The Ever Changing Earth

• Structure of the Earth - THE INNER CORE

  • The hottest part of the Earth
  • Temperatures up to 5,500 •c
  • Made of primarily of Iron with some Nickel
• Structure of the Earth - THE OUTER CORE

  • Liquid layer
  • Made of Iron and Nickel
  • Bearly as hot as the inner core
• Structure of the Earth - THE MANTLE

  • The thickest part of the Earth
  • Contains Semi-molten rock
  • More solid towards the outer edge of the mantle
  • More molten towards the core
• Structure of the Earth - THE CRUST

  • The thinnest part of the Earth
  • It’s thickness varies but can be up to 70km
• PLATE TECTONICS

  Over billions of years ago the Earth has continuously changed.

  These changes are often slow.

  2 Million years ago the Earth‘s continents were one block called Pangaea.
• TECTONIC PLATES - Is the crust and the upper mantle, fragmented into large pieces.
• TECTONIC PLATES

  • They float on the mantle
  • Don’t stay in one place
  • Convection Currents cause the plates to drift
  • They move at the speed of a few cm per year
  • Plates can move suddenly = earthquakes
  • Volcanoes and earthquakes occur between boundaries of two plates
• Structure of the Earth - The Earth’s outer layer, Lithosphere is broken into 7-8 major and many minor plates
• Alfred Wegener - In 1914, he hypothesised that Africa and South America had previously been one Continent
• Alfred Wegener - EVIDENCE FOR HIS THEORY

  • Matching layers of rocks on BOTH continents
  • Similar Earth Worms living in both continents
  • Fossils found on opposite sides of the Atlantic Ocean were very similar
  • Similar plants and animals that had Common ancestors
  • The coast line of Africa and South America seems to fit together like a jigsaw
• Alfred Wegener - didn’t have any evidence on how the continents moved
• Alfred Wegener - 1930s to 1960s the idea of convection currents below the crust was researched and was then finally accepted as the true mechanism for plate tectonics.
• Africa and South America

  
• Plate Boundaries - There are 3 types of movement between plates

  • Destructive
  • Constructive
  • Conservative
• Plate Boundaries - DESTRUCTIVE PLATE BOUNDARY

  • 1 plate is pushed down into the mantle and then melts to form magma
  • This can create explosive Volcanoes
  • The ocean floor is denser than below the continent
  • Thats why the oceanic crust sinks below the continental crust ( this is called subduction ).
  • Fold mountain often form along the boundary.
  • When the molten rock frim volcanoes cools and solidifies it forms an igneous rock
• Plate boundaries - CONSTRUCTIVE PLATE BOUNDARY

  • Plates can move apart
  • when that happens molten rock (magma) from below the surface is released
  • The magma can cool and form an Igneous rock
  • A volcanic explosion can occur if that happens under pressure
  • If that occurs at mid-ocean ridge new islands can form
  • Iceland is an example of an island being formed mid-ocean ridge
• Plate boundaries - CONSERVATIVE PLATE BOUNDARY

  • Plates slide past each other
  • Powerful earthquakes can be generated here
  • No volcanoes are present
  • No rock melting occurs
  • Example of this boundary is San Andreas Fault in California
  • A lot of architecture must incorporate earthquake - proofing
• Destructive plate boundary

  
• Constructive plate boundary

  
• Conservative plate boundary

  
• The Atmosphere - CREATION OF THE ATMOSPHERE

  1. Volcanoes released carbon dioxide, ammonia and water vapour, which formed the first atmosphere.
• The Atmosphere - CREATION OF THE ATMOSPHERE

  2. The Earth cooled, causing steam to condense and form the ocean. (Occurred much quicker than the other changes )
• The Atmosphere - CREATION OF THE ATMOSPHERE

  3. Photosynthesis and Bacteria formed in the oceans.
• The Atmosphere - CREATION OF THE ATMOSPHERE

  3a. Bacteria consumed Co2, causing levels in the atmosphere to decrease.
• The Atmosphere - CREATION IF THE ATMOSPHERE

  4. Bacteria released Oxygen in the atmosphere, causing O2 levels to increase.
• The Atmosphere - CREATION OF THE ATMOSPHERE

  5. Oxygen reacts with Ammonia which forms Nitrogen
• The Atmosphere - CREATION OF THE ATMOSPHERE

  5a. Nitrogen is the most abundant gas in the atmosphere.
• The Atmosphere - CREATION IF THE ATMOSPHERE

  6. Ozone, or O3, was formed when Oxygen combines
• The Atmosphere - CREATION OF THE ATMOSPHERE

  6a. Ozone prevents ultraviolet light from entering Earth and forms a protective layer which helps prevent skin cancer.
• Current Composition -

  • Nitrogen 78%
  • Oxygen 21%
  • Argon (+ noble gases) 0.9%
  • Carbon dioxide 0.04%
• Current Composition - green plants evolve —> photosynthesis consumes the original Carbon dioxide from initial atmosphere
• Current Composition - Evolution of marine animals = locked carbon dioxide into limestone and chalk from their shells
• Current Composition- carbon dioxide was locked into fossil fuels from the remains of marine organisms and larger land plants
• Respiration, Combustion and Photosynthesis - stable composition of the atmosphere before humans increased combustion


  Photosynthesis -

  Co2 in — —> O2 out

  =

  Reporation and combustion -

  O2 in — —> Co2 out
• Respiration, Combustion and Photosynthesis - composition of the atmosphere after humans increased combustion


  Photosynthesis -

  Co2 in — —> O2 out

  🚫=🚫

  Respiration and Combustion

  O2 in — —> Co2 out
• Respiration, Combustion and Photosynthesis - HOW HUMANS INCREASED COMBUSTION

  • burning fossil fuels
  • decreasing photosynthesis due to deforestation
• Environmental Issues - CARBON DIOXIDE

  • due to emissions of increased levels of Co2 —> higher temperatures = Global Warming
  • Co2 prevents heat from escaping
• Environmental Issues - GLOBAL WARMING CAN CAUSE

  • Changing weather patterns - summers in some of the world leading to drought, drier, hotter
  • Flooding - increased rainfall
  • Ice caps and Glaciers melting quicker
  • Rising sea levels
• Environmental Issues - CARBON CAPTURE -

  • scientists thinking of storing Co2 ( that’s been produced by fossil fuels ) under the sea or underground
  • Best way of reducing Co2 is to become ’responsible consumers’ if energy - utilise alternative energy sources
• 1. Environmental Issues - SULFUR DIOXIDE

  • Forms burning impurities within fossil fuels
  • sulfur dioxide in the atmosphere forms acid rain
  • acid rain lowers pH of lakes, rivers and ponds —> damaging the aquatic life, forests and vegetation.