Human Dependence on Natural Resources

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Across
  1. 3. The layer of gas surrounding a planet that is held in place by gravity
  2. 5. Not replaceable by natural means within a short period of time
  3. 6. The sum of all living matter on Earth
  4. 7. Water that collects in cracks and pores in underground soil and rock layers
  5. 8. Resources that exist in the environment without human intervention
  6. 9. A source of supply of energy that can be used to generate electric power to meet people's needs
Down
  1. 1. Something that is needed by organisms and is not infinite in its abundance in the environment; if it is exhausted, then the organisms that need it cannot survive
  2. 2. Any natural process that happens to Earth's surface, such as weathering, erosion, or plate tectonics
  3. 4. Replaceable by natural means in a short period of time