geologic time

  1. principle of superposition
    old on the bottom young on the top
  2. principle of original horizontality
    every layer starts out horizontal. 
  3. principle of cross cutting relationships
    james hutton discovered that the new rocks cut the old. You have to put the relationships at the end or will get it wrong
  4. principle of fossil succession
    also Faunal Succession. William Smith. Organisms change from simple to complex over time
  5. principle of Inclusion
    also James Hutton. Fragments in a rock body are older than the rock that contains them
  6. Difference between relative and absolute dating
    • relative uses the 5 principles and just puts things in chronological order. it does not use any numerical ages.
    • absolute uses radiometric methods to get an exact age
  7. what is angular unconformity
    sedimentary rock layers that are not horizontal due to deposition deformation erosiaon and renewed deposition.
  8. what is disconformity
    sedimentary rock the beds are horizontal
  9. what is nonconformity
    sedimentary rock in contact with metamorphic or igneous rock
  10. who invented radio activity
    henri becquerel in 1896
  11. what is half life
    • the rate of decay for an isotope.
    • every time the isotope decays in half the same time has gone by regardless of the size
    • Exponential NOT Linear
  12. what is the nebular hypothesis
    the earth and solar system formed from an exploded star
  13. how were oceans created
  14. what is accretion
    coming together of smaller ilandmasses into larger ones.
  15. what were the prokaryotes
    Blue Green algae which produced tons of caco3 called stromatolites
  16. when was precambrian era
    4.6 billion to 570 million years ago
  17. order of eras
    • precambrian
    • paleozoic
    • mesozoic
    • cenozoic
Card Set
geologic time
geologic time