Geography revision

• Mikolankovitch

  A process of change for the Earth's orbit and axis
• Sometimes the orbit is more oval shaped leading to cooler temperatures in the northern hemisphere
• During a cycle of average 40,000 years the axis varies from 22.1 to 24.1, the smaller the angle the less ice melts in the northern hemisphere
• Sun Spots may cause more magnetic activity at the surface which causes the sun to give off different amounts of energy
• Huge volcanic eruptions blast millions of tonnes of ash and gases into the atmosphere
• The ash spreads out blocking the sun for a short amount of time
• Gases like Sulphur dioxide which forms a sulphuric acid mist high in the atmosphere absorb sunlight keeping it from reaching the earth
• Greenhouse effect


  Greenhouse gases form a layer around the planet that stops heat from escaping into space
• About half the sun's radiation is absorbed by the atmosphere
• The rest bounces land and oceans
• The planet then radiates some of this heat towards space
• Some heat passes through the atmosphere but most is captured by the greenhouse gases
• Carbon Footprint


  The amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, country, etc.
• Climate Change


  The increase in global climate over a long period of time
• Drumlin


  A long, smooth, hill-shaped ridge created by a glacier
• Erratic


  A large rock that's different from those around it; it was carried there by a glacier
• Emissions


  The production of air pollution
• Food Miles


  The distance food travels between production and consumption
• Fossil Fuels


  Natural fuels such as coal or gas, formed millions of years ago
• Glacier


  A river of ice
• Global Warming


  The rise in global temperatures due to the increasing greenhouse gases in the atmosphere
• Greenhouse Effect


  A natural process that warms the Earth's surface
• Moraine


  Material (till) deposited by a glacier
• Ice Age


  Vast sheets of ice over a long period of time
• Non-renewable resources


  Resources that cannot be replaced or replenished
• Ice age


  A long period of time when the temperature decreases significantly, and thick ice sheets cover vast areas of land
• The last ice age began

  110,000 years ago
• The planet began to warm up and the ice age ended

  12,000 years ago
• The temperature did not rise steadily after the ice age ended
• The graph shows the average temperature for the northern hemisphere over the past 11,000 years
• Events happening in the cartoons


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• The red on the graph shows warmer periods, one of which occurs in the time of the Roman Empire
• The Medieval Warm Period allowed Vikings to settle in parts of Greenland
• The Little Ice Age occurred from around 1300 to 1850, during which some winters the River Thames froze over
• Today the average temperature in the Northern Hemisphere is around 15°C, but it is rising rapidly
• Modern humans (Homo sapiens) reached Britain around the time shown on the graph
• Ocean floor sediment


  Sediment builds up on the ocean floor over millions of years, containing examples like mud, shells or plants. It acts as a storybook for climate change.
• France had no ice sheets in the last ice age
• We are farmers
• Studying ocean floor sediment


  1. Drilling a core of sediments and studying them layer by layer

  2. Using radiometric dating to determine the age of a layer and the climate at that time