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Understanding Earth's Age: Fossils, Relative and Absolute Time in Geologic History

Dive into the fascinating world of geologic history and paleontology, exploring how we determine the age of the Earth. Learn about fossil formation, the types of fossils, and the principles of relative and absolute time. Understand the significance of fossils in reconstructing prehistoric life and the methods scientists use, including radiometric dating. This educational resource demystifies complex concepts and provides insight into Earth's timeline, making it easier to grasp the intricate relationships between geological processes and the history of life on our planet.

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Understanding Earth's Age: Fossils, Relative and Absolute Time in Geologic History

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Presentation Transcript

  1. RAP 3/14 pg. 42 How old is the Earth? How do we know?

  2. TOPIC: Geologic History 29.1 Fossils 29.2 Relative Time 29.3 Absolute Time

  3. Paleontology • The study of life that existed in prehistoric times

  4. I. Fossils -Preserved remains or traces of once living organisms

  5. A. Types 1. Original Remains -preserved in its entirety Ex: Wooly mammoths in ice and soil Insect in amber

  6. 2. Replaced remains -Soft parts replaced by minerals Ex: Petrified wood

  7. 3. Molds and Casts -Mold: hollow depression (cupcake pan) -Cast: copy of original fossil (cupcake)

  8. 4. Trace -indirect evidence of life Ex: trails footprints burrows bite marks

  9. Trace fossils And one more example... coprolite

  10. -thin carbon film 5. Carbonaceous Remains Ex. Fern print

  11. What do we know about this animal?

  12. Fossil Formation Fossil formed? Type Why/Why not? 1 No not deep enough 2 Yes Original Remains frozen 3 No too deep 4 No too much pressure 5 Yes replaced remains fused with minerals 6 Yes mould cast minerals filled in 7 Yes trace uplifted

  13. Fossil Formation • Burying Bodies • Making Fossils

  14. Who dung it?

  15. RAP 3/15 pg. 42 • What type of rock do most fossils occur in? • What is one method of preserving a fossil? B A 3. In the picture, which letter represents the mold? Which letter represents the cast?

  16. II. Relative Time- placing events in the sequence in which they occurred **Does not identify actual ** dates

  17. A. Principle of Uniform Processes 1. processes that occurred in past produce same results as today

  18. B. Principle of Superposition • Deposited sediments are compressed into layers, or strata 1. Oldest layer at ; youngest at bottom top

  19. Deciphering relative time is like detective work...

  20. Who Dunnit?! Someone took the last cookie in the cookie jar last night. The last person to leave is the culprit! Clues: • The Butler walks to work • The Handyman rides a bike • The Cook rides a motorcycle • The Maid drives a car • The Nephew has a seeing-eye dog

  21. Sequences on pg. 44 3 2 1

  22. 4 1 2 3

  23. C. Principle of Cross-Cutting Relationships 1. intrusion is always than rock it intrudes Igneous younger

  24. 4 2 1 3 5

  25. Gaps in Relative Time D. Unconformity 1. indicates where layers of rock are missing a. Exist because -Lack of deposition -Erosion Example

  26. E. Index Fossils 1. Four characteristics a. Easily recognizable b. Abundant c. Widespread in occurrence d. Existed only for a brief period

  27. When did I live?

  28. Who’s On First?: Period 6 Groups Lab Table 4 Mitchell Devin Jordan C. Kaitlin Bennett Lab Table 5 Davon Ashtyn Trey Lab Table 6 Josue Yony Ben Luke With Ms. Renwick Group 7 Chrissy Kaitlyn Bishop Dylan Wimer Anandhu Group 8 Zach Robert Jordan B. Lab Table 1 Shannon Jake Jenny Lab Table 2 Chase Brice Lab Table 3 Alex Daniel Dylan S.

  29. Put it all together... • Decoding geologic history... • And…

  30. B RAP 3/19 pg. 42 C A 2. Put the following events in the correct order. 1. Select the fossil you think would be the best index fossil and explain why. D

  31. F. Correlation 1. Matching of rock layers from one area to another

  32. Practice! unconformity Section 1 Section 2

  33. What is the sequence of rock layer from oldest to youngest? An unconformity (buried erosional surface) is represented by the interface between which two layers? Of layers E and F, which is oldest? Which layers are the same?

  34. III. Absolute Time A. Use ACTUAL dates to order events

  35. B. Methods 1. Tree rings 2. Varves- layer of sediment representing summer and winter

  36. RAP 3/20 pg. 46 • What is the difference between relative and absolute time? • What type of fossil shows evidence of an organism but not the organism itself?

  37. RAP 3/21 pg. 46**QUIZ ON FOSSILS, Relative and Absolute Time • What is the relative age of layer C and D? • What two things can cause an unconformity? • Which letter to the right represents an unconformity?

  38. 3. Radiometric dating Pb Compares ratio of naturally occurring unstable isotope (parent) and its decay products (daughter) Ur

  39. Parent = original element • Daughter = the product of the decay • Example: uranium-238 decays to lead-206

  40. i. Half-life -Time it takes for half the radioactive atoms to decay =1 half-life =2 half-lives

  41. In each half-life, the amount of atoms gets cut in half. =parent =daughter

  42. One half-life. =parent =daughter

  43. Two half-lives. =parent =daughter

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