Geol

• Deep Time

  the immense span of geologic time
• James Hutton was called...

  the father of modern geology
• Who was the first to articulate the "principle of uniformitarianism"?

  James Hutton
• What is James Hutton's principle of uniformitarianism?


  "The present is the key to the past"
• What are the 2 ways to date geologic materials

  relative ages, numerical ages
• Relative age


  based upon order of formation, determination of older vs. younger relationships, developed hundreds of years ago
• Numerical ages


  actual number of years since an event, developed recently.
• Who created a set of principles for deciphering earth history?

  Sir Charles Lyell
• The principle of uniformitarianism


  processes observed today were the same in the past
• Principle of Original Horizontality

  Sediments settle out of a fluid by gravity.
• Tilted sedimentary rocks are _______.

  deformed
• The principle of superposition


  Younger strata are on top and older strata on bottom
• The principle of lateral continuity.


  Subsequent erosion dissects once-continous layers
• the principle of cross-cutting relations


  Younger features cut across older features
• principle of baked contacts


  a igneous intrusion cooks the invaded country rock. The baked rock must have been there first (it is older).
• Principle of Inclusions (rock fragments within another)

  Inclusions are always older than the enclosing material.
• Physical principles allow us to

  sort out relative age even in complex situations.
• Fossils are preserved in ________ rocks.

  sedimentary
• Fossils are ____ _____ for relative age-dating.

  time markers
• First _________, _________, and _______ are used for dating

  appearance, range, extinction.
• Fossil Range


  the first and last appearance, each fossil has a unique range
• ______ fossils are diagnostic to a geologic time.


  index
• Unconformity


  a time gap in the rock record from erosion and non deposition.
• an unconformity is a time gap in the rock record from

  erosion and nondeposition
• 3 types of unconformity

  angular, nonconformity, disconformity
• what does angular unconformity represent

  a huge gulf in time. Horizontal at first, new mountain range, eroded mountains, new horizontal layers.
• Angular unconformity process


  Horizontal layers first, then a mountain range formed and eroded, then new horizontal layers form on top.
• nonconformity


  igneous/metamorphic rocks capped by sedimentary rocks.
• nonconformity process


  igneous or metamorphic rocks were exposed by erosion, sediment was deposited on the eroded surface.
• Disconformity


  parallel strata bounding nondeposition. Often hard to recognize
• Disconformity process


  An interruption in sedimentation, pause in deposition, sea level falls then rises, erosion
• Eons


  the largest subdivision of time, not consistent number
• Eras


  subdivisions of an eon
• Periods


  subdivisions of an era
• epochs

  subdivisions of a period
• Phanerozoic (Eon)


  visible life
• Proterozoic Eon


  before life
• Archean eon


  ancient
• hadean eon


  hell
• Cenozoic era

  "recent life"