Unit 4 Science

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Across
  1. 2. a principal that states that younger rocks lie above older rocks if the layers have not been disturbed.
  2. 5. decay the process in which a radioactive isotope tends to break down into a stable element or another element.
  3. 6. the time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope.
  4. 8. the weather conditions in an area over a long period of time
  5. 9. Core a long cylinder of ice obtained from drilling through ice caps or ice sheets; used to study past climates
  6. 11. the scientific study of the origin, history, and structure of the earth and the processes that shape earth
  7. 13. dating any method of determining whether an event or object is older or younger than other events objects
  8. 14. the trace or remains of an organism that lived long ago, most commonly preserved in sedimentary rock
  9. 15. Fossil a fossilized structure, such as a footprint or a coprolite, that formed in sedimentary rock by an animal on or within soft sediment.
Down
  1. 1. a break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time.
  2. 3. a principal that geologic processes that occurred in the past can be explained by current geologic processes
  3. 4. Dating a method of determining the absolute age of an object by compare the relative percentages of a radioactive parent isotope and a stable daughter isotope.
  4. 7. Dating any method of measuring the age of an event or object in years.
  5. 10. column an ordered arrangement of rock layers that is based on the relative ages of the rocks and in which the oldest rocks are at the bottom
  6. 12. Time-Scale the standard method used to divide earth's long natural history into manageable parts