Plate Tectonics

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Plate Tectonics
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Sources of Earths energy

• Internal- radioactive decay.
• External- The Sun.

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Producers

• Organisms that use sunlight energy to make sugars.

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Photosynthesis

• Plants and certain microorganisms, such as algae,
  make their own food.

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• We get our energy by eating plants or
  plant-eating animals.
• We are heterotrophs.

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Earth is divided into three layers

• The crust.
• The mantle.
• The core.

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Lithosphere

• The crust and rigid upper part of the mantle.
• It is divided into tectonic plates.

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Tectonic Plates

• Pieces of lithosphere that float on a denser,
  molten layer of Earth, known as the asthenosphere.

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Asthenosphere

• Soft layer of the mantle made up of semi-solid
  rock that flows slowly.

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Plate Tectonics Theory

• Theory that Earths lithosphere is divided into
  tectonic plates that can move around on top of
  the asthenosphere.

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Types of Plates

• Continental plates.
• Oceanic plates.

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Diverging boundaries

• When two tectonic plates move away from each
  other.
• They form deep valleys called rift valleys.

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• When magma rises through the gaps between the
  plates, it cools, creating a ridge (new crust).
  This is called sea-floor spreading.

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Mid-Ocean Ridges

• Long underwater mountain chains along divergent
  boundaries.

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Converging boundaries

• When two tectonic plates push into one another.

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• If the two convergent plates are oceanic, one is
  subducted, or pushed under the other.
• Volcanoes form.
• Hawaiin islands formed this way.

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• When a continental plate collides with an oceanic
  plate, the oceanic plate slides under the
  continental plate, forming volcanoes.

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• When two continental plates collide, mountains
  form, such as the Himalayas.

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Transform Boundaries

• When two tectonic plates slide past each other.
• This causes earthquakes.

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Wind

• Moving air.
• Air moves from areas of high pressure to areas of
  low pressure.

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Offshore Breeze

• When air over the land moves out toward the sea.
• At the beach in the morning air over land is
  cooler with high pressure.

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Sea Breeze

• Later in the day, the sun warms the land, air
  over land becomes less dense and pressure drops.
  Cooler air rushes from the sea.

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Surface Currents

• A shallow ocean current.
• They are produced by the wind.

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Reservoirs

• Areas where various elements are stored for
  periods of time and from which they are recycled.

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Climate

• The average weather of a region over a long
  period of time.
• Climate of northern Europe is cool and damp.

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What determines climate?

• Latitude.
• Prevailing winds.
• Elevation.
• Mountains.
• Water bodies.

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Weather

• Short lived atmospheric phenomena, such as
  thunderstorms and blizzards.

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Rain Shadow

• An area of decreased rainfall on the leeward side
  of a mountain.

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The Law of Superposition

• Layers of older rocks lie under layers of younger
  rocks.

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Fossil

• The remains of a living thing.
• Fossils can be used to find the relative age of a
  rock.

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Radioactive Dating

• A technique that involves comparing the amount of
  a radioactive and non radioactive forms of an
  element in a rock or fossil.

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• Radioactive dating tells us the actual age of a
  rock or fossil.

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Half-Life

• The amount of time for half the substance to
  decay into a nonradioactive form.

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• Earth was formed 4.6 billion years ago.
• Living things appeared 3.5 billion years ago.

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Nebular Cloud

• An interstellar haze of particles.
• Gravity drew particles together to form the Sun,
  planets, and moons.

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The Big Bang Theory

• An explosion that produced all the matter and
  energy of the universe.
• Occurred about 13.7 billion years ago.

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Galaxies

• Families of billions of stars.
• Ewe live in the Milky Way Galaxy.

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• Evidence that the universe is expanding comes
  from observing the light emitted by stars.

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The Red Shift

• When an object is moving away, the light it
  reflects seems to have wavelengths shifted toward
  the red end of the spectrum.

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• The red shift indicates that the universe is
  expanding!

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• Star Development

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The life cycle of stars

• Nuclear fusion? red giant? white dwarf.
• In more massive stars nuclear fusion?
  supergiants? supernova? neutron or black hole.

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Protostar

• When a nebula (cloud of gas and dust) contracts
  and shrinks, forming a sphere of matter.
• A beginning star!

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Red Giant

• A large, reddish star in late in its life cycle
  that fuses helium into carbon or oxygen.

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Black hole

• An object so massive and dense that not even the
  light can escape its gravity.

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Neutron star

• A dead star with the density of atomic nuclei.

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White dwarf

• A small, very dense star that remains after
  fusion in a red giant stops.

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• Very large stars become supergiants. Supergiants
  create elements as heavy as iron. This stops
  fusion, and explodes into a supernova, and the
  massive star dies.

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• If the mass of the dead star is 1.4 to 3 times
  that of the sun, it can become a neutron star.
• If the mass is more than 3 times that of the sun,
  it becomes a black hole.