Geologic+Cross+Sections+Simple

__Geologic Cross-Sections__ (Part 2) Draw the cross-sections 1. Tell which picture shows errosion between layers A &B and explain why. This is an unconformity. Find the intrusion and fault above. 2. Tell which happened first and why. || Find the unconformity between A and B. Also find the fault and intrusion. 3. Tell which of the three happened first and why. (oldest) 4. Tell which of the three happened second and why. 5. Tell which happened last and why. (youngest) ||
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D__etermining Relative Age__ (Textbook pages 274 & 275) (Part 1)
1. Explain what an intrusion is. 2. Explain how an intrusion forms, 3. Tell how an intrusion's age relates to the age of the rocks it passes through. 4. Explain what a fault is. 5. Explain how a fault forms. 6. Tell how the age of a fault relates to the rock it cuts through. 7. Explain cross-cutting relationships. 8. Explain how an unconformity forms. 9. Explain why there are gaps in the geologic record. Draw the following geologic cross-sections.

__Index Fossils__ (Textbook pages 276 & 277) (Part 3) 1. Explain how index fossils help geologist match rock layer to determine if they are the same age. 2. Why does an index fossil need to be widely distributed and must have only existed for a brief period of time. 3. Tell why ammonite fossils make good index fossils. 4. Quickly sketch an outline of the second index fossil in figure 8 that is not an ammonite. __Clues to Rock Layers__ (Textbook page 278) (Part 4) Sketch “Site 1” and “Site 2” Do items 1 through 8 on textbook page 278 1. What "fossil clues" in layers A and B indicate the kind of environment that existed when these rocks were formed? How did the environment change? 2. Which layer is the oldest? How do you know? 3. Whch of the layers fromed most recently? How do you know? 4. Why are there no fossils in layers C and E? 5. What kind of fossils are found in layer F? 6. Which layer at Site 1 might have formed at the same time as layer W as site 2? 7. What clues show an unconformity or gap in the horizontal rock layers? Which rock layers are missing? What might have happened to these rock layers? 8. Whch is older, intrusion V or layer Y? How do you know?