vocabulary Definitions Science 8

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Across
  1. 2. life The time required for half of a sample of a radioactive isotope to break down by radioactive decay to form a daughter isotope
  2. 7. time scale The standard method used to divide earths long natural history into manageable parts
  3. 8. A principal the geologic processes that occurred in the past can be explained by current geologic processes
  4. 9. The scientific study of the origin, history and structure of Earth and the processes that shape Earth
  5. 10. dating A method of determining the absolute age of an object by comparing the relative percentages of a radioactive isotope and a stable isotope
  6. 12. A principal that states that younger rocks lie above older rocks if the layers have not been disturbed
  7. 13. A break in the geologic record created when rock layers are eroded or when sediment is not deposited for a long period of time
Down
  1. 1. The weather conditions in an area over a long period of time
  2. 3. dating Any method of determining weather an event or object is older or younger than other event or objects
  3. 4. The trace or remains of an organism that lived long ago
  4. 5. core A long cylinder of ice obtained from drilling through ice caps or ice sheets
  5. 6. dating Any method of measuring the age of event or object in years
  6. 9. column An ordered arrangement or rock layers that is based on relative aged of the rocks and in which the oldest rocks are at the bottom
  7. 10. decay The process in which a radioactive isotspe tends to break down into a stable isotope of the smae element or another element
  8. 11. fossils A fossilized structure such as a footprint or a coprolite, that formed in sedimentary rock by animal activity on or within soft sediment