Science 4th quarterly

• Crust


  Earth's outermost layer
• Oceanic crust


  • Relatively thin compared to the crust below the continents
• Continental crust


  • Made up of lighter, less dense granite rocks
• Mantle


  A layer of rock materials between the crust and the core
• Mohorovicic discontinuity or Moho


  Marks the boundary between the crust and the mantle
• Discontinuity


  The interphase of two layers, marked by the sudden change of density of the rock layers
• Core


  Located at the Earth's center
• Layers of the core


  • Inner core
  • Outer core
• Inner core


  • Believed to be made up of solid iron, responsible for Earth's magnetic field
• Outer core


  • Thought to be composed of liquid iron-nickel alloy due to extremely high temperature
• The deepest hole drilled only went 13km deep
• Continental Drift Theory


  Theory by Alfred Wegener that the world's continents were once part of a single landmass called Pangaea
• Pangaea likely began to split around 200 million years ago, and have continued to move to where they are now
• Plate Tectonic Theory


  Earth's solid, brittle lithosphere is broken into several tectonic plates that glide over the partially molten asthenosphere
• Boundary


  The place where two plates meet
• Types of plate boundaries

  • Divergent
  • Transform
  • Subduction or Convergent
• Divergent Boundary


  Formed between two plates that are moving away from each other
• Transform Boundary


  Also called conservative plate boundaries, formed between two plates that are moving horizontally past each other
• The San Andreas is the most popular transform boundary
• Convergent Boundary


  Formed where two plates converge
• Earthquake


  The shaking of the ground due to the sudden movement of Earth's lithospheric plates
• Types of earthquakes


  • Tectonic earthquake
  • Volcanic earthquake
• Focus


  The point underneath the epicenter where the displacement of rocks originated
• Epicenter


  The point on the surface of Earth directly above where the displacement of rocks originated
• Fault


  Zones of fracture where large blocks of rocks move relative to each other
• Types of faults


  • Normal fault
  • Strike-slip fault
  • Reverse fault
• Main earthquake zones


  • Circum-Pacific Belt
  • Alpide Belt
  • Mid-Atlantic Ridge
• Circum-Pacific Belt


  Also called the Ring of Fire due to the large number of active volcanoes
• Alpide Belt


  Extends from Java to Sumatra, through the Himalayas, the Middle East, the Mediterranean, and out into the Atlantic
• Mid-Atlantic Ridge


  Consists mostly of an underwater mountain range
• Intensity of an earthquake


  Measure of the damage incurred on the surface and its perceived effects
• Richter Scale


  Measures the magnitude of earthquakes
• Instruments used to detect earthquakes


  • Seismograph
  • Laser rangefinder
  • Geiger counter
  • Extensometer
• An earthquake can cause excessive damage to properties in towns and cities, including building and structure collapse, cracks and gaps in the ground, landslides, and tsunamis
• What to do before, during, and after an earthquake

  1. Before: Prepare emergency plans and supplies

  2. During: Stay calm, take cover, avoid falling objects, move to higher ground if near water

  3. After: Check for damage, assist others, make repairs
• Magma


  The molten rock that collects in compartments also known as magma chambers
• Caldera


  When volcanoes deplete the magma within their chambers, the volcano may collapse on itself, creating a large, basin-shaped volcanic opening
• Parts of a volcano

  • Vent
  • Pipe
  • Crater
  • Cone
• Signs of impending volcanic eruption

  • Bulging sides
  • Earthquakes
  • Gaseous fumes
• Types of volcanic eruptions

  • Effusive eruption
  • Explosive eruption