provides
• A. housing for animals
• B. Nutrients for plants
• C. storage for water
• D. All of the above

185
(No Transcript)
186
Quick Check

• Naomi made the pie graph during a laboratory
  experiment in which she analyzed the composition
  of loam (soil) found in Georgia. Based on this
  chart, which of the following is a valid
  conclusion?
• A. Approximately 95 of the material that makes
  up loam is useless to plants.
• B. Decayed organic matter is the least abundant
  component of loam.
• C. Only about 90 of loams composition is useful
  to plants.
• D. Only about 16 of loams composition is useful
  to plants.

187
Soil Conservation

• Why is soil important?
• How can human activity affect soil erosion?
• What are three important benefits that soil
  provides?
• List five methods of soil conservation.

188
Soil Conservation

• Soil can be endangered, just like plants and
  animals.
• It takes thousands of years for soil to form, it
  is not easy to replace.
• Soil conservation is a method to maintain the
  fertility of the soil by protecting the soil from
  erosion and nutrient loss.

189
The Importance of Soil

• Soil provides minerals and other nutrients for
  plant life.
• All animals get their energy from plants.
• Soil also provides a place for animals to live.
• The region a plant or animal lives is called a
  habitat.
• Soil holds water for plants to get the moisture
  or nutrients they need.

190
The Processes of Change

• Lesson 18

191
Processes of Change (5)

• Weathering and erosion wear down, deposition
  fills in Earths surface.
• Weathering is the slow wearing away or breaking
  down