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| 1 | Process in which oxygen chemically combines with another substance | 
 
 
| 2 | Natural process by which atmospheric and environmental agents disintegrate and decompose rocks | 
 
 
| 3 | Process of wearing away of the Earths surface by breaking down and carrying away soil, rock, or sediment | 
 
 
| 4 | Grinding and wearing away of rock surfaces through the mechanical action of other rock | 
 
 
| 5 | Remains of past plant and animal life | 
 
 
| 6 | Idea that geologic processes that occurred in the past can be explained by current geologic process | 
 
 
| 12 | Physical features on Earths surface | 
 
 
| 13 | Amount of time required for half an original sample of radioactive material to decay | 
 
 
| 15 | Atom of a substance that has the same number of protons but a different number of neutrons | 
 
 
| 16 | Movement of water through rock or soil | 
 
 
| 18 | Body of rock or sediment that allows the flow and stores groundwater | 
 
 
| 19 | Removal of substances that can be dissolved | 
 
 
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