Earth’s Changing Systems

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Across
  1. 7. determining the age of rocks based on the decay of the elements
  2. 8. the variety of life in the world or in a particular habitat or ecosystem.
  3. 9. forces that change the surface of the earth from outside; i.e. humans, erosion, and weathering
Down
  1. 1. the process of new crust forming at a ridge and pushing older crust out
  2. 2. species that are not native to a specific location and have a tendency to spread to a degree believed to cause damage
  3. 3. forces that change the surface of the earth from within; i.e. divergent, convergent, and transform boundaries
  4. 4. number of species in an area
  5. 5. the length of time it takes for one-half of a radioactive element to change into another element
  6. 6. when all the species have died out