Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Relative Dating


Published on

You are as old as dirt or are you?

Published in: Education
  • Be the first to comment

Relative Dating

  1. 1. Relative Dating Chapter 13 Clues to Earth’s Past
  2. 2. Rules of Relative Dating <ul><li>Law of Superposition – the youngest layers are on the top and oldest on the bottom. </li></ul><ul><li>Layers are always laid down flat. </li></ul><ul><li>Uniformitarianism – processes happened in the past just as they happen today. </li></ul><ul><ul><li>Volcanic eruptions </li></ul></ul><ul><ul><li>Erosion </li></ul></ul><ul><ul><li>Fault movement </li></ul></ul><ul><li>Look out for unconformities !!! </li></ul><ul><li>*layers that are missing from erosion </li></ul>
  3. 3. Cross-cutting Relationships <ul><li>Intrusions –magma comes up into faults or between layers ( the layers were there 1 st ) </li></ul><ul><li>Faults crack the layers after they have formed ( the sidewalk is there before the crack ) </li></ul><ul><li>Folding of rock layers happens after they have been laid down flat. </li></ul>
  4. 4. 3 types of unconformities <ul><li>Like pages missing from the middle of a book </li></ul><ul><li>Erosion takes away layers leaving a gap in the rock record. </li></ul><ul><li>Correlation of rock sequences – by comparing rock layers from different areas a complete record of layers can be determined. </li></ul><ul><li>3 types </li></ul><ul><ul><li>Angular unconformity </li></ul></ul><ul><ul><li>Disconformity </li></ul></ul><ul><ul><li>Nonconformity </li></ul></ul>
  5. 5. Angular unconformities <ul><li>Horizontal sedimentary layers are TILTED when they are uplifted then eroded. </li></ul><ul><li>New sedimentary layers are deposited on top of this erosional surface. </li></ul><ul><li>Look for angles in the lower rock layers! </li></ul>
  6. 6. Disconformity <ul><li>Sedimentary rock layers were uplifted and eroded. </li></ul><ul><li>New sedimentary layers were added on top of this erosional surface. </li></ul><ul><li>The layers are ALL parallel. </li></ul><ul><li>There is a gap in the rock record. </li></ul>
  7. 7. Nonconformity <ul><li>Igneous or metamorphic rocks are uplifted and eroded </li></ul><ul><li>Sedimentary rocks are deposited on top of this erosion surface </li></ul><ul><li>The surface between the 2 different rock types is a nonconformity. </li></ul>
  8. 8. Which came first?
  9. 9. Answer key 1 2 3 6 4 8 9 11 12 7 5 10 13 erosion 6 intrusion 7 unconformity 10 fault