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GEOLOGIC TIME

GEOLOGIC TIME. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Eon : largest segment of geologic time; i.e. Archean, Proterozoic, Phanerozoic.

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GEOLOGIC TIME

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  1. GEOLOGICTIME

  2. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Eon: largest segment of geologic time; i.e. Archean, Proterozoic, Phanerozoic

  3. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Era: subdivision of an eon; i.e. Paleozoic, Mesozoic, Cenozoic

  4. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Period: subdivision of an era; i.e. Quaternary, Tertiary

  5. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Epoch: subdivision of a period; i.e. Holocene, Pleistocene

  6. The Earth is 4.55 billion years old. Just like we break our year up into months, weeks, days, minutes and seconds, we break up geologic time into pieces so we can better understand it. Each separate division of time is different from the others, by plant or animal life types that have evolved over time from single-celled organisms to complex multi-cellular critters like you!

  7. Atmosphere, climate and continents have changed all throughout geologic time!

  8. True Division of Geologic Time Time in Billions of Years Ago

  9. PRECAMBRIAN 4550-570 mya • Hadean • Archean • Proterozoic

  10. Precambrian Famous for: • Formation of Earth • Oxygen atmosphere forms • Single-celled, algae and wormlike organisms • Remaining rocks are severely bent & folded, so hard to read • Several different glacial periods

  11. THE EARTH FORMS 4.5 BYA Volcanic outgassing releases carbon dioxide, water & other gasses into the atmosphere, marking the beginning of the Precambrian. There is little or no oxygen in the early atmosphere.

  12. Slowly, over billions of years, the Earth cools and rain falls to further cool & solidify the lava. Early bacteria evolve, releasing oxygen into the air. This allowed oxygen-breathing organisms to evolve.

  13. Banded Iron Formation What type of chemical weathering is this? OXIDATION Precambrian iron deposits show banding with iron oxide (rust) due to increased oxygen in the atmosphere & water.

  14. Paleozoic 570-245 mya Cambrian thru Permian

  15. Explanation of Adaptation & Evolution

  16. Paleozoic Famous for: • Beginning of abundant life • Coal deposits • Ends with major extinction & formation of Pangaea • Between the Paleozoic and the Mesozoic, nearly 95% of all species on Earth died off. • The cause or causes of this extinction include: volcanism & climate change

  17. Possible Causes of Permian Extinction • Extensive glaciation • Lower sea level, so less aquatic environment available • Volcanic eruptions putting sulfur & ash clouds into air, blocking sunlight

  18. Paleozoic Climate: • Ordovician: North America was on equator & had warm inland seas • Silurian: North America became very dry, leaving huge salt deposits • Carboniferous: lots of freshwater swamps that left coal deposits in the east • Permian: very dry climate and great ice age

  19. Trilobites

  20. AGE OF FISHES

  21. mesozoic 245-66.4 mya • Triassic • Jurassic • Cretaceous

  22. Mesozoic Famous for: • Dinosaurs beginning in the Jurassic • Ends with MAJOR extinction of over 50% of all organisms from meteorite impact • Pangaea begins to break up Climate: • Mild climate, with very little glaciation • Forests grew at the poles, and coral in Europe

  23. DINOSAURS

  24. cenozoic 66.4 mya - now Tertiary & Quaternary periods

  25. Cenozoic Famous for: • Age of Mammals • Humans evolve

  26. CEnozoic Climate: • Tertiary: warm and humid, but temperatures slowly decreasing until one quarter of the land was covered in ice (the Great Ice Age) – forests become grassland • Quaternary: cycles of warming & cooling – we’re now in a warm period (only 1/10th of the area that used to be ice still is!)

  27. Humans (Hominids) Australopithecus • Oldest hominid – 5mya • Apelike brains, humanlike jaw, bipedal

  28. Humans (Hominids) Homo habilis • 2mya • larger brain, used simple tools

  29. Humans (Hominids) Homo sapiens • 400,000y - today • Larger brains • Current humans are in this group

  30. DINOSAURSandHUMANSdidNOT coexist! Dinos died out 67 million years ago, while humans have only been around 5 million years. Sorry, but the Flintstones are a lie!

  31. Climate Change Earth’s average temperature has increased dramatically since the Industrial Revolution started releasing more CO2 and other greenhouse gases into our atmosphere. These gases act as a blanket that trap heat and increase global average temperatures.

  32. Climate change Seems to be relationship between CO2 & temperature But, is the recent increase unusual? Or common?

  33. Climate Change Earth’s climate has changed repeatedly throughout geologic time. The question, though, isn’t whether the recent increase is unusual but if the recent increase is going to hurt our current way of life. The answer to that question is yes.

  34. Climate Change: effects • Sea level rises, causing increased flooding along coastlines • More severe storms • Droughts in certain areas • Loss of plant & animal species

  35. Homework Review • What are the segments of geologic time, from largest to smallest? • What gas, required for human life, was not originally part of the atmosphere but was added later by anaerobic bacteria? • What era marked the beginning of abundant life? • How old is the Earth? • How long have dinosaurs been extinct? How long have humans existed? Did they coexist? • Does the climate of an area change over time, or has it always been the same? • Over geologic time, are organisms getting more or less complex?

  36. Absolute Dating • Determining the actual dates for events & how old they are • Counting by how many years ago something happened

  37. Counting the Years • Tree rings • Varves& Ice Cores How does this help us understand the past?

  38. Radioactive Decay

  39. Radioactive dating Half-life: the time it takes for half the radioactive atoms in a sample to decay to a stable product 0 1 2 3

  40. Radioactive dating If half-life of element is 20 years, how old is a 100g rock containing only 25g of the parent element? If the half-life is 100 years, how old is the same rock? 0 1 2 3

  41. Radioactive Decay http://www.colorado.edu/physics/2000/isotopes/radioactive_decay3.html

  42. Isotopes Used in Radiometric Dating Parent Isotope Daughter Isotope Half-life (years) Effective Range (yrs) Possible Materials for Dating Carbon-14 Nitrogen-14 5730 100-70,000 Once-living matter Uranium-238 Lead-206 4.5 billion >10 million Uranium-bearing minerals (zircon) Rubidium-87 Strontium-87 47 billion >10 million Micas, feldspars, metamorphic rocks Potassium-40 Argon-40 1.3 billion >50,000 Micas, amphiboles, feldspars, volcanic rocks

  43. What are the segments of geologic time, from largest to smallest? • What gas, required for human life, was not originally part of the atmosphere but was added later by anaerobic bacteria? • What era marked the beginning of abundant life? • How old is the Earth? • How long have dinosaurs been extinct? How long have humans existed? Did they coexist? • Does the climate of an area change over time, or has it always been the same? • Over geologic time, are organisms getting more or less complex?

  44. Bibliography • http://wrgis.wr.usgs.gov/docs/parks/gtime/ • http://www.cr.nps.gov/museum/exhibits/dino/geotime/geotime2.html • http://denali.gsfc.nasa.gov/sci_hi/sci_hi_2004_05/2004_05b.html • http://maritime.haifa.ac.il/departm/lessons/ocean/lect03.htm • http://www2.worldbook.com/wc/popup?path=features/dinosaurs&page=html/trilobite.htm&direct=yes • http://www.intelligentdesign.org/menu/evolution/fossils/fishes.htm • http://www2.worldbook.com/wc/popup?path=features/dinosaurs&page=html/mesozoic.htm&direct=yes • http://skullduggery.com/extinct.htm • http://www.lpi.usra.edu/education/timeline/gallery/images/063.jpg • http://library.thinkquest.org/11922/extinct/mammoth.htm • http://www.hmag.gla.ac.uk/Neil/Amber/ant.jpg • http://www.paleozoic.org/shows/tucson-2003/images/fs/petrified-stumps.jpg • http://www.gpc.edu/~pgore/myphotos/fossils/cast&mold.jpg • http://www.baystatereplicas.com/images/dino_multi_tracks2.jpg • http://www.humboldt.edu/~natmus/Case_indexes/Case_jpgs/MakeFossil.web/368.jpg • http://www.longpaddock.qld.gov.au/ClimateChanges/gifs/dnrPI2.gif

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