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Semester Plan

Semester Plan. Geologic Time Meteorology Astronomy Oceanography. How do scientists know the age of the rocks? How has life changed over time?. Chapter 10 Clues to Earth’s Past. EQ: How do scientists know the age of the rocks? . Fossils .

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Semester Plan

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  1. Semester Plan • Geologic Time • Meteorology • Astronomy • Oceanography

  2. How do scientists know the age of the rocks? How has life changed over time?

  3. Chapter 10 Clues to Earth’s Past EQ: How do scientists know the age of the rocks?

  4. Fossils • Fossils= preserved remains or evidence of ancient living things • Uniformitarianism is a basis of understanding Earth’s past

  5. Scaphognathuscrassirostris • Pterosaur – flying reptile • Germany during the Late Jurassic. It had a wingspan of about one meter.  The German scientist, August Goldfuss, discovered these bones in 1826. 

  6. D3.7 Difficulty in defining the past • Fossils only form when buried under sediment (preferably, moist) before decomposition occurs • difficult for remains of animals living in arid/semi-arid habitats to fossilize • Only hard parts of individuals fossilize (bones) • animal bodies are usually eaten by detritivores, decomposed by bacteria, or broken down chemically • Individual phenotype? • Of remains fossilized, most remain buried in sediment/remain unfound

  7. To do • Read pages 329 – 333 • Take notes on ‘Formation of Fossils’ and ‘Types of preservation.’

  8. 10.2 Relative age dating EQ: How dos scientists know the age of rocks? TODAY: 1. Blog: How can YOU become a fossil?

  9. D3.7 Difficulty in defining the past • Fossils only form when buried under sediment (preferably, moist) before decomposition occurs • difficult for remains of animals living in arid/semi-arid habitats to fossilize • Only hard parts of individuals fossilize (bones) • animal bodies are usually eaten by detritivores, decomposed by bacteria, or broken down chemically • Individual phenotype? • Of remains fossilized, most remain buried in sediment/remain unfound

  10. Relative age • Age of rocks and geologic features compared with other rocks and features nearby

  11. 10.3 Absolute age dating EQ: How do scientists determine the age of rocks? Today: 1. Have your relative age dating packet ready. Coming around to check

  12. Relative vs. Absolute Age Dating Relative Absolute Determine absolute date of the rock • Determines ages of rocks in order that they were formed but without exact dates

  13. Radiometric dating • Isotopes= atoms of the same element that have the same number of protons but different number of neutrons

  14. Carbon-14 dating • Radioactive decay: Some isotopes are unstable, emit radiation and decay into “daughter” isotope • Carbon-14 is unstable isotope and decays into nitrogen-14 • Over time: • The amount of “parent” isotope, carbon-14, decreases • The amount of “daughter” isotope, nitrogen-14, increases • The ratio of the two indicates the age of the rock • Half life: time required for half of parent isotope to decay into daughter isotopes • E.g. Half life of carbon 14 is approx. 5730 years

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