Rocks and Minerals

• Rocks


  Solid parts of the earth that can be very different from each other
• Rocks


  • Composed from combinations of minerals that have formed naturally over time
  • Can be classified as igneous, sedimentary, or metamorphic
• Rocks


  • Granite
  • Coal
  • Marble
  • Petroleum
• Minerals


  Elements that rocks are made up of
• Minerals


  • Have important physical properties like hardness, shape, luster, and color
• Minerals


  • Diamond
  • Talc
  • Quartz
  • Gold
• Rocks and minerals have been used since prehistoric times for making utensils, building houses, paving, and making jewelry
• Rocks are formed from minerals and both rocks and minerals are part of nature and the landscape that surrounds us
• Relative rock dating


  Determining the relative or comparative age of rocks to each other, knowing which is older and which is younger but not the exact age
• Absolute or radiometric rock dating

  Determining the exact age of a rock
• Relative rock dating laws

  1. Law of superposition

  2. Law of cross-cutting

  3. Law of inclusions
• Law of superposition


  In an undisturbed sequence of rocks, the oldest rocks are on the bottom and the youngest rocks are on top
• Laundry basket analogy


  Oldest clothes on bottom, youngest on top
• Law of cross-cutting


  Any feature that cuts across the sequence of rocks is younger than everything it cuts
• Tracks in snow/sand analogy


  Older tracks covered by younger tracks
• Law of inclusions/included fragments


  Any rock or fragment included inside another rock is older than the rock it's included in
• Fruitcake analogy


  Chunks in fruitcake are older than the surrounding cake
• Relative rock dating laws help determine the sequence of events that led to rock formation