SCIENCE LESSON 1

• Plates


  Sections of the Earth's crust and upper mantle that move around on top of the mantle like rafts
• Lithosphere


  Earth's crust and upper mantle that are broken into sections and move around on top of the mantle
• Plate tectonic theory

  1. Pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle

  2. Plates move slowly in different directions

  3. Cause different geologic events like earthquakes and volcanoes
• What makes plates move?

  Convection currents in the mantle move the plates as the core heats the slowly-flowing asthenosphere (elastic/plastic like part)
• Mountain ranges


  • Formed by a variety of geologic processes, but the most significant ones are the result of tectonic plates
  • Series of mountains arranged in a line and connected by high ground
• Mountain system / Mountains belt


  A group of mountain ranges with similarity in form, structure, alignment that have risen from the same cause, usually an orogeny
• Mountain chain


  Consists of mountain ranges which differ in size and period of time
• Cordillera


  A community of mountains includes ridges, ranges, mountain chains and mountain systems, e.g. the Western cordillera in western North America
• Layers of Earth's lithosphere

  • Crust
  • Upper part of mantle
• Crust


  • Made of a variety of solid rocks including sedimentary, metamorphic and igneous
  • Average density = 2.8 grams per cubic centimeter
  • Thickness ranges from 5 to 50km, thickest where there are young mountains and thinnest along the ocean floor
• Continental crust


  Thicker, less dense, composed of granitic rocks made up of lightweight minerals like quartz and feldspar