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Geologic Time

Explore the 5-billion-year history of Earth and its life, from the birth of the solar system to the age of dinosaurs. Learn about super novas, the formation of planets, the evolution of life, and the changing landscapes over time.

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Geologic Time

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  1. Geologic Time The History of the Earth and It’s Life

  2. Birth of the Solar System. • 5 billion years ago (bya) a super giant star explods (super nova) creating a cloud of elements (nebula) made in the star’s core • Swirling cloud of dust and gas is pulled together by gravity • Nuclear fusion starts on the sun. • Denser parts of the cloud sweep up debris along their orbit eventually forming planets

  3. History of the Earth • The longest time periods are called eons. • Time measured in billion years ago (bya) Clock of Eons Phanerozoic

  4. Hadean Events • Event 1: Pressure and radioactive materials melt protoearth. • Event 2: Earth cools, first rocks become solid (like ice forming) • Event 3: Moon Forms • Event 4: Heavy bombardment of meteors and comets adds water and chemicals for life to early Earth. • Event 5: Crust covers entire Earth • Event 6: Crust cools enough for rain to become rivers, streams and oceans (first seasons)

  5. Hadean Atmosphere • Made from gases coming out of molten Earth • Poisonous to human life • No free oxygen to breathe • Lots of lightening

  6. Hadean Ocean • Salt comes from minerals dissolved by water (erosion) • Organic “soup” of molecules brought in during the heavy bombardment and natural processes

  7. Hadean Land and Life • Only one type of crust (basalt, like the oceanic crust today) • Faster plate tectonics • Only mountains are volcanoes • No life, only the molecules to make life (amino acids).

  8. From here on…The Data is in the Strata • The story of the Earth’s history is told in it’s layers • The rest of this presentation is a description of what we know from the layers We’re going to start with the oldest layers and work our way forward in time to today (top layer)

  9. Archean Eon: 3.8BYA to 2.5 BYA: Events • Sun 1/3 as bright • Planet 3 times hotter than today • First life • First protocontinents

  10. Archean Land • 3 billion years ago hot spot volcanoes erupt granite-like islands • First protocontinent is named UR • Oldest pieces of continental crust are, called “cratons” = shield • Several supercontinents may have formed, tectonics faster • First folded and faulted mountains form as continents collide

  11. Archean Eon: Atmosphere and Oceans • Atmosphere toxic to most life on our planet today, • Starts with no oxygen • Oceans warm (due to warm crust), more acidic than today (no carbonate rocks)

  12. Archean Eon = First Life • Our oldest fossils are bacteria that date to roughly 3.5 billion years ago • Cyanobacteria form stromatolites and use photosynthesis which produces 1st oxygen in air • 1st oxygen causes the first rusted iron in rocks

  13. Proterozoic Eon: Events, Atmosphere, Oceans • Life goes from simple soft bodied creatures to life with shells and armor plate. • Oldest evidence of ice ages • Oxygen levels equal to today • Atmosphere similar to today • Oceans similar to today

  14. Proterozoic Life: Part I • 1st life is single cell bacteria • Different types join together to form the first eucaryotic cell (symbiotic evolution) • Mitochondria are an example • Sexual reproduction begins, evolution goes faster

  15. Proterozoic Life Part II • Tissues and organs evolve next, first bodies are soft and squishy • Oldest evidence that skeletons and shells are evolving • Organs and organ systems evolve, and shells, armor, eyes, etc evolved. • Oldest known chordate (ancestor of backbone life: Pikaia)

  16. Proterozoic Land • First true continents and 2 supercontinents form then break up, first is Rodinia, next is Pannotia

  17. Phanerozoic Eon 575 m.y.a. - today Eons are divided into eras. There are three eras in the Phanerozoic Paleozoic = invertebrates to reptiles Mesozoic = Age of Dinosaurs Cenozoic = Age of mammals

  18. Paleozoic Era: Life “Explodes” • In many places the Cambrian is the first layer to have fossils, probably because hard parts evolved and conditions were good for fossilization. • Trilobites (first eyes) • Brachiopods, crinoids, ammonites, sponges, coral National geo

  19. Paleozoic: First Life on Land • 1st plants on land • 1st animals on land (arthropods)

  20. Paleozoic Era II The Age of Fishes • In the Devonian, fishes appear, evolve jaws and dominate the Oceans • In mammals the gills have become the jaw, inner ear bones and hyoid bone (which has no purpose)

  21. Paleozoic life III: Vertebrates Move onto Land • Legs and toes evolve from fins for moving through shallow swamps, amphibians crawl onto land and evolve into reptiles • Pangea joins together • Vast swamps form huge beds of coal

  22. Paleozoic IV: • Therapsid reptiles evolve into reptiles, protomammals, and protodinosaurs • Dimetrodon, and early mammals ruled at the end of the Paleozoic

  23. Mesozoic Era Dinosaurs Dominate the Land • Mammals are mostly small and nocturnal • First birds and Flowers • Pangea splits up

  24. Mesozoic: Age of Dinosaurs • Many or all were warm blooded. • Chinese fossils show many may have had feathers • Not all dinosaurs are extinct: birds still live. Chinese Photo Gallery

  25. Mesozoic Era II: Ends Extinction of Most Dinosaurs Causes of dino extinction • Many suspect a comet or asteroid that landed near the Yucatan put so much ash into the atmosphere that it altered the climate. • Disease, continental drift, volcanic activity and competition are other suspects

  26. Cenozoic: Mammals Take Over • Early mammals evolve into many forms including giant Pantotheres • Mammals develop unique teeth and start preying upon each other.

  27. The Oldest Known Upright Walking Primate Footprints • 3.6 million years ago years ago ash spewed from an African volcano • A family of three walked across the fresh ash. The female stepped on the males footprints, and a youngster occasionally walked on its own. • They were hominids, a type of ape that walks on two feet. • Their species is nicknamed “Lucy” after the first fossil found.

  28. Cenozoic Humans Evolve • Homo habilis: Handy man made stone tools • Homo erectus: made better tools • Homo neanderthal : Cave man: buried their dead with tools and flowers

  29. Homo Sapiens: Recorded History • Our species evolved in Africa and migrated from there • They developed art… • and religion

  30. Cenozoic: Recent Life • Most of Oregon forms • Last Ice Age • Missoula floods • Recorded history i.e. Social Studies, begins.

  31. Cenozoic Animals • Mammals dominate

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