Geography junior Cert

• The Earth's Layers


  • Crust
  • Mantle
  • Outer core
  • Inner core
• Plates


  • 7 major plates
  • Destructive plates (two colliding plates)
  • Constructive plates (two separating plates)
• Convectional currents


  1. The very hot core heats the magma

  2. Convectional currents are set up in the mantle

  3. Molten magma moves upwards from the core towards the crust

  4. At the crust, the magma cools and sinks back down towards the core so the cycle can start over again

  5. There is friction between the convectional currents and the plates

  6. The friction causes the plates to move slowly on top of the mantle
• Mid-ocean ridge


  Underwater mountain range formed where two plates separate
• Mid-ocean ridge formation


  1. As the plates move apart, molten magma rises from the mantle and fills the gap between the plates

  2. When the magma meets the cold seawater, it cools and solidifies to form a new ocean floor

  3. As the eruptions of magma continue in an endless cycle, the ocean floor is built up to form a long ridge of mountains
• The mid ocean ridge runs north to south for the full 16,000km length of the Atlantic Ocean
• The mid ocean ridge is so high in places that it's exposed above sea level e.g Iceland
• Volcanoes


  1. Magma from the magma reservoir reaches the surface through a vent which may erupt violently, blasting materials into the sky through the crater

  2. When magma reaches the surface, it's known as lava

  3. Lava pours out of the crater and flows down the side of the cone, cooling and hardening

  4. Other materials may also come out during the eruption

  5. Layers of these materials build up to form a cone shaped mountain
• Types of volcanoes


  • Active volcanoes still erupt on a regular basis e.g Mount Vesuvius
  • Dormant volcanoes erupted in the past but may not erupt again e.g Mount Cotopaxi
  • Extinct volcanoes have not erupted in historic times e.g Mount Slemish
• Advantages of volcanoes


  • Fertile soil
  • Precious stones and minerals can be originated in volcanoes
  • Building materials from rocks formed as a result of volcanic eruption (igneous rocks)
  • Hot springs and geysers can be used to generate electricity
  • Volcanoes attract tourists
• Disadvantages of volcanoes


  • Loss of life
  • Damage to property
  • Destroys wildlife and the environment
• Pacific Ring of Fire


  Active volcanoes that surround the Pacific Ocean
• Fold mountains


  • They are found along plate boundaries
  • When two plates collide, the rocks tend to buckle and crumple upwards into a series of folds
  • Large amounts of compression occurs
  • Armorican fold mountains are smaller in size because they are older and have been severely worn done
  • Alpine fold mountains are larger in size because they are younger and have not been as severely worn down
• Earthquake


  A sudden movement or trembling or the Earth's crust in the form of a series of shocks or tremors
• Earthquakes occur


  At boundaries where plates collide
• Focus


  The point deep in the Earth's crust where the earthquake begins
• Epicentre


  The point on the surface directly above the focus and this is the place where tremors are the strongest
• Effects of Earthquakes


  • Builds collapse, especially those that are closer to the epicentre
  • Roads begin to crack and railway lines start to bend
  • Fires may occur when gas pipes break
  • Tsunamis can result from underwater earthquakes
• Reducing Impact of Earthquakes

  • Build buildings that sway with minor earthquakes
  • Scientists should examine seismographs to predict potential earthquakes
• Richter Scale


  Measures and determines the strength of earthquakes
• The Earth's Layers


  • Crust
  • Mantle
  • Outer core
  • Inner core
• Plates


  • 7 major plates
  • Destructive plates (two colliding plates)
  • Constructive plates (two separating plates)
• Convectional currents


  1. The very hot core heats the magma

  2. Convectional currents are set up in the mantle

  3. Molten magma moves upwards from the core towards the crust

  4. At the crust, the magma cools and sinks back down towards the core so the cycle can start over again

  5. There is friction between the convectional currents and the plates

  6. The friction causes the plates to move slowly on top of the mantle
• Mid-ocean ridge


  Underwater mountain range formed where two plates separate
• Mid-ocean ridge formation


  1. As the plates move apart, molten magma rises from the mantle and fills the gap between the plates

  2. When the magma meets the cold seawater, it cools and solidifies to form a new ocean floor

  3. As the eruptions of magma continue in an endless cycle, the ocean floor is built up to form a long ridge of mountains
• The mid ocean ridge runs north to south for the full 16,000km length of the Atlantic Ocean
• The mid ocean ridge is so high in places that it's exposed above sea level e.g Iceland
• Volcanoes


  1. Magma from the magma reservoir reaches the surface through a vent which may erupt violently, blasting materials into the sky through the crater

  2. When magma reaches the surface, it's known as lava

  3. Lava pours out of the crater and flows down the side of the cone, cooling and hardening

  4. Other materials may also come out during the eruption

  5. Layers of these materials build up to form a cone shaped mountain
• Types of volcanoes


  • Active volcanoes still erupt on a regular basis e.g Mount Vesuvius
  • Dormant volcanoes erupted in the past but may not erupt again e.g Mount Cotopaxi
  • Extinct volcanoes have not erupted in historic times e.g Mount Slemish
• Advantages of volcanoes


  • Fertile soil
  • Precious stones and minerals can be originated in volcanoes
  • Building materials from rocks formed as a result of volcanic eruption (igneous rocks)
  • Hot springs and geysers can be used to generate electricity
  • Volcanoes attract tourists
• Disadvantages of volcanoes


  • Loss of life
  • Damage to property
  • Destroys wildlife and the environment
• Pacific Ring of Fire


  Active volcanoes that surround the Pacific Ocean
• Fold mountains


  • They are found along plate boundaries
  • When two plates collide, the rocks tend to buckle and crumple upwards into a series of folds
  • Large amounts of compression occurs
  • Armorican fold mountains are smaller in size because they are older and have been severely worn done
  • Alpine fold mountains are larger in size because they are younger and have not been as severely worn down
• Earthquake


  A sudden movement or trembling or the Earth's crust in the form of a series of shocks or tremors
• Earthquakes occur


  At boundaries where plates collide
• Focus


  The point deep in the Earth's crust where the earthquake begins
• Epicentre


  The point on the surface directly above the focus and this is the place where tremors are the strongest
• Effects of Earthquakes


  • Builds collapse, especially those that are closer to the epicentre
  • Roads begin to crack and railway lines start to bend
  • Fires may occur when gas pipes break
  • Tsunamis can result from underwater earthquakes
• Reducing Impact of Earthquakes

  • Build buildings that sway with minor earthquakes
  • Scientists should examine seismographs to predict potential earthquakes
• Richter Scale


  Measures and determines the strength of earthquakes