Subject
- Gravity1
- Groundwater134
- Indian reservations1
- Inland water transportation1
- Joints (Geology)20
- Mineral industries4
- Mines and mineral resources3
- Moraines2
- Natural gas2
- Natural gas pipelines3
- Ohio State University1
- Oil fields2
- Petroleum2
- Petroleum pipelines3
- Petroleum refineries2
- Physical geography1
- Physiographic provinces1
- Public lands1
- Railroads7
- Reservoirs1