Relative Dating

• Evolutionary Changes in Fossils

  As time progresses, organism have evolved and become more complex
• Stratographic Methods


  Using the rock layers themselves
• Original Horizontally


  Most were deposited in water and laid down horizontally. We can assume that if layers have been seen vertical there has been movement
• Lateral Continuity


  Initially extended laterally in all directions.

  As a result rocks separated by a valley or another erosional feature must have been continous
• Principle of Superposition


  Rocks at the bottom of a sequence are always the oldest
• Included Fragments


  Fragments from an older rock can be found within younger rock
• Cross Cutting Relationships


  Features that cut through rocks must be younger than the rocks they cut through