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Subject
- United States. Congress. House13
- Geology, Stratigraphic10
- Election districts9
- Atlases8
- Stratigraphic correlation8
- Geology5
- Groundwater5
- Census districts4
- Coal4
- Gravity anomalies4
- Roads4
- Aquifers3
- Historical geography3
- Oil-shales3
- United States. Congress3
- Water table3
- Formations (Geology)2
- Human geography2
- Mines and mineral resources2
- Physical geography2