GEOLOGIC TIME SCALE

• is a record of the life forms and geological events throughout earth's history

  geologic time scale
• preserved remains of a once-living organism

  fossils
• study of fossils and ancient life

  paleontology
• 4 steps of being a fossil

  1. quick burial
  2. replacement
  3. movement
  4. erosion
• organism is buried suddenly preventing decay

  quick burial
• as layers accumulate, minerals in the remains such as bones are replaced

  replacement
• in replacement, calcium phosphate is replaced by

  pyrite
• uplift causes the fossil layer to surface

  movement
• fossil is exposed to the surface

  erosion
• types of fossils

  petrified fossil

  mold and cast

  trace fossils

  preserved remains

  carbon imprint
• preserved close to their original state

  preserved remains
• fossils which mimickes activties of organisms

  trace fossils
• mold is the imprint

  cast is the result of mold
• all or part of an organism replaced by minerals

  petrified fossil
• largest time

  eonothem/eon
• time is divided into 2 eons

  precambrian

  phanerozoic
• precambrian eon is dvided into 3 eras

  hadean

  archaean

  proterozoic
• phanerozoic eon is divided into 3 eras

  paleozoic

  mesozoic

  cenozoic
• paleozoic era is divided into 6 periods

  cambrian

  ordovician

  silurian

  devonian

  carboniferous

  permian
• mesozoic era is divided into 3 periods

  triassic

  jurassic

  cretaceous
• cenozoic era is divded into 3 periods

  paleogene

  neogene

  quaternary
• paleogene period is divided into 3 epochs

  paleocene

  eocene

  oligocene
• neogene period is divided into 2 epochs

  miocene

  pliocene
• quaternary period is divided into 2 epochs

  pleistocene

  holocene
• oldest and longest eon

  precambrian eon
• represents earth's earliest history

  hadean era
• marked by extreme magmatism, earth's differentiation, and heavy meteorite bombardment

  hadean era
• era.

  formation of the moon and formation of first continents

  archaean era
• oldest dated rock

  acasta gneiss
• era. existence of biological signatures

  archaean era
• era. existence of stromatolites

  archaean era
• built up by ancient cyanobacteria

  stromatolites
• simulated early earth's atmosphere and lightning within a sealed vessel

  miller-urey experiment
• what were formed during the miller-urey experiment?

  amino acids
• bacteria that introduced oxygen in the surface of the earth


  cyanobacteria
• era. rapid increase of oxygen gradually cooled down the earth

  proterozoic
• era. snowball earth

  proterozoic
• era. formation of ironstones

  proterozoic
• era. existence of vendian and ediacara fauna

  proterozoic
• eon. marked by explosion of life

  phanerozoic