EARTH SCIENCE

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EARTH SCIENCE

• California Science Standards

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Standard 3 Plate tectonics

• Plate tectonics operating over geologic time has
  changed the patterns of land, sea, and mountains
  on Earths surface
• a. features of the ocean floor (magnetic
  patterns, age, and sea-floor topography) provide
  evidence of plate tectonics
• b. structures that form at the three different
  kinds of plate boundaries.
• c. properties of rocks based on the physical and
  chemical conditions, in which they formed
• d. why and how earthquakes occur and the scales
  used to measure their intensity and magnitude.
• e. two kinds of volcanoes one kind with violent
  eruptions producing steep slopes and the other
  kind with voluminous lava flows producing gentle
  slopes.
• f. location and properties of volcanoes that are
  due to hot spots and the explanation for those
  that are due to subduction.

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Tectonic Forces Convection Currents
The internal heat engine of the Earth.

• Material in the mantle is heated by the
  radioactive core
• it floats to the surface next to the crust
• as it cools, it moves back down towards the core

7c Movement of matter among reservoirs is driven
by Earths internal and external sources of energy
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Tectonic Forces Convection Currents
This continual movement (called convection
currents) causes the crust to move in plate
tectonics.
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3a. Ocean Floor was formed by sea-floor
spreading(Magnetic patterns, age, and
sea-floor topography) provide evidence of plate
tectonics
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3a. Sea-Floor Spreading/magnetic reversals

• As magma rises and cools, iron and magnesium
  minerals align themselves to the Earths magnetic
  field
• Magnetic Stripes are formed
• The Earths magnetic field reverses polarity
• Magnetic stripes are mirrored on each side of the
  mid-ocean ridge

• Youngest rocks form at ridge
• Older rocks are further from ridge
• Oldest rocks are located at subduction zones

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3 different kinds of plate boundaries
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Divergent Boundaries

• Mid-oceanic ridges/rift valley created
• Magma enters fissures
• Lithosphere moves away from boundary
• New ocean crust is created

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Convergent Boundaries

• Subduction Zones are caused when ocean plates
  slide under each other or continental plates
• This subduction created magma at depth which
  moves upward, pushing up the land above it.
• This magma/lava solidifies into
  intrusive/extrusive igneous rock
• Heat from the magma can change the rock around
  it. Rock that recrystallizes without melting
  becomes metamorphic rock..

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Subduction Zones are formed at Convergent
Boundaries
Denser oceanic plates always subduct beneath less
dense continental plates
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Transform Boundaries

• Plates slip past each other
• San Andreas Fault is a famous transform boundary
• causes most earthquake damage

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3c. Properties of rocks

• Types of rocks - categorized by how formed
• IGNEOUS - melting cooling
• extrusive - cools quickly outside earth-small
  grained
• intrusive - cools slowly inside - large grained
• Sedimentary - compaction and cementing
• Metamorphic - heat pressure

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3d. How why of Earthquakes

• The movement of the plates of the lithosphere
  causes stress on the rocks of the Earth
• Friction usually holds the rocks together, the
  stress of plate movement can cause the rock to
  break.
• Waves move out in circles from the point of
  rupture (focus)

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Primary waves (P Waves)

• Also known as compressional or longitudinal waves

• They are the first waves to arrive at a location
  away from the focus.
• They travel through all states (liquid/solid)

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Secondary Waves

• Also known as transverse, shear or S waves
• They move perpendicular to the direction of
  motion
• They can only travel through solids

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Surface Waves

• There are two kinds of surface waves the first
  travels along the surface in an up-and-down
  rolling motion
• The second shakes the ground sidewise
• They usually cause most of the damage in an
  earthquake

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Magnitude

• Energy released is measured with Richter Scale
• With earthquakes over 5.5, the Richter magnitude
  is unreliable

• Measured by amplitude of the highest wave and
  the difference in arrival time between p and
  s-waves

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Intensity

• Energy absorbed is measured using the Modified
  Mercalli Intensity Scale.

• This scale measures the effects of an earthquake
  at a certain location
• Each location may give a different reading

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• 3f. Volcano formation - subduction

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• 3f. Volcano formation -
• can form from diverging plates, but ridge is more
  likely
• since plates are moving apart - new crust is
  forming

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• 3f. Volcano formation - hot spots

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• 3e. two kinds of volcanoes

one kind with violent eruptions producing steep
slopes
other kind with voluminous lava flows producing
gentle slopes
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3e. Shield Volcanoes

• Gentle slopes
• Erupts basaltic lava low in silica and high in
  iron and magnesium
• Not explosive

• Flood basalts, hot spots, spreading centers
• Hawaiian Islands, Modoc Plateau

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3e. Stratovolcanoes

• Steep sides
• Erupts andesite or rhyolite lava rich in silica
  and low in iron and magnesium
• Can be highly explosive, produces ash falls, slow
  moving lava flows, and pyroclastic clouds
• Mt. Lassen, Mt. St. Helens, Yellowstone

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Standard 7 Biogeochemical cycles

• Elements move within and throughout the Earth in
  biogeochemical cycles

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• 7ab carbon cycle

Notice the role of photosynthesis and respiration
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• 7a nitrogen cycle

Notice the role of decomposers bacteria
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ENERGY is stored different ways -

• The energy in coal (from solar radiation-the sun)
  is stored as chemical energy in rocks
• Plants store solar energy by a process called
  photosynthesis
• That energy is stored as chemical energy in
  organic (carbon based) molecules (oil and in
  plants)

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• 7c Movement of matter among reservoirs is driven
  by Earths internal and external sources of energy

• Heat from the core is transferred through the
  mantle to the lithosphere because it is less
  dense

• As the crust becomes older, it cools and
  increases in density until it subducts into the
  asthenosphere

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• 9b Natural Hazards of California

• Faulting - near plate boundaries (coast)
• Volcanoes - coastal mountains
• Landslides - coastal areas liquefaction
• Coastal erosion

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• 9C Importance of water to society,
• the origins of Californias fresh water and the
  relationship between supply and need

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9C the origins of Californias fresh water

• The Sierra Nevada and Klamath Mountains are the
  major source of Californias water
• Streams bring snow melt from the mountains in
  Northern California, where the population is
  small, to the rivers in the Great Central Valley
• Water in Southern California, with a very large
  population, is imported from Northern California
  by the California Aqueduct and from the Colorado
  River

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Water Quality

• Coastal areas have a problem with saltwater
  intrusion into fresh groundwater aquifers