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Fossils

Fossils. Fossil are the preserved remains or traces of living things. They form when living things die and are buried by sediment. They are usually found in _______________ rock. 3 Main Types of Fossils. 1. Petrified fossils: formed by replacement.

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Fossils

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  1. Fossils

  2. Fossil are the preserved remains or traces of living things. • They form when living things die and are buried by sediment. • They are usually found in _______________ rock

  3. 3 Main Types of Fossils • 1. Petrified fossils: formed by replacement. • Water carrying minerals replace all or part of an organism. • 2. Molds and Casts: • Mold: hollow area in sediment in the shape of an organism • Cast: water carrying minerals seeps into the mold and deposits the minerals

  4. 3. Carbon films: As a buried plant or animal decays, it releases gases containing carbon. - the gases escape, leaving the carbon behind preserving the plant or animals image.

  5. Trace fossils: evidence that an organism was previously there • Example: footprints, trails, burrows

  6. Why do we study fossils? • 1. The fossil record provides evidence about the history of life on Earth. • The fossil record can tell us about past environments and climate change on Earth. • The fossil record can tell us about mass extinctions

  7. 2. The fossil record shows how organisms have changed over time. (evolution) • It shows how organisms have gone from simple to more complex organisms

  8. When rocks are rearranged by bending this is known as a : A. fault B. uplift C. fold D. I don’t know

  9. Identify the type of fault shown in the diagram. A. normal B. reverse C. strike-slip D. I don’t know

  10. Identify the force which caused the pictured fault. A. tension B. compression C. shear D. I don’t know

  11. Define the following: • Relative age • Absolute age • Law of superposition • Extrusions • Intrusions • Unconformity • Index fossil

  12. Age of Rocks • Relative age: the age a rock compared the age of surrounding rocks • Absolute age: the age of a rock since it was formed • Law of Superposition: in horizontal rock layers, the oldest is always on the bottom.

  13. - extrusions: lava that hardens on the surface • - always younger than the layer below it • - intrusions: magma that hardens below ground • - dike: always younger than the rock layer it cuts across • - unconformity: a gap in the geologic record • - missing layer(s) usually due to erosion

  14. -index fossil: a fossil that can be used to determine the relative age of rock layers • - fossil must be widely distributed and should • have existed for a short period of time. • Fossils record shows how life has become more complex. • Example : trilobites, ammonites

  15. The Law of Superposition states that: A. rock layers are deposited horizontally. B. rock layers on the bottom are the oldest. C. rock layers on the top are the oldest. D. I don’t know

  16. By studying fossils we can find out: A. when extinct organisms lived B. what extinct organisms behaved like C. the year they died D. I don’t know

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