Natural Environment - Concepts - Chapter 1 Class 7 Geography - Our Environment - Geography

Natural Environment 

• Natural environment: includes biotic (living) and abiotic (non-living) components
  
  
• Biotic components: plants and animals
  
  
• Abiotic components: air, water and soil

Four Major Domains of the Earth are 

• Lithosphere

•  rocky outermost layer of the earth
• Includes crust and upper part of mantle
• Average thickness: 100 km
• Made of rocks, minerals and soil
• Forms landforms on continents and ocean basins
• Provides land for building, agriculture and resources

• Hydrosphere

  • water present on the earth’s surface
  • Includes oceans, seas, bays, lakes, rivers, etc.
  • Also includes groundwater below the surface
  • Supports all forms of life
  • Water found in three states: solid, liquid and gas
  • Freshwater available through water cycle

• Atmosphere

  •  envelope of air surrounding the earth
  • Held by gravity
  • Contains oxygen, carbon dioxide and other gases
  • Prevents harmful rays from reaching the earth
  • Controls temperature and weather
  • Without atmosphere, earth would be barren

• Biosphere

  • narrow zone where lithosphere, hydrosphere and atmosphere meet and interact
  • Supports life and is called the living world
  • Consists of plant and animal kingdom
  • Small in size but has many species of organisms
  • Provides nutrients and resources to living beings