Planet Earth

1
Planet Earth

• Chapter 17

2
Earths Interior and Plate Tectonics

• 17-1

3
Earths Interior

• Earth is made up of three primary layers each
  with its own unique composition and properties.
• The Crust - the solid, outermost and thinnest
  layer. It makes up only 1 of Earths volume.
  There are two types of crust.
• Continental crust thicker, exposed crust
• Deepest under mountains
• Oceanic crust thinner and more dense than
  continental crust

4
Earths Interior

• The Mantle - the thickest layer (80 of the
  volume of the planet). It goes from solid to
  partially molten material called magma with
  depth.
• The Lithosphere (lithos solid) is made up of
  the crust and solid part of the upper mantle.
• The Asthenosphere (asthenos liquid) is a
  layer of partially melted, molten, rock that
  makes up the rest of the upper mantle just below
  the Lithosphere
• The lower mantle is mostly hot, liquid magma that
  extend down to the next layer
• It is the convection currents that occur in the
  Mantle that drive plate tectonics and continental
  drift.

5
Earths Interior

• The Core is at the center of the Earth and has
  two layers.
• The outer core is very hot, liquid metals mostly
  Iron (Fe) and Nickel (Ni)
• The inner core is also made of extremely hot
  metals but because of the tremendous pressure, it
  remains solid.
• it spins within the liquid, metal outer core and
  generates Earths magnetic field that protects
  our planet from dangerous radiation from space.

6

• Earths Layers

7
Plate Tectonics

• Plate Tectonics and Continental Drift Theories
  First started in the early 1900s by German
  scientist Alfred Wegener.
• He proposed that all of the continents originated
  from one large supercontinent (Pangaea) and that
  they drifted to their present locations over a
  long time.
• He based his theory on the following
  observations
• Continental margins (edges)
• Similar in shape and size
• Fit together like puzzle pieces

8
Plate Tectonics

• Rock types
• Rocks of Similar formation and age found on
  opposite continents

9
Plate Tectonics

• Fossils of the same animals and plants found in
  these rock layers, on different continents.
  (Mesosaurus)

10
Breakup of Pangaea
11
Exit Slip

• What are the three primary layers of earth?
  Describe each in detail.
• Where do convection currents occur?
• What is the difference between the theory of
  plate tectonics and continental drift?

12
Do Now

• What evidence was used to support the theory of
  plate tectonics? Describe in detail.
• Why wasnt Wegeners theory of continental drift
  widely accepted compared to the theory of plate
  tectonics?

13
Plate Tectonics

• More discoveries in the twentieth century tell us
  that Earths solid outer layer or crust
  (lithosphere) is broken into several large pieces
  called tectonic plates.
• Tectonic plates ride on top of the softer,
  putty-like upper mantle (asthenosphere).
• they are moved by upwelling due to convection
  currents in this soft, hot magma.

14
Plate Tectonics

• Tectonic plate boundaries occur at the margins
  (edges) of all these plates. There are three
  basic types of plate boundaries that form between
  two types of crust, continental and oceanic.

15
Plate Tectonics

• Divergent boundaries form where plates are
  pulling apart, away from each other
• Ocean to ocean Sea floor spreading, Mid-Atlantic
  ridge
• Continent to continent African Rift Valley

16
Plate Tectonics

• Convergent boundaries form where plates are
  crashing together
• Ocean to continent ocean crust subducts below
  the continental crust
• EX. West Coast of South America Andes Mtns.
• Ocean to ocean ocean crust subducts below
  another ocean crust.
• EX. Aleutian Islands/Indonesia/Japan
• Continent to continent 2 continental crusts
  collide.
• EX. The Himalayas/Rockies/Alps

17
Oceanic to Continental Convergence
18
Oceanic to Oceanic Convergence
19
Continental to Continental Convergence
20
Plate Tectonics

• Transform fault boundaries form where plates
  grind past each other
• Ocean to ocean Lateral faults along the
  Mid-Atlantic Ridge
• Continent to continent The San Andreas Fault
  (our backyard)
• The entire landscape of our planet has been
  shaped by a combination of all these processes

21
Transform Fault Boundary
22
Exit Slip

• Compare and contrast transform plate boundaries,
  convergent plate boundaries, and divergent plate
  boundaries.
• What boundaries occur where oceanic and
  continental crust collide?
• What boundaries occur where oceanic and oceanic
  crust collide?
• What boundaries occur where continental crust
  collides with continental crust

23
Do Now

• What type of plate boundary would I expect an
  island to form at? What are the two types of
  crust involved?
• What type of plate boundary would I expect a
  mountain to form at? What are the two types of
  crust involved?
• What type of plate boundary would I expect a
  trench to form at? What are the two types of
  crust involved?

24
Earthquakes and Volcanoes

• 17-2

25
Earthquakes

• Earthquake a sudden trembling of the Earth
  caused by a release of accumulated energy in the
  Lithosphere.
• Most occur at tectonic plate boundaries
• The point of rupture where the earthquake starts
  underground is the focus.
• The place on the surface directly above the focus
  is the epicenter.

26
Earthquakes
27
Earthquakes
28
Earthquakes

• Seismic Waves 3 types
• P-waves (Primary waves)
• Compressional/Longitudinal waves that travel
  through Earths interior very fast
• they bend as they pass through the liquid outer
  core.
• S-waves (Secondary waves)
• Transverse waves that travel through Earths
  interior slightly slower that P-waves, and DO NOT
  travel through liquid

29
Earthquakes
30
Earthquakes

• Surface Waves
• Slowest of the seismic waves and travel only at
  the surface. The most destructive of the three
  waves

31
Earthquakes
32
Earthquakes

• Seismic waves are recorded on a seismograph.

33
(No Transcript)
34
Earthquakes

• The amplitude of seismic waves is measured by the
  Richter Scale.

35
Earthquakes

• Damage or Intensity from an earthquake is
  measured in the Mercalli Scale.

36
Earthquakes
Will The Big One Happen Here?
37
(No Transcript)
38
Exit Slip

• Describe the three types of waves involved in an
  earthquake? Describe the motion and damage of
  each.
• What is the difference between a focus and the
  epicenter?
• What are earthquakes measured on?

39
Do Now

• Describe the three types of waves involved in an
  earthquake? Describe the motion and damage of
  each.
• What is the difference between a focus and the
  epicenter?
• What are earthquakes measured on?
• What is the difference between the Richter scale
  and the Mercalli scale?
• Why are both scales necessary to use?
• Is a seismograph the same as the Richter scale?
  Why or Why not?

40
Volcanoes

• Volcanoes mountains formed through repeated
  eruptions of lava and pyroclastics.
• There are 4 main types of volcanoes.
• Shield Volcanoes
• Very large and spread out
• Gentle Slopes and Gentle Eruptions
• made from layers of lava
• Example Hawaii

41
Volcanoes
The Big Island of Hawaii
42
Volcanoes

• Composite or Strato Volcanoes
• Very large and tall
• Steep Slopes and Violent Eruptions because the
  lava is thick, viscous and gaseous
• made of alternating layers of lava and
  pyroclastics (cinders)
• Examples Mt. St. Helens, Mt. Shasta, Mt. Fuji,
  Mt. Vesuvius

43
Mt. Shasta
44
Mt. St. Helens before and after
45
(No Transcript)
46
Volcanoes

• Cinder Cones
• small not very tall
• moderate slopes and mild eruptions
• made of pyroclastics (cinders and ash)
• Examples Pisgah Crater, Paricutín Mexico

47
Cinder Cone
48
Size Comparison

• Magma molten rocks from the mantlecrust
• Lava magma that has reached the surface

49
Volcanoes
Calderas
a. Calderas - large depressions in volcanoes.
b. Nearly circular
c. Formed when volcano collapses inward
after a catastrophic explosion
d. Size exceeds one mile in diameter e. Examples
Crater Lake , Yellowstone, Long Valley
50
Exit Slip

• What are the three different types volcanoes?
• Describe each type of volcano
• Provide one example of each type of volcano and
  describe why that example fits the type.

51
Do Now

• What is a caldera? Provide one example
• What is a cinder cone volcano? What is one
  example?
• What is a shield volcano? Provide one example.
• List each type of volcano from least explosive to
  most explosive

52
Minerals and Rocks

• 17-3

53
Minerals

• Minerals - the materials that make up rocks. A.
  There are about 3500 different minerals found in
  the Earths crust and only 20 of these make up
  95 of all rocks.

54
Minerals

• All minerals share the following
  characteristics
• Naturally occurring, inorganic materials
• Definite chemical composition (chemical formula).
• Solids with a specific crystalline structure
• .

55
Minerals

• There are nine common rock-forming
  minerals/mineral groups. Nearly all of these are
  silicates, meaning they consist of metal atoms
  combined with silicon and oxygen

56
Minerals

• Nine most common rock-forming minerals or mineral
  groups
• Quartz (Silica) silicon dioxide, SiO2
• Feldspars sodium or calcium aluminum silicates,
  NaAlSiO8 or CaAlSiO8
• Amphiboles Complex hydrous silicates, (OH)
  containing calcium, magnesium, and iron
• Pyroxenes Closely related to the Amphiboles

57
Minerals

• Micas Sheets of soft silicates with potassium
  (K), calcium (Ca 2 ), or sodium (Na) ions
  between the layers
• Chlorites magnesium, iron-aluminum silicates
  Mg6(AlSi3)O10 or Fe6(AlSi3)O10
• Calcite Most common of the carbonate
  minerals, CaCO3
• Dolomite Both a rock and mineral, MgCa(CO3)2
• Olivine A magnesium or iron silicate colored
  various shades of green, Mg2SiO4, Fe2SiO4

58
Rocks

• A Rocks characteristics and appearance reflect
  its mineral composition and the way it was
  formed.
• Rock can form in three different ways.
• Igneous rocks (formed by fire) formed when
  liquid magma solidifies.
• Two types
• Extrusive (Volcanic) forms when magma erupts
  (lava) and solidifies quickly at the surface.

59
Rocks

• EXAMPLES basalt, tuff, obsidian,
  pumice,
• rhyolite, andesite

60
Rocks

• Intrusive (Plutonic) form when large bubbles
  of magma are trapped beneath the surface of the
  Earth (pluton) cools and solidifies slowly under
  pressure forming crystals.
• EXAMPLES granite, gabbro, diorite.

61
Rocks

• Half Dome a pluton above ground

62
Rocks

• Sedimentary rocks Form when sediments, or small
  pieces of weathered rock (clay, mud, sand,
  gravel, etc.) are deposited, compressed, and
  cemented together to form solid rock.
• The remains of living organisms can also be
  deposited along with these sediments forming
  fossils within the layers of these rocks.
• The type of sedimentary rock created depends on
  the sediments that formed it, and is named
  according to fragment size.
• EXAMPLES mudstone, sandstone, limestone, coal,
  conglomerate

63
Sedimentary Rocks
64
Rocks

• Metamorphic rock (to change in form) Forms when
  older igneous, sedimentary, or other metamorphic
  rocks are changed due to extreme heat and/or
  pressure.
• Heat and pressure occurs in subduction zones
• Heat occurs in volcanic vents contact
  metamorphism
  Pressure occurs at convergent plate boundaries
  forms fold mountains

65
Rocks

• The Rock Cycle the model that shows the origin
  of the 3 rock types and their interrelatedness to
  each other
• The absolute age of a rock is determined by
  radioactive isotopes
• The Principle of Superposition is used to date
  rocks relatively

66
Exit Slip

• What are the different types of rocks?
• Describe each rock type in detail.
• What is the difference between igneous intrusive
  and igneous extrusive rock?
• What characteristic do all minerals share?
• How many different types of minerals exist?
• How many minerals make up most of Earths rocks?
• list the nine most common rock forming mineral
  groups.

67
Do Now

• Describe the rock cycle in detail

68
Weathering, Erosion, and Deposition

• 17-4

69
Weathering, Erosion, and Deposition

• VI. Weathering - a change in the physical form or
  chemical composition of rock materials exposed at
  the Earths surface.
• A. Physical weathering - breaks rocks down into
  
• smaller and smaller pieces and does not
  change the chemical composition. This occurs by
  the
• following processes.
• 1. Water erosion
• 2. Frost wedging
• 3. Wind abrasion
• 4. Organic activities
• 5. Other physical forces

70
Weathering, Erosion, and Deposition

• Chemical weathering - when minerals in rocks
  react chemically to break down and change their
  chemical form.
• Some minerals dissolve easily in water. Rain
  water is slightly acidic (pH 5.7) due to a
  natural reaction between water vapor H2O, and
  Carbon Dioxide CO2 , in the atmosphere. This
  forms a weak acid solution H2CO3 .

71
Weathering, Erosion, and Deposition

• EXAMPLE The formation of Limestone caverns or
  sink holes. (See figure 17-29, pg.584).
• Acid rain - a severe form of this process caused
  by man-made pollutants.
• Polluting gasses emitted during the burning of
  fossil fuels (gasoline, coal, oil,) mix with
  water vapor in the atmosphere to form acid rain.
• These acids have a stronger pH than normal rain
  water and do a lot of damage to man-made and
  natural stone structures. (See figure 17-30, pg.
  585).

72
Weathering, Erosion, and Deposition

• Erosion - the removal of weathered rock materials
  (sediments) and minerals by one or more of the
  following processes
• Moving water (most effective)
• Rivers or streams
• Ocean currents, waves or tides
• Winds
• Sand or dust storms
• Ice
• Glaciers massive, long lasting accumulations of
  compacted snow and ice that moves down slope
  slowly
• Frost Wedging
• Gravity
• Land, rock, or mud slides

73
Weathering, Erosion, and Deposition

• Deposition - when the force in these moving
  processes slows or stops and the sediments are
  deposited (laid down) forming many different
  land forms
• Deltas and flats
• Beaches and sand bars
• Sand dunes and hills
• Moraines
• Alluvial fans, rock piles and valleys

74
Exit Slip

• What is the difference between erosion,
  deposition, and weathering.
• Provide one example for each of the above.