The Restless Earth

A mindmap of the information in the Restless Earth topic. (See other mindmap for Case Studies)

HideShow resource information
View mindmap
  • AQA GCSE Geography: The Restless Earth
    • 2. Plate Margins
      • Destructive
        • Earthquakes Happen
        • Composite Volcanoes occur
        • When two plates move towards each other
          • If the plates are continental and oceanic, then the oceanic plates subducts underneath.
          • If they are both continental, the plates are pushed upwards forming fold mountains
        • Example: The Andes and Peru-Chile deep-sea trench in South America. There is the Nazca plate and the South American Plate
      • Constructive
        • Shield Volcanoes occur
        • Earthquakes Happen
        • When two plates move away from each other
        • Example: The Mid- Atlantic ridge in the Atlantic Ocean. There is the Eurasian Plate and North American Plate
      • Conservative
        • No Volcanoes
        • Earthquakes Happen
        • Example: San Andreas Fault in California. There is the Pacific Plate and North American Plate
        • Two plates move past each other
    • 3. Landforms at Plate Margins
      • Fold Mountains
        • Example: The Andes in South America
        • Formed at Destructive Plate margins when both plates are Continental
      • Ocean Trenches
        • Formed at Destructive Plate Margins where Oceanic and Continental Plates meet
        • Formed in subduction zones. This is where the oceanic plate subducts beneath the continental plate, and this creates a large trench.
        • Example: The Peru-Chile deep-sea Ocean Trench in South America
      • Volcanoes
        • Composite
          • Found at Destructive Plate Margins
          • Features
            • Steep Sides and narrow base
            • Made up of alternate layers of ash and larva
            • Erupts rarely but violently- expelling steam, ash, larva and rock
            • Sticky larva that doesn't flow very far. It's also acidic.
          • Example: Mount Mayon in the Philippenes
        • Shield
          • Example: Mauna Loa in Hawaii
          • Found at Constructive Plate Margins
          • Features
            • Wide Base and gently sloping sides
            • Runny larva that flows a long way. it is also basic
            • Frequent eruptions that aren't violent
    • 1. The Earth's Structure
      • Convection Currents
        • Caused by heat rising from the Earth's core, which makes the magma move
        • The magma moving causes the plates to move
      • Structure
        • Core
          • Inner Core
            • Centre of the Earth
            • Solid
            • Very hot, about 5500 degrees Celsius
          • Outer Core
            • Liquid iron and Nickel
        • Mantle
          • Soft Molten rock
          • About 3800 degrees Celsius
        • Crust
          • Thin, hard outer shell of the Earth
          • Broken up into large pieces called Tectonic Plates
      • Types of crust
        • Oceanic
          • 5-10km thick
          • Dense
          • Sinks when meets continental crust
          • Oldest is only 180 million years old.
          • What you get under oceans
        • Continental
          • 25-100km thick
          • Less Dense
          • Doesn't Sink
          • Very old; 3- 4 billion years old
          • What you get under land masses
    • 4.Super Volcanoes
      • Features of eruption
        • Ash shoots kilometers into the air
          • Blocks out daylight over nearly all the continents, leading to mini ice ages and famines as food cannot be grown
        • Ash settles over hundreds of Km2 burying field and buildings
        • At least 1000km3 of material emitted
          • Rock
          • Ash
          • Larva
        • A thick cloud of 'super-heated' gas and ash will flow at high speed from the volcano, destroying everything within 10 miles.
      • Formation
        • 1. Magma is blocked from reaching the Earth's Surface
        • 2. Pressure begins to build up, more rock melts so more magma is formed. This creates a large magma chamber
        • 3. When the pressure becomes to much, the entire surface above the chamber is blown away by a huge explosion. A caldera is formed.
      • Example: Yellowstone in the USA
      • Characteristics
        • Flat
        • Cover a large area
        • Have a caldera- a large depression in the ground
    • 5. Earthquakes
      • Measuring Earthquakes
        • Richter Scale
          • Measures energy released
          • Uses a seismometer
          • Scale
            • Unlimited
            • Logarthmic, meaning that each degree is ten times as powerful as the one before it
        • Mercalli scale
          • Measures visible and felt effects of an earthquake
          • Goes from 1 to 12, with 12 being total destruction
            • (Uses Roman Numerals)
      • Features
        • The Focus is the point at which the earthquake actually happens (beneath the ground)
          • The shallower the focus, the more damaging the earthquake on the surface
        • The Epicentre is the point on the surface above the focus
          • The closer to the epicentre, the worse the destruction
        • Shock waves radiate out in all directions from the focus.
      • Reasons for occurence
        • At Constructive Plate Margins, friction builds up as both plates move over the mantle
          • This friction is suddenly released when it becomes too strong, causing the plates to jerk past each other and shock waves to be emitted
            • At Destructive Plate Margins, friction mounts when plates push at each other or when one slides underneath the other.
            • At Conservative Plate Margins, friction mounts when the plates get stuck sliding past each other
        • At Conservative Plate Margins, friction mounts when the plates get stuck sliding past each other
        • At Destructive Plate Margins, friction mounts when plates push at each other or when one slides underneath the other.
    • 6. Tsunamis
      • Occur when an earthquake happens with an epicentre on the seabed.
        • This  results in lots of displaced water travelling in all directions, including towards land.
  • Shield Volcanoes occur
  • At least 1000km3 of material emitted
    • Rock
    • Ash
    • Larva

Comments

No comments have yet been made

Similar Geography resources:

See all Geography resources »See all Natural hazards resources »