Changing Earth Vocab

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