Unit 2 Vocabulary Review

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Across
  1. 2. Continents move slowly across Earth's surface due to changes in the crust over time
  2. 7. Less dense crust forming Earth's continents, whose movement is used as evidence for plate tectonics
  3. 10. In an undisturbed sequence of sedimentary rocks, the oldest layers are at the bottom and the youngest are at the top
  4. 11. A German scientist who proposed the idea of continental drift
  5. 13. A timeline of Earth's history based on major events, such as mass extinctions, climate changes, and evolutionary milestones
  6. 17. A dating method used to determine the exact numerical age of a rock, fossil, or geologic event
  7. 18. A method of determining the age of rocks or fossils by measuring the amount of radioactive isotopes and their decay products
  8. 19. A boundary where two tectonic plates move away from each other
  9. 20. The principle that any geologic feature that cuts across another layer must be younger than the layer it cuts through
  10. 22. A dating method used to determine the order of geologic events or rock layers without identifying their exact age
Down
  1. 1. The process in which new oceanic crust forms at mid-ocean ridges and slowly moves outward, pushing older crust away from the ridge
  2. 3. An underwater mountain chain formed at divergent boundaries where new ocean crust is formed
  3. 4. The complete disappearance of a species when its last individual dies
  4. 5. The time it takes for half of the atoms in a radioactive isotope to decay into a new form
  5. 6. The natural process by which unstable atomic nuclei break down into more stable forms, releasing energy in the process
  6. 8. A boundary where to tectonic plates slide past one another horizontally
  7. 9. A boundary where two tectonic plates move toward each other
  8. 12. The slow circulatin of hot, less-dense rock rising and cooler, denser rock sinking in Earth's mantle
  9. 14. Dense crust beneath oceans that forms at mid-ocean ridges and moves through seafloor spreading
  10. 15. The preserved remains, traces, or impressions of ancient organisms, typically found in rock
  11. 16. A supercontinent that existed about 300 million years ago, when nearly all of Earth's landmasses were joined together
  12. 21. Earth's lithosphere is divided into large moving plates that interact at boundaries