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Subject
- Geology83
- Geology, Structural18
- Geology, Stratigraphic14
- Submarine topography9
- Population density8
- Ethnic groups7
- Ocean bottom7
- Petroleum7
- Groundwater6
- Physical geography6
- Water table6
- Aquifers5
- Election districts5
- Land use5
- United States. Congress. House5
- Mines and mineral resources4
- River sediments4
- Ethnology3
- Gas fields3
- Gas wells3