Earth History

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Across
  1. 3. Two pieces of land change their vertical position compared to one another.
  2. 5. fossils of widely distributed organisms that lived during only one short period
  3. 7. A plate boundary where two plates move past each other in opposite directions
  4. 9. A break in the earth's crust
  5. 14. a fossil of a footprint, trail, burrow, or other trace of an animal rather than of the animal itself.
  6. 16. The age of a rock or fossil compared to the ages of other rock layers or fossils.
  7. 17. the numeric age of an object or event, often stated in years before the present, as established by an absolute-dating process, such as radiometric dating
  8. 19. event in which many types of living things become extinct at the same time
  9. 21. A record of the geologic events and life forms in Earth's history.
  10. 24. where magma cut through other rock layers underground
  11. 27. the gradual movement of the continents across the earth's surface through geological time.
  12. 28. Era middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants
  13. 29. breaks down eras, distinguished by the type of rock layers laid down during that time.
  14. 31. a broad span of geological time based on the general type of life existing during that time
  15. 32. fossil that forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber.
  16. 34. a drill core of ice that can help tell the climates of the past
  17. 35. how earth/land has changed over time
  18. 36. Era that began about 66 million years ago, known as the "Age of Mammals"
Down
  1. 1. Era that covers from 4.6 billion to 544 million years ago. During this time life developed as bacteria and softbodied, multicelled organisms.
  2. 2. length of time required for half of the radioactive atoms in a sample to decay
  3. 4. A plate boundary where two plates move toward each other.
  4. 6. A stable atom that results from the decay of a radioactive atom.
  5. 8. a fossil in which minerals replace all or part of an organism
  6. 10. (radioactive) Unstable form of the isotope
  7. 11. fossil that forms when organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock.
  8. 12. fossil that forms when a mold is filled with sand or mud that hardens into the shape of the organism
  9. 13. A term that typically describes a species that no longer has any known living individuals.
  10. 15. a rock that forms from compressed or cemented layers of sediment
  11. 18. Sections of the Earth's crust that move due to convection currents.
  12. 20. The breaking down of rocks and other materials on the Earth's surface.
  13. 22. fossil that forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism.
  14. 23. A plate boundary where two plates move away from each other.
  15. 25. A technique used to determine the actual age of a fossil on the basis of the amount of a radioactive element it contains
  16. 26. two pieces of land move horizontally past each other.
  17. 30. the largest division of geologic time
  18. 32. the part of geologic time 570-245 million years ago ; invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant.
  19. 33. breaks down periods, shortest span of time on the geological time scale.