Impact Craters

• Meteor Crater (Barringer) Arizona Fig. 3

  • First impact crater identified 1920’s
    • 25,000 y. old -- very fresh
  • many (eroded) craters found on earth
    • oldest 1 billion y. -- weathering and tectonic activity

• Maria (dark, few craters) vs. highlands (many craters)

  • maria are youngest regions on Moon Fig. 5

• Tycho crater (100 km, young) -- typical crater

  • perfect circle Fig. 6
  • raised walls
  • flat, depressed floor
  • mountain in center
  • radial rays -- ejecta

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