Earth's History

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Across
  1. 4. gap in the rock record caused by erosion or weathering
  2. 8. science of using tree rings
  3. 11. excellent index fossils for the Mesozoic era
  4. 13. sedimentary rock overlies another layer of sedimentary rock that has been eroded
  5. 14. contain a record of time within tree trunks
  6. 15. type of fossils that are easily recognized and useful for relative-age dating
  7. 16. state that an intrusion is younger than the rock it cuts across
  8. 17. bands of alternating light and dark colored sediments of sand, clay and silt
Down
  1. 1. principle that a rock layer must be older than the rock layer that contains them
  2. 2. principle that the oldest rocks are at the bottom and each consecutive layer is younger than the layer beneath it
  3. 3. a rock or sediment layer used as a marker
  4. 5. matching of rock in one geographic region to similar rocks in another region
  5. 6. unconformity of horizontal sedimentary rock on top of tilted eroded layers
  6. 7. excellent index fossils for the Paleozoic era
  7. 9. Zion National Park, Bryce Canyon, and the Grand Canyon are all part of ...
  8. 10. sedimentary rock overlies a layer of igneous or metamorphic rock
  9. 12. ______________ horizontality principle that sedimentary rocks are deposited in horizontal layers