Geography

• Earthquake


  A sudden movement or trembling of Earth's crust
• Earthquakes occur


  1. Plates collide or slide past one another

  2. Pressure builds up

  3. One of the plates slips

  4. Pressure is eased

  5. A huge amount of energy is suddenly released
• Earthquake


  • Plates suddenly move along the fault line
  • The focus is the point deep underground where the earthquake occurs
  • Shock waves or tremors spread out from the focus, causing Earth's surface to shake (or quake) for a period
  • The tremors are usually strongest at the epicentre, the area on the surface directly above the focus
• Most tremors last from a few seconds to up to a minute
• Seismograph


  • Instrument that detects and measures tremors from an earthquake
  • Pen on the tip of the seismometer records the tremors on a rotating drum to produce a seismogram
• The seismograph can detect tremors too small for a person to be aware of
• Tsunami


  A huge wave or series of waves, can be as high as 60 metres, usually a result of an underwater earthquake or volcanic eruption
• How a tsunami is formed

  1. Ocean floor at a plate boundary rises or falls suddenly

  2. Displaces the water above it

  3. Starts the rolling waves that grow to become a tsunami
• Rock is the hardest material that forms earth's crust.
• All rocks are solid, occur naturally, and are made up of one or more minerals that have been compressed and cemented together.
• Rocks differ from eachother in their:

  Mineral content

  Colour

  Hardness

  Texture
• 3 types of rocks:

  Igneous

  Sedimentary

  Metamorphic
• Igneous rocks


  Rocks formed as a result of volcanic activity
• Formation of igneous rocks

  1. Volcanic material cools down and solidifies

  2. Material that cooled inside the crust forms intrusive rocks

  3. Material that cooled on the surface forms extrusive rocks
• Sedimentary rocks are formed from remains of other rocks, plant life, and animal life.
• Remains are compressed and cemented together to make sedimentary rocks.
• Rocks that allow water to pass through it are called permeable.
• Limestone is the most common rock in Ireland
• Metamorphic rocks are formed when existing igneous or sedimentary rocks come into contact with great heat and pressure.
• Volcanic activity takes place along the boundaries of plates.
• Volcanic activity results in mid-ocean ridges or volcanic cones.
• A mid ocean ridge is an underwater mountain range formed when two plates separate.

  
• Geothermal energy is made by hot water or steam
• Volcanic mountains are formed when molten magma erupts through a hole in the crust called a vent.

  
• Magma is called lava once it's over the surface
• Erosion: wearing away material from the surface
• Transportation: removing material the river has eroded.
• Deposition: dropping material the river was transporting
• Hydraulic action: force of water breaking off material from banks and beds of river.
• Attrition: material is worn down, smoother, and rounded by stones bouncing off eachother.
• Solution: acids in the water dissolve some rocks
• Rivers deposit their load when they lose energy, speed, volume decreases, or it flows into a lake or sea
• Meander: curve in a river
• Oxbow lake: when the river gets too close and ends up cutting off the river channel making a U shaped lake.

  
• Features of a river

  • Source
  • Course
  • Tributary
  • Confluence
  • Mouth
  • Estuary
  • Drainage basin
  • Watershed
• Source


  The point where a river begins
• Course


  The route taken by a river as it flows into the sea
• Tributary


  A small river or stream that joins a larger one
• Confluence


  The place where two rivers meet
• Mouth


  The place where a river enters the sea