Geologic Time Scale

• Geologic Time Scale


  Chronological arrangement of events throughout the earth's history through radiometric dating
• Eons of Earth

  • Hadean - Hades means Hellish (remains theoretical)
  • Archean - Archaios means Ancient
  • Proterozoic - Proteros means earlier
  • Phanerozoic - Phaneros means visible
• Hadean Eon


  • Formation of Earth and moon, core accretion, formation of magnetic field, formation of geosphere
• Archean Eon


  • Formation of atmosphere, continent began to form (Vaalbara) - first continent and ocean, rise of photosynthetic prokaryotes (unang buhay) (atmosphere oxygenated for the first time)
• Proterozoic Eon

  • Rapid oxygen build up (formation of ozone), oxygen crisis (over supply of oxygen), rise of eukaryotic (via cellular respiration) and multicellular organism
• Phanerozoic Eon


  • Life diversification, experienced series of mass extinctions, most recent eon
• Bakit hindi "phyta" (plants) binase yung names sa Phanerozoic? Kasi based sya sa fossilized animals na an dugged up.
• Paleozoic Era

  • Age of "ancient life" (Popular name: Age of Invertebrates) (no backbone)

  
• Cambrian Period

  • Rapid diversifications of invertebrates - "Cambrian Explosion", Algae blooms - "Age of Algae", Life start: Algae, Chytrids, Protozoa
• Ordovician Period


  • Appearance of first vertebrates (fish), First Mass Extinction event, 85% of marine life died (Ordovician Silurian Mass Extinction Event) 15% na natira, sila yung nagparami sa Silurian
• Silurian Period


  • Land invasion of algae (naging plants after), appearance of insects crawlers (prey) in land
• Devonian Period


  • Age of Fish and appearance of amphibians, Second Mass Extinction event, 80% of marine life died (Devonian Carboniferous Mass Extinction Event)

  
• Carboniferous Period


  • Coal formation, rise of reptiles, seed plants, flying insects appears
• Permian Period


  • Pangea forms, Third Mass extinction (The Great Dying), 96% of organisms died (Permian–Triassic Mass Extinction Event)
• Mesozoic Era


  • Age of "Middle Life" (Popular Name: Age of Reptile)
• Triassic Period


  • First land dinosaur and mammals appears (small in size), Fish like reptiles appears, Gymnosperms (non flowering plants) appear, Pangea breaks apart, Fourth mass extinction, 76% of species died
• Jurassic Period

  • Bird like reptiles appears, Golden Age of Dinosaurs (large reptiles dominates both air, land and water regions)
• Cretaceous Period


  • Angiosperms (flowering plants) evolved, first primates appear, Fifth mass extinction (K-T Mass extinction), 76% of species died
• Dunkleosteus


  • Largest fish during Paleozoic era, apex predator
• Vertebrate evolution

  • Fish
  • Amphibians
  • Reptiles
• K-T Extinction

  K - Abbreviation for Cretaceous Period, derived from the German name Kreidezeit; T - Abbreviation for the Tertiary Period.
• K-T boundary sedimentary band all over the world has iridium (sa mexico) ranging from 20-160 times normal amount; Iridium is rare in Earth's crust, but abundant in asteroids/comets.
• Chicxulub crater - impact site, located in Mexico
• Common organisms that lived during the Mesozoic era

  • PROCONSUL - Ancestor to Hominids
• Cenozoic Era

  • Age of "Recent life" (Popular name: Age of Mammals) *still continues until now
• Tertiary Period


  • Reign of Mammals
• Paleogene Period


  • Large diversification of mammalian species
• Neogene Period 


  • Appearance of man
• Meios - less
• Pleistocene

  • Mammals begin to migrate
• Pleistocene Epoch


  • Ice Age - happened during Pleistocene epoch; mammals migrate
• Holocene Epoch


  • People developed intelligence and learned to domesticate animals and cultivate plants
• Paul Crutzen in 2000, proposed that the Holocene Epoch is over and a new geological epoch called the ANTHROPOCENE Epoch has begun (started 1800's)
• Man's impact on the Earth's climate and ecosystems since the Industrial Revolution (build up own engine) is quite evident. Support for this theory comes from data derived from glacial ice cores showing the growth in greenhouse gases starting from the 1800's
• Pangea existed when some of the earliest dinosaurs were roaming the Earth. It was surrounded by a sea called Panthalassa, meaning "all sea"


  245 Million Years Ago
• Gradually Pangea broke into two big pieces. The northern piece is called Laurasia. The southern piece is called Gondwana


  180 Million Years Ago
• By the time the dinosaurs became extinct, Laurasia and Gondwana had split into smaller pieces

  65 Million Years Ago