8E2.1

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Across
  1. 4. system of chronological measurement that relate to the history of events in Earth's past, consisting of fossils and major events; This timeline includes the divisors of the 4.6 billion years of Earth's geologic and biologic existence, and divides time into eons, eras, periods, and epochs. The divisions of the time scale are based on major events that have caused major geologic or biologic change throughout history, such as mass extinctions.
  2. 7. or calculating the actual age
  3. 10. radioactive heavy metal that is an abundant source of nuclear energy that has 14 known isotopes used in radioactive dating
  4. 11. type of fossil that forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber.
  5. 12. the preserved remains or traces of an organism that lived in the past
  6. 13. the measurement of the known rates of decay of radioactive materials that an object contains in order to determine the age of the object
  7. 15. the fossil known to have lived in a particular geologic age that can be used to determine the date of the rock layer in which it was found
Down
  1. 1. type of fossil that forms when minerals soak into the buried remains, replacing the remains, and changing them into rock.
  2. 2. the complete elimination (dying out) of a species due to the species inability to survive and therefore adapt to its environment.
  3. 3. determining the age or order of things from the past or past events without
  4. 5. states that in undisturbed rock layers that newer layer will be deposited over older layers geology the study of the rocks, processes, and history of Earth
  5. 6. forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism
  6. 8. type of fossil that forms when the mud or sand hardens into stone where a footprint, trail, or burrow of an organism was left behind.
  7. 9. type of 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. 14. forms when a mold is filled with sand or mud that hardens into the shape of the organism