Physical Geography

Physical Geography

1. The Earth's Crust

   • Plates
     • Oceanic Plate
       • made of Basalt
       • are between 5Km and 10Km thick
       • 'Floats on a very hot mantle
     • Continental Plate
       • made of Granite
       • between 25Km and 90Km thick
       • 'floats' on a very hot mantle
   • Plate Margins
     • Destructive
       • Oceanic and Continental plates are pushed together
       • Earthquakes occur here due to fault line
       • Fold Mountains are made
     • Constructive
       • Oceanic or Continental plates pull apart
       • Creates Volcanoes
     • Conservative
       • Plates are pushed in different directions
       • Earthquakes occur here due to a fault line made
   • Restless Earth
     • Fold Mountains
       • formed on destructive plate margins
       • Geosyncline
         • A very large downfold in the Earth's crust which fills up over time with sediment
       • the rocks in the crust are compressed and folded into ANTICLINES (upfolds) and SYNCLINES (downfolds)
     • Volcanoes
       • Types of volcanoes
         • Shield Volcanoes
           • Found on Constructive plate margins
           • Basic Lava (1200C)
             • runny and flows long distances before cooling and soldifying
           • many eruptions form a coneshaped mountain with gently sloped sides
           • E.G Mauna Loa, Hawaii, USA
         • Composite Volcanoes
           • Acid Lava (800C)
             • thick and sticky
           • alternate eruptions cause ash followed by lava to build up a cone shape with steep sides
           • Found on Destructive plate margins
           • E.G Mt St Helens, Washington, USA
         • Supervolcanoes
           • found on Destructive plate margins
           • Massive explosions of ash form a sunken crater
           • ash would fall across the whole Earth killing everything
           • Yellowstone Caldera, Wyoming, USA
     • Earthquakes
       • The Cause
         • Plates are locked together via friction and pressure builds up over many years
         • the Crustal rock breaks suddenly underground causing a focus point in the rock
         • stored energy is released in seconds and travels outwards from the epicentre as shock waves
       • recorded in SEISOMETER
       • RICHTER SCALE measures the energy released
       • MERCALLI SCALE measures the damage done

2. Coasts

   • Waves
     • Destructive Waves
       • remove beach material
       • form in strong winds
       • BACKWASH is STRONGER than SWASH
       • a frequency of 11-15per minute
     • Constructive Waves
       • deposit beach material
       • form in light winds with calm conditions
       • SWASH is STRONGER than BACKWASH
       • frequency of 6-9per minute
   • Erosion
     • Hydraulic Power
       • force of the waves crashing in the cliff
       • air trapped in the cliff is compressed and fractures the rock
     • Solution
       • Rocks containing calcium carbonate slowly dissolve because of acidic water.
     • Attrition
       • pebbles are rolled backwards and forwards by waves
       • as they rub against each other they're slowly worn away
     • Abrasion
       • Sand and pebbles are thrown against cliffs by breaking waves and wear them away
   • Transportation and Deposition
     • Traction
       • boulders and cobbles are rolled along by powerful waves
     • Saltation
       • pebbles and sand are bounced around
     • Suspension
       • silt and clay are suspended in moving sea water
     • Solution
       • minerals are dissolved in sea water
     • Longshore Drift is the movement of material along a beach
   • Mass movement and Weathering
     • Sliding
       • Blocks of rock or loose material slide rapidly down the slope
     • Slumping
       • a mass of soil or clay slides downwards a curve slip-pane,
       • forms a scar on the upslope and a toe on the downslope
   • Landforms
     • Headlands and Bays
       • a headland is an area of land that sticks out into the sea
       • a bay is a curved coastal inlet
   • Hard engineering
     • building structures or machinery to control the natural processes
     • Sea walls
       • concrete walls designed to reflect the wave energy
     • Groynes
       • wooden built barriers built across the beach to trap the sand and pebbles transported via longshore drift
     • Rock armour
       • large boulders or resistant rock placed at the base of the cliff to prevent erosion
   • Soft engineering
     • working with the environment to modify or prepare for natural processes
     • Beach nourishment
       • beach material lost throughout longshore drift is replaced with material from further along the coast
     • Dune regenration
       • sand dunes are damaged by walkers or picnicker. areas of sand dynes are fenced off to allow them to re-grow naturally
     • Marsh Creation
       • areas of low economic value allow the sea to erode and flood the land.
         • this then develops mud flats, salt marshes, and beaches.

3. Living world

   • Weather and Climate
     • Depressions
       • areas of low pressure formed when air masses of different temperatures meet.
     • Anticyclones
       • areas of high pressure formed when an air mass is slowly sinking
   • Ecosystems
     • Nutrient Cycles
       • all living things need nutrients to live and grow.
       • the nutrients move through the ecosystem in a cycle
     • Energy Flows
       • plants and animals need energy to survive.
       • energy flows through an ecosystem along the food chain

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