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The Geologic Time Scale

The Geologic Time Scale. A Clock In the Rocks. Relative Dating. A technique used to determine the age of a fossil by comparing it to other fossils found in the layering of a rock Sedimentary rock = undisturbed Lower = oldest Upper = newest Vertical geologic section.

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The Geologic Time Scale

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  1. The Geologic Time Scale A Clock In the Rocks

  2. Relative Dating • A technique used to determine the age of a fossil by comparing it to other fossils found in the layering of a rock • Sedimentary rock = undisturbed • Lower = oldest • Upper = newest • Vertical geologic section. • Layer A is the oldest, layer C is the youngest. C B A

  3. Relative Dating (Cont) • Time of appearance and disappearance • Determines relative times of organisms

  4. Problems with Relative Dating • Gaps in record • Quality of Fossils

  5. Relative Dating vs. Absolute Dating

  6. Radioactive Dating • Absolute Dating • Rocks • Made of many elements • Radioactive • Elements that decay or break down at a steady and measurable rate - Used to age fossils and layers of Earth

  7. Radioactive dating • How is it measured? • Half-life- unit of measurement of decay • The amount of time required for half of the radioactive atoms to decay

  8. Radioactive Elements • Each element has a different half-life.

  9. Useful Dates once living material Drawback 60,000 years Carbon-14

  10. Earth Age? • All this data helped scientists come to the conclusion the earth is 4.5 billion years old

  11. Image Sources • http://3dparks.wr.usgs.gov/nyc/images/fig5.jpg • http://static.howstuffworks.com/gif/carbon-14.gif • http://qbx6.ltu.edu/s_schneider/courses/intro_astro/images/06-28.jpg • http://qbx6.ltu.edu/s_schneider/courses/intro_astro/images/06-28.jpg • http://www.uwlax.edu/MVAC/ProcessArch/ProcessArch/images/stylesW.jpg • http://upload.wikimedia.org/wikipedia/en/thumb/e/e8/Knightia.jpg/250px-Knightia.jpg • http://daneshnameh.roshd.ir/mavara/img/daneshnameh_up/4/4b/earth-age.jpg • http://evolution.berkeley.edu/evosite/lines/images/strat_column.gif

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