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Geologic Time Vocabulary chapter 10- pg. 308

Learn about fossils, time periods, radioactive dating, and more in this geologic time lesson. Understand how scientists determine the Earth's history using the geologic timetable and rock record. Discover the importance of fossils in studying evolution and relative age. Dive into the different eras and divisions of the geologic time scale.

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Geologic Time Vocabulary chapter 10- pg. 308

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  1. Geologic Time Vocabulary chapter 10- pg. 308 • Absolute time/age • Archean • Cenozoic • Era • Epoch • Fossil • Geologic timetable/Scale • Half-life • Isotope • Index (guide) fossil • Relative time/age • Mesozoic • Paleozoic • Key bed • Uncomformity • Period • Radiometric Dating

  2. Bellringer WELCOME BACK! • Come get a note packet from the front desk! • You have 15 minutes to finish your geologic timeline – don’t forget drawings and coloring • When finished turn in by posters in back.

  3. Geo Time Objectives • Explain how fossils form • Identify the different types of fossils • Describe what fossils tell about organisms and environments of the past. • State the law of superposition • Describe how geologists determine the relative age of rocks • Explain how index fossils are useful to geologists • Explain what happens during radioactive decay • Describe what can be learned from radioactive dating • Explain why the Geo Time scale is used to show Earth’s History • Describe the different units of the Geologic Time Scale

  4. I. Geologic Time Table(6 min)

  5. A. Geologic Time Table 1. Summary of major events in Earth’s history preserved in the rock record 2. Fossils are an important part of this record 3. Rocks from different countries can be matched based on the fossil record

  6. B. Geologic Time Divisions • Based on major changes to plant or animal life -Longest segment of geologic time -Divisions within the Eras (differ in plant & animal life.) -Divisions within the Periods( shorter changes.) 1. Divisions a. Eras b. Periods c. Epochs

  7. Trilobite

  8. Triops and Sea Monkeys

  9. C. Major Eras 1. Archean Era 2. Proterozoic Era a. Earliest rocks formed in the Archean Era b. Little if any fossils a. Marked by rocks containing fossils of simple oceanic plants and worms b. No evidence of life on land Precambrian

  10. C. Major Eras 3. Paleozoic Era 4. Mesozoic Era a. Fossils contain both aquatic and non-aquatic plants and animals a. Dinosaurs present

  11. C. Major Eras 5.Cenozoic Era a. Began approximately 65 million years before present and continues Today b. Many mammals appear c. Ice age and man are relatively recent events

  12. D. 3 things to remember • 570 million years ago- life on land began • 250 million years ago- Dinosaurs form • 65 million years ago- extinction of dinosaurs & mammals form

  13. II. Telling Time Reading the Rock Record

  14. Understanding Time • Which scientist must understand time? • Geologist • Astronomers • Paleontologist • Meteorologists • Climatologists • Volcanologists • Oceanographers • Mineralogists • Petrologists: studies rocks in-depth.

  15. A. Time Determination Mount St. Helens May 18, 1980 a. Absolute Time 1.) Measured time. Radioactive dating made this possible 2.) Method of recording events that identifies the actual date the event occurred 3.) Difficult and expensive to determine for events before recorded time 1. 2 Time Types

  16. b. Relative Time 1.)Based primarily on fossils and the principle of superposition

  17. 1.) Why is it important? a. “The present is the key to the Past” b. If the time of two events are known, the interval between them can be calculated 2. Understanding Time

  18. B. Determining Relative Time 3 rules: a. Law of superposition 1.) In a sequence of undisturbed sedimentary rocks, the oldest rocks will be at the bottom b. Law of crosscutting relationships 1.) Igneous rocks are younger than the rocks they intrude into c. Law of included fragments 1.) Pieces of one rock found in another must be older than the rock they are found within

  19. What’s it really mean? Law of Superposition Law of Crosscutting Relationships

  20. What’s it really mean? Law of Included Fragments

  21. C. More Relative Time Information 1.Unconformity 2. Causes 3. Results Place in the rock record where layers of rock are missing Layers deposited and then removed Geologic Time Gap, no sediments were preserved.

  22. Unconformities Examples Unconformity Unconformity

  23. Let’s Sequence! • Turn your note packet over to the blank side. • Listen for further directions.

  24. Draw and Complete this Sequence

  25. Journal # 17 (4/1/13) Summary: Black Text. Pg. 599 #1-2 -Draw a pattern example for EACH of the three rules of rock sequencing in your comp. book.

  26. Geo Time Topic Questions

  27. Earth Science Bellringer • Get out your comp.book. Put it at the front of your desk so I can stamp Vocab and the Geo Time Bellringer. • Get out your notes and turn to the blank back page.

  28. 4. Order the rock layers from young to old. 5

  29. Final Round!

  30. HW: Due next class Create your own Geologic Rock Layers Include: • 12 layers total- colors & designs • Give each layer a letter (Not in order.) • One tilt, fault, or fold • Two unconformities • One Intrusion • One included fragment Put answers on the back.

  31. Everyday is a Holiday! Government Day!

  32. C. Use of Fossils • Shows changing life- evolution • Index/guide fossils- identify relative age of rock 1.) easy to recognize 2.) occur over a large area 3.) only existed for a short period, few rock layers • Key bed- rock layer used as an index fossil

  33. Geologic Time Bellringer: 1. Order the fossil’s from youngest to oldest. Hint: Some fossil may be the same age. (There should be 8 fossil levels.) True/False 2. Fossil’s are only found in one layer. 3. Older fossil’s are located in lower rock layers. 4. Fossil’s are found in metamorphic rock. 5. Fossil’s can be from plant or animals.

  34. Geologic Time Bellringer Answers: 1.) 1.Shark’s Tooth & Ichthyosaur 2. Ammonite 3. Pelecypod 4. Gastropod & Forminifers 5. Crinoid & Placoderm 6. Horn Coral 7. Eurypterid & Graptolite 8. Trilobite & Brachiopod True/False 2. Fossil’s are only found in one layer. 3. Older fossil’s are located in lower rock layers. 4. Fossil’s are found in metamorphic rock. 5. Fossil’s can be from plant or animals.

  35. III. Fossils & Measuring Absolute Time

  36. A. Fossil -any evidence of earlier life preserved in rock

  37. B. Types of Fossils • Original remains- actual, unchanged remains • Amber- remains in hardened sap

  38. 3. Mold- shape of material remains, filled in by new material called a cast. 4. Trace fossils- impression left by an animal & plants ex. Footprint, tracks, burrows

  39. C. Use of Fossils • Shows changing life- evolution • Index/guide fossils- identify relative age of rock 1.) easy to recognize 2.) occur over a large area 3.) only existed for a short period, few rock layers • Key bed- rock layer used as an index fossil

  40. D. How is absolute time determined? Mount St. Helens May 18, 1980 1.View the event

  41. 2. Radioactive decay • All materials contain radioactive elements a. These elements decay at a specific & constant rate, called a half-life.

  42. Uranium 238 Decay

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