geo exam

• • Cold origins
  • cold cloud of dust & gasses condensed due to gravitational pull & formed earth 
• Nebular hypothesis


  5-6 bil yrs ago in our galaxy a solar nebula & its rotation gravity made materials condensate to center of disk piling on & increasing temperature that caused the sun to form
• • Solar nebula

  • large rotating disk of dust & gasses that rotates by motion of galaxy 
• • Planetesimals

  • orbit sun & occasionally collide w each other & grow making protoplanets 
• protoplanets


  initial planets of solar system that didn't crash into each other & evolve to make the planets
• Wave increases


  Suggests high density beneath upper crust
• Lithosphere


  Surface of the earth down to the moho & the high velocity area under moho
• Asthenosphere


  Low velocity zone just beneath lithosphere, part molten part solid
• Mesosphere


  Beneath asthenosphere that is solid & very hot
• Inner & outer core


  Beneath mesosphere, outer is thought to be liquid
• Magnetic field formation


  1. Outer core rotates eastward

  2. Solid inner core rotates faster than outer core

  3. Molten material (iron, electrically charged) of inner core moving around center of earth as its rotating
• Core of earth


  Made of iron nickel
• Formation of crust


  1. Chemical/ density differentiation

  2. Denser materials are pulled towards center of earth
• Outgassing hypothesis


  Lighter materials through chemical differentiation by volcanoes that if temperature is right can form water while gasses flow upwards
• Cyanobacteria


  Organisms that first ejected o2 through photosynthesis
• Amber


  Lithified tree resin that attracts insects that get stuck in the sap
• Mummification


  Shriveling of soft tissue due to dehydration
• Freezing


  Organism would get stuck on snowstorm and end up dying within the ice
• Peat


  Woody material that accumulates faster than it decomposes in swamps
• Tar


  Seeping oil that traps organisms
• Permineralization


  When mineral matter seeps into pores of bones, teeth after death
• Recrystallization


  When unstable compounds recrystallize to more stable compounds, no composition change
• Replacement


  Original skeletal material is replaced by compound of different composition
• Carbonization


  When volatile elements of organic material vaporize & leave behind carbon film
• Disconformities


  Unconformity between two sedimentary rocks
• Nonconformities


  Unconformity between sedimentary rock & a different kind of rock
• Angular disconformity


  Tilting of strata
• Uniformitarianism


  Theory that states the present is key to the past, earth's history is delicately balanced
• Superposition


  • Oldest rocks at the bottom
• Original horizontality


  • Sediments are originally deposited horizontally, any inclines is later deformed
• Lateral continuity


  • Strata extended all around til they are thinned out
• Drift evidence


  • oceanic ridges
  • paleomagnetism
  • sea floor age
  • hot spots
  • flora & fauna
  • stratigraphic successions
• Geological scale hierarchy


  Oldest period/era on bottom
• Igneous intrusive


  Cooled magma & crystalline structure
• Igneous extrusive


  Cooling lava & glassy texture
• Metamorphic


  Any rock changed by intense heat, pressure & fluids under crust
• Sedimentary detrital


  Solid particles once apart of another rock
• Sedimentary chemical


  Accumulation of biological/ inorganic chemical precipitants
• Absolute dating


  Uses radioactive decay time of specific elements
• Alpha decay


  Loss of 2 protons & 2 neutrons, atomic # decreases 2 & atomic mass by 4