Geology and Nonrenewable Mineral Resources

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Chapter 16

• Geology and Nonrenewable Mineral Resources

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What is the Earths Structure?

• Core Earths innermost zone very hot solid
  inner part surrounded by a liquid core
• Mantle surrounds the core mostly solid rock
  outermost part is very hot, partly melted rock
  (like flowing plastic)
• Crust outermost and thinnest zone consists of
  the continental crust (underlies continents) and
  the oceanic crust (underlines oceans)

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35 km (21 mi.) avg., 1,200C
Crust
100 km (60 mi.) 200 km (120 mi.)
Low-velocity zone
Mantle
Solid
10 to 65km
2,900km (1,800 mi.) 3,700C
100 km
Outer core (liquid)
200 km
Core
5,200 km (3,100 mi.), 4,300C
Inner core (solid)
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Earths Crust and Mantle
Abyssal floor
Oceanic ridge
Trench
Abyssal floor
Volcanoes
Continental slope
Continental shelf
Abyssal plain
Oceanic crust (lithosphere)
Abyssal plain
Continental crust (lithosphere)
Mantle (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
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Movement of Heat within the Earth

• Internal Processes originate from the Earths
  interior
• Decay of radioactive elements in the crust adds
  to heat within the mantle
• Two types of heat movement happen inside the
  mantle
• Convection Cells large volumes of heated rock
  move (like pot of boiling water)
• Mantle Plumes mantle rock flows upward in a
  column (like smoke from a chimney)

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What are Tectonic Plates?

• Convection cells and mantle plumes both move
  upward as heated material is displaced by cooler,
  sinking material
• These flows of energy cause movement of tectonic
  plates
• Plates are about 60 miles thick
• Composed of continental and oceanic crust, and
  the outermost part of the mantle

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Spreading center
Oceanic tectonic plate
Oceanic tectonic plate
Ocean trench
Collision between two continents
Plate movement
Plate movement
Tectonic plate
Oceanic crust
Continental crust
Continental crust
Material cools as it reaches the outer mantle
Cold dense material falls back through mantle
Hot material rising through the mantle
Mantle
Two plates move towards each other.
Hot outer core
Inner core
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More about Plate Tectonics

• Tectonic plates move constantly, like large
  pieces of ice on lake surface
• Move about the rate of fingernails growing
• Widely accepted theory in the 60s.
• Throughout history, continents have drifted apart
  and joined together as plates move back and forth
  across Earths surface

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More about Plate Tectonics

• Produces mountain and ocean ridges
• Volcanoes and earthquakes are found at plate
  boundaries
• Allows us to trace how species migrated from one
  area to another

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Earthquake and Volcano Sites
Volcanoes
Earthquakes
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Boundaries Between Earths Plates

• Divergent Plate Boundaries plates move in
  opposite directions
• Convergent Plate Boundaries plates are pushed
  together by internal forces forms a trench
• Transform Faults occur where plates slide past
  one another most are on the ocean floor

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Between Earths Plates

• External Processes geological changes based on
  energy from the sun or gravity
• Erosion material is dissolved, loosened, or worn
  away from one part of the Earths surface and
  THEN deposited in other places
• Wind can cause erosion as soil is blown from one
  area to another
• Human activities accelerate erosion

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Continued

• Weathering process that loosens material that
  can be eroded
• Two Types of Weathering
• Mechanical Weathering large rock mass is broken
  into smaller fragments Frost Wedging (water
  collects in pores of rocks, expands, and splits
  rock)
• Chemical Weathering chemical reactions decompose
  a mass of rock

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Lake
Tidal flat
Glacier
Spits
Shallow marine environment
Stream
Barrier islands
Lagoon
Dunes
Delta
Dunes
Beach
Shallow marine environment
Volcanic island
Continental shelf
Coral reef
Continental slope
Abyssal plain
Continental rise
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Minerals and Rocks

• Earths crust is composed of minerals and rocks
• Mineral element or inorganic compound that
  occurs naturally and is solid (gold, silver,
  salt, quartz)
• Rock any material that makes up a large,
  natural, continuous part of the Earths crust
  most rocks consists of two or more minerals

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Three Major Types of Rocks

1. Igneous Rock formed below or on Earths surface
   when magma (molten rock) wells up, cools, and
   hardens into rock (granite, lava rock)
2. Sedimentary Rock formed from sediment when rocks
   are eroded, transported to another place, and
   deposited in water (sandstone)
3. Metamorphic Rock rock is subjected to high
   temperature, high pressure, or chemically active
   fluids (coal, slate, marble)

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Rock Cycle

• Rocks are constantly exposed to changing
  conditions
• Interaction of processes that change rocks from
  one type to another is called the Rock Cycle
• Slowest of all Earths cycles recycles material
  over millions of years

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Sedimentary Rock sandstone, limestone
Deposition
Transportation
Erosion
ROCK CYCLE
Heat, pressure, stress
Weathering
EXTERNAL PROCESSES
INTERNAL PROCESSES
Igneous Rock Granite, pumice, basalt
Metamorphic Rock Slate, marble,
Heat, pressure
Cooling
Melting
Magma (molten rock)
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Earthquakes

• Stress in the Earths crust can cause solid rock
  to deform until it fractures and shifts along the
  fracture (fault)
• Abrupt movement of an existing fault causes an
  earthquake
• When fracture happens, energy is released as
  shock waves

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Measuring Earthquakes

• Magnitude severity of an earthquake
• Measure amount of energy released in an
  earthquake
• Categories insignificant, minor, damaging,
  destructive, major, great
• Each level is 10x greater than the previous

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How Can We Reduce Earthquake Hazards?

• Examine historical records and make measurements
  to locate active fault zones
• Make maps to show high-risk areas
• Establish building codes for high-risk areas
• Try to predict where and when earthquakes will
  occur

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Volcanoes

• Occurs where magma (molten rock) reaches the
  Earths surface through a crack
• Volcanic activity can release debris (hot lava
  rock or ash), liquid lava, gases
• These gases may become concentrated in the
  atmosphere and become concentrated into sulfuric
  acid

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Volcano
extinct volcanoes
central vent
magma reservoir
lithosphere
Upwelling magma
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Aftermath of Volcanoes

• Between 1985 and 1999 561,000 people died from
  natural disasters about 30 of these were from
  earthquakes and volcanic eruptions
• Benefits scenery, lakes (Crater Lake in Oregon),
  fertile soil from weathering lava

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How Can We Reduce Volcano Hazards?

• Land-use planning
• Better prediction of volcanic eruptions
• Evacuation plans