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The Rock Record. Determining Relative Age. Mass Extinction. 65 million years ago ( mya ) – 50-85% of all species on Earth became extinct. In what geologic time period did this occur? (Page 8) What are some species that became extinct? Questions :
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The Rock Record Determining Relative Age
Mass Extinction • 65 million years ago (mya)– 50-85% of all species on Earth became extinct. • In what geologic time period did this occur? (Page 8) • What are some species that became extinct? • Questions: • How do we know that a mass extinction event occurred 65mya? • What caused the mass extinction? • Do you think it is important to understand what happened? Why?
Resulting in Extinction How do we know that organisms have become extinct?
Studying the Past • A thorough knowledge of the past is essential for understanding present and future processes. Iridium found in thin layers of rock. Iridium is found in high concentrations with in meteorites.
Studying Present Day Old Faithful, Yellowstone National Park
Studying Present Day Yellowstone = SUPER VOLCANO Past eruptions and the resulting ash deposits. Why is this important?
Evidence of Tsunami in Chile Why is this important?
Studying Present Day Tsunami, Japan 2011
Law of Superposition Rock Layer A Rock Layer B
Key Terms • Law of Crosscutting Relationships • Uniformitarianism • Relative Age • Law of Superposition • Principle of Original Horizontality • Unconformities • Nonconformity • Angular unconformity • Disconformity Define and provide diagrams for each.
Key Terms (H) • Inclusions • Index Fossils • Subsidence • Anticline • Syncline
Essential Questions • 1. Explain why its important for scientists to be able to determine the relative ages of rocks. • 2. State the Principle of Uniformitarianismin your own words. • 3. Explain how the Law of Superposition can be used to determine the relative age of sedimentary rocks. • 4. Explain the difference between an unconformity and a nonconformity.
Relative Age Which rock layer is oldest? Which is youngest? A B C What type of unconformity is found here? D E disconformity
Slide 1 Name the unconformity. Angular unconformity
Slide 3: Sequence the Events List the correct Order of events.