Physical Geography Paper 1

• System


  Set of interrelated components working together towards some kind of process
• Dynamic equilibrium


  Input and output are balanced
• Types of systems


  • Open system
  • Closed system
  • Isolated system
• Example of a closed system

  • The carbon cycle
• Global water distribution


  • Ocean 96.5%
  • Saline 0.4%
  • Fresh water 2.5%
• Freshwater distribution


  • Glacier and ice caps 68.7%
  • Ground water 30.1%
  • Fresh water 1.2%
• Surface water distribution


  • Ground, ice and permafrost 69%
  • Lakes 20.9%
  • Soil moisture 3.8%
  • Swamps 2.6%
  • River 0.49%
  • Living things 0.26%
• Positive feedback (PF)


  Systems responds by increasing the effects of the change, making the systems even further
• Negative feedback (NF)


  Systems responds by decreasing the effect of the change, keeping the system closer to the previous state
• Water cycle


  1. Evaporation

  2. Condensation

  3. Advection

  4. Precipitation

  5. Evapotranspiration

  6. Stored water

  7. Flow
• Hydrograph


  Shows how river discharges changes over time at a particular point in a river
• Increased runoff


  Reduced lag time and greater discharge, producing a steep hydrograph
• Main carbon stores


  • Marine Sediments and Sedimentary Rocks
  • Oceans
  • Fossil Fuel Deposits
  • Soil Organic Matter
  • Atmosphere
  • Terrestrial Plants
• Carbon sink


  More carbon in, less carbon out
• Carbon store


  Less carbon in, more carbon out
• Carbon sequestration


  The process of carbon being stored for a prolonged period of time in a carbon store
• Forests absorb CO2, convert it to organic matter, and store it in branches, trunks, roots, and surrounding soil
• Oceanic phytoplankton contribute significantly to natural carbon sequestration, absorbing large amounts of CO2 through photosynthesis
• Destructive plate boundary


  Plates get subducted by convection currents creating deep sea trenches, island arcs and fold mountains
• Constructive plate boundary


  Plates push apart against each other and magma rises up from the mantle forming a new crust
• Conservative plate boundary


  The tectonic plate boundaries slide across each other and this causes friction to occur
• Plate boundary discontinuities


  • Taylor Gutenberg discontinuity
  • Lehmann discontinuity
  • Mohorovicic discontinuity
• Sea floor spreading


  Tectonics plates split apart from one another at mid ocean ridges forming new landforms
• Slab pull


  Plates being destroyed at subduction zones pulls the plate along behind it
• Why plates move


  They move due to convection currents in the underlying asthenosphere
• Hot spots


  Area of persistent volcanic activity often within a plate, magma rises through a plume in the mantle
• Types of magma


  • Rhyolitic
  • Basaltic
  • Andesitic
• Eruption


  When pressure on a magma chamber forces magma up through a conduit end out a volcano vent
• Factors affecting eruption


  • Amount of gas
  • Silica content
  • Temperature
• VEI


  Volcanic explosivity index
• Types of volcanic eruptions


  • Plinian
  • Hawaiian
  • Strombolian
• secondary volcanic impacts

  • Climate change
  • Volcanic gas
  • Lahars
  • Acid rain
  • Flooding
• Secondary volcanic impacts

  • Climate change
  • Lahars
  • Acid rain
  • Flooding
  • Tsunamis/Earthquakes
• Tephra


  Solid material with volcanic bombs
• Volcanic prediction methods


  • Looking at previous volcanic history
  • Ground material
  • Gas collection
  • Ground water levels
• Volcanic protection methods


  • Prior warnings
  • Channels to divert lava
  • Alert systems
  • Shelter and aid
• Mount St. Helens is one of the five volcanoes in the Cascade Range in Washington State, USA
• Mount St. Helens eruption was caused by the oceanic crust (Juan de Fuca) plate subducting under the continental crust (North American plate)
• In March 1980 there were signs of an impending eruption at Mount St. Helens, as first earthquakes occurred and then steam filled with ash exploded onto the white glacial summit of the mountain
• The eruption of Mount St. Helens happened at 8:32am on 18th May